.NET, MVC, C#.NET, ASP.NET , Jquery, SQL, Kendo UI

ASP.NET MVC with Large JSONResult

2024-04-30T14:43:00.000-07:00

Error:- Error during serialization or deserialization using the JSON JavaScriptSerializer. The length of the string exceeds the value set on the maxJsonLength property.

Solution:-

In this help topic, we will use a custom JsonResult Class for ASP.Net MVC to avoid MaxJsonLength Exceeded Exception. The class is called LargeJsonResult.

Below is the implementation of the LargeJSONResult class:

using System;
using System.Web.Script.Serialization;
namespace System.Web.Mvc
{
    public class LargeJsonResult : JsonResult
    {
        const string JsonRequest_GetNotAllowed = "This request has been blocked because sensitive information could be disclosed to third party web sites when this is used in a GET request. To allow GET requests, set JsonRequestBehavior to AllowGet.";
        public LargeJsonResult()
        {
            MaxJsonLength = 1024000;
            RecursionLimit = 100;
        }
        public int MaxJsonLength { get; set; }
        public int RecursionLimit { get; set; }
        public override void ExecuteResult( ControllerContext context )
        {
            if( context == null )
            {
                throw new ArgumentNullException( "context" );
            }
            if( JsonRequestBehavior == JsonRequestBehavior.DenyGet &&
                String.Equals( context.HttpContext.Request.HttpMethod, "GET", StringComparison.OrdinalIgnoreCase ) )
            {
                throw new InvalidOperationException( JsonRequest_GetNotAllowed );
            }
            HttpResponseBase response = context.HttpContext.Response;
            if( !String.IsNullOrEmpty( ContentType ) )
            {
                response.ContentType = ContentType;
            }
            else
            {
                response.ContentType = "application/json";
            }
            if( ContentEncoding != null )
            {
                response.ContentEncoding = ContentEncoding;
            }
            if( Data != null )
            {
                JavaScriptSerializer serializer = new JavaScriptSerializer() { MaxJsonLength = MaxJsonLength, RecursionLimit = RecursionLimit };
                response.Write( serializer.Serialize( Data ) );
            }
        }
    }
}

In a Controller class called CustomersController, we will implement a method called GetCustomers which returns LargeJsonResult. If you are new to using the jqxGrid with ASP .NET MVC, you can take a look at this help topic: jquery-grid-to-sql-database.htm.

public LargeJsonResult GetCustomers()
{
    var dbResult = db.Customers.ToList();
    var customers = from customer in dbResult
                    select new
                    {
                        customer.CompanyName,
                        customer.ContactName,
                        customer.ContactTitle,
                        customer.Address,
                        customer.City
                    };
    return new LargeJsonResult { Data = customers, JsonRequestBehavior = System.Web.Mvc.JsonRequestBehavior.AllowGet };
}

The last step is to create and populate the jqxGrid with data.

var source = {
    datatype: "json",
    datafields: [{ name: 'CompanyName' }, { name: 'ContactName' },
    { name: 'ContactTitle' }, { name: 'Address' }, { name: 'City'} ],
    url: 'Customers/GetCustomers'
};
var dataAdapter = new $.jqx.dataAdapter(source);
$("#jqxgrid").jqxGrid({
    source: dataAdapter,
    theme: 'classic',
    columns: [{ text: 'Company Name', datafield: 'CompanyName', width: 250 },
                { text: 'Contact Name', datafield: 'ContactName', width: 150 },
                { text: 'Contact Title', datafield: 'ContactTitle', width: 180 },
                { text: 'Address', datafield: 'Address', width: 200 },
                { text: 'City', datafield: 'City', width: 120}]
});

Link - https://www.jqwidgets.com/jquery-widgets-documentation/documentation/asp.net-integration/asp.net-largejsonresult.htm

How to Scroll to an Element with Javascript

2024-04-28T10:51:00.000-07:00

Overview

Scrolling to a specific element or part of a webpage is mainly done to keep a user intact with the webpage for a longer period. A scroll is a function that can be used also to scroll to the beginning of a webpage from the bottom of the webpage instantly. Instant scrolling functionality is done or implemented using JavaScript. Scrolling to a particular section of a webpage adds a single-click functionality without much intervention from the user.

There are different JavaScript scroll to element methods that are used to implement the functionality of scrolling to a particular element. These methods include:

JavaScript scrollIntoView method.
JavaScript scroll method.
JavsScript scrollTo method. In this article, we will understand them thoroughly.

Introduction

Before learning about the JavaScript scroll to element, Let's learn a bit about JavaScript.

JavaScript is an object-oriented programming language used on web pages. JavaScript is the web programming language used on both the client and server sides to provide dynamic and interactive behavior in a webpage. It is a lightweight and easy-to-understand programming language. JavaScript is the most popular programming language in the world. It is a scripting language of a webpage that can be used even by non-browser environments like NodeJs, Adobe Acrobat, etc. Languages like HTML and CSS are used to provide structure and styling to a webpage respectively whereas JavaScript engages users by providing interactiveness to a webpage.

Now, let's learn about the Scroll function and the JavaScript scroll to element methods that implement the Scroll function.

Scrolling refers to functionality that moves the user from a specific part of the webpage to another. The scrolling in a website can be done by the physical components such as a scroll bar or with the help of buttons which are solely made to scroll in a specific element.

Scrolling to a specific element or part of a webpage is done using methods available in Javascript scroll to element which are as follows:

scrollIntoView() method
scrollTo() method
scroll() method

Now, we will discuss each of the above-mentioned methods used for scrolling with proper explanations and examples.

The ScrollIntoView Method

The scrollIntoView method in JavaScript is used to scroll to a specific element of a webpage in a web browser. Specifically, in the JavaScript scrollIntoView method, the scrolling is done based on the scrollable parent element. In general, most of the time the parent element will be the window of the web browser but in some of the scenarios, When the required scrollable element is placed within another scrollable element then the scrolling is done concerning the parent element rather than the window of the web browser's window. The scrollIntoView() method helps to carry out the scrolling of an element into the visible area of the browser window.

Now, let's see the syntax of scrollintoview method.

Syntax

element.scrollIntoView();

Parameter

There are several customizations available for the scrollIntoView() method which is done by passing scrollIntoViewOptions as the parameter.

scrollIntoView method takes a parameter which is known as the scrollIntoViewOptions. The scrollIntoViewOptions object contains the following customization properties:

Behaviour :- This property of scrollIntoViewOptions tells about the scrolling behavior. Whether the scrolling is done using scrollintoview method should contain an animation or there should be a normal instant scrolling without any animation up to the specific element. This property contains the following values which can be passed with the parameter:
- smooth: This value specifies smooth scrolling that is the scrolling with animation.
- auto: This value specifies instant scrolling to the required element without any animation.
Inline :- This property of scrollIntoViewOptions tells about the alignment mainly horizontal alignment of the required element concerning the parent scrollable element when using the scrollintoview method. This property contains the following values which can be passed with the parameter:
- start: This value specifies that the required element is aligned to the left or start of the parent scrollable element.
- center: This value specifies that the required element is aligned to the center of the parent scrollable element.
- end: This value provides that the required element is aligned at the end or right of the parent scrollable element.
- nearest: This value specifies that the element should be aligned according to the situation. If the element is at the right or the end then the required elements will also be aligned at the end. Similarly, if the element is at the left or the starting then the required elements will also be aligned at the left.
Block :- This property of scrollIntoViewOptions tells about the vertical alignment of a required element concerning the parent scrollable element when using the scrollintoview method. This property contains the following values which can be passed with the parameter:
- start: This value specifies that the required element is aligned at the top or start of the parent scrollable element.
- center: This value specifies that the required element is aligned to the center of the parent scrollable element.
- end: This value specifies that the required element is aligned at the bottom of the parent scrollable element.
- nearest: This value specifies that the element should be aligned according to the situation. If the element is at the top then the required elements will also be aligned at the top. Similarly, if the element is at the bottom then the required elements will also be aligned at the bottom.

Now, let's take an example to understand the scrollIntoView() method with proper implementation and explanation.

Code:

<!DOCTYPE html>
  <html lang="en">
  <head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Scroll Method in JS</title>
  </head>
  <style>
    #scroll {
      height: 450px;
      width: 350px;
      overflow: auto;
      background: rgb(243, 242, 245);
    }

    #content {
      margin: 500px;
      height: 800px;
      width: 2000px;
      background-color: rgb(250, 245, 243);
    }
  </style>

  <body>
    <h1>The scrollIntoView() Method</h1>
    <button onclick="scrollFunction()">Scroll</button>

    <p>Click on the "Scroll" button</p>

    <div id="scroll">
      <div id="content">
        <p>scrollIntoView() method is used.</p>
      </div>
    </div>

    <script>
      function scrollFunction() {
        const element = document.getElementById("content");
        element.scrollIntoView();
      }
    </script>
  </body>
</html>

Output:

Ref : https://www.scaler.com/topics/javacript-scroll-element/

Custom Web Browser in MVC

2024-04-22T10:43:00.000-07:00

we need to add webbrowser with threading other wise we will get ActiveX control '8856f961-340a-11d0-a96b-00c04fd705a2' cannot be instantiated because the current thread is not in a single-threaded apartment. error

this is the way we can make webbrowser work in asp.net webpages

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Threading;
using System.Windows.Forms;

/// <summary>
/// Summary description for CustomBrowser
/// </summary>
public class CustomBrowser
{
    public CustomBrowser()
    {
        //
        // TODO: Add constructor logic here
        //
    }

    protected string _url;
    string html = "";
    public string GetWebpage(string url)
    {
        _url = url;
        // WebBrowser is an ActiveX control that must be run in a
        // single-threaded apartment so create a thread to create the
        // control and generate the thumbnail
        Thread thread = new Thread(new ThreadStart(GetWebPageWorker));
        thread.SetApartmentState(ApartmentState.STA);
        thread.Start();
        thread.Join();
        string s = html;
        return s;
    }

    protected void GetWebPageWorker()
    {
        using (WebBrowser browser = new WebBrowser())
        {
            //  browser.ClientSize = new Size(_width, _height);
            browser.ScrollBarsEnabled = false;
            browser.ScriptErrorsSuppressed = true;
            browser.Navigate(_url);

            // Wait for control to load page
            while (browser.ReadyState != WebBrowserReadyState.Complete)
                Application.DoEvents();

            html = browser.DocumentText;

        }
    }

}

in webpage

CustomBrowser browser = new CustomBrowser();
string s = browser.GetWebpage("http://localhost:8781/WebSite3/Default3.aspx");
Response.Write(s);

Ref - https://stackoverflow.com/questions/10688281/webbrowser-class-in-asp-net-website

Start stop Service from Form App c#

2024-03-20T23:22:00.000-07:00

Add a reference to System.ServiceProcess.dll. Then you can use the ServiceController class.

// Check whether the Alerter service is started.
ServiceController sc  = new ServiceController();
sc.ServiceName = "Alerter";
Console.WriteLine("The Alerter service status is currently set to {0}", 
                   sc.Status.ToString());

if (sc.Status == ServiceControllerStatus.Stopped)
{
   // Start the service if the current status is stopped.
   Console.WriteLine("Starting the Alerter service...");
   try 
   {
      // Start the service, and wait until its status is "Running".
      sc.Start();
      sc.WaitForStatus(ServiceControllerStatus.Running);

      // Display the current service status.
      Console.WriteLine("The Alerter service status is now set to {0}.", 
                         sc.Status.ToString());
   }
   catch (InvalidOperationException)
   {
      Console.WriteLine("Could not start the Alerter service.");
   }
}

Ref: https://stackoverflow.com/questions/11062841/start-stop-service-from-form-app-c-sharp

SQL Server Login error: Login failed for user 'NT AUTHORITY\SYSTEM'

2024-03-18T23:00:00.000-07:00

Login failed for user 'NT AUTHORITY\SYSTEM'

I tried to add NT AUTHORITY/SYSTEM to SSMS (SQL Server Management Studio) logins, but it was already a principal, showing the following error:

Solution : https://stackoverflow.com/questions/24822076/sql-server-login-error-login-failed-for-user-nt-authority-system

Allow NT AUTHORITY/SYSTEM to server Role as sysadmin.

.NET: How to have background thread signal main thread data is available?

2024-01-18T09:47:00.000-08:00

Here's a code sample for the System.ComponentModel.BackgroundWorker class.

    private static BackgroundWorker worker = new BackgroundWorker();
    static void Main(string[] args)
    {
        worker.DoWork += worker_DoWork;
        worker.RunWorkerCompleted += worker_RunWorkerCompleted;
        worker.ProgressChanged += worker_ProgressChanged;
        worker.WorkerReportsProgress = true;

        Console.WriteLine("Starting application.");
        worker.RunWorkerAsync();

        Console.ReadKey();
    }

    static void worker_ProgressChanged(object sender, ProgressChangedEventArgs e)
    {
        Console.WriteLine("Progress.");
    }

    static void worker_DoWork(object sender, DoWorkEventArgs e)
    {
        Console.WriteLine("Starting doing some work now.");

        for (int i = 0; i < 5; i++)
        {
            Thread.Sleep(1000);
            worker.ReportProgress(i);
        }
    }

    static void worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
    {
        Console.WriteLine("Done now.");
    }

Ref - https://stackoverflow.com/questions/122882/net-how-to-have-background-thread-signal-main-thread-data-is-available

C# Generic class to parse value - "GenericConverter"

2023-11-24T06:38:00.000-08:00

public class GenericConverter

{

public static T Parse<T>(string sourceValue) where T : IConvertible

{

return (T)Convert.ChangeType(sourceValue, typeof(T));

}

public static T Parse<T>(string sourceValue, IFormatProvider provider) where T : IConvertible

{

return (T)Convert.ChangeType(sourceValue, typeof(T), provider);

}

public static class TConverter

{

public static T ChangeType<T>(object value)

{

return (T)ChangeType(typeof(T), value);

}

public static object ChangeType(Type t, object value)

{

TypeConverter tc = TypeDescriptor.GetConverter(t);

return tc.ConvertFrom(value);

}

public static void RegisterTypeConverter<T, TC>() where TC : TypeConverter

{

TypeDescriptor.AddAttributes(typeof(T), new TypeConverterAttribute(typeof(TC)));

}

----------------------------------------------

usage

DateTime x = GenericConverter.Parse<DateTime>("12.10.2007", providerTR); // ddMMyyyy

Console.WriteLine(x);

DateTime y = GenericConverter.Parse<DateTime>("12.10.2007", providerEN); // MMddyyyy

Console.WriteLine(y);

int iValue = GenericConverter.Parse<int>("12");

Console.WriteLine(iValue);

Console.WriteLine(TConverter.ChangeType<float>("00454545458"));

DateTime datetime = GenericConverter.Parse<DateTime>("12.10.2007");

How do I encode and decode a base64 string?

2023-05-23T04:04:00.000-07:00

Encode

public static string Base64Encode(string plainText) 
{
  var plainTextBytes = System.Text.Encoding.UTF8.GetBytes(plainText);
  return System.Convert.ToBase64String(plainTextBytes);
}

Decode

public static string Base64Decode(string base64EncodedData) 
{
  var base64EncodedBytes = System.Convert.FromBase64String(base64EncodedData);
  return System.Text.Encoding.UTF8.GetString(base64EncodedBytes);
}

Generic function to call Web API

2022-11-29T00:04:00.001-08:00

public class RestClient

{

public static async Task<T> CallServiceAsync<T>(string token, string endPoint, string url, object requestBodyObject, string method, string operation = null) where T : class

{

if (token == null)

throw new Exception("Please provide token");

// Initialize an HttpWebRequest for the current URL.

var webReq = (HttpWebRequest)WebRequest.Create(endPoint + url);

webReq.Method = method;

webReq.Accept = "application/json";

//Add basic authentication header if username is supplied

if (!string.IsNullOrEmpty(token))

webReq.Headers["Authorization"] = "Bearer " + token;

webReq.Headers["Content-Type"] = "application/json";

//Add key to header if operation is supplied

if (!string.IsNullOrEmpty(operation))

webReq.Headers["Operation"] = operation;

//Serialize request object as JSON and write to request body

if (requestBodyObject != null)

{

var requestBody = JsonConvert.SerializeObject(requestBodyObject);

webReq.ContentLength = requestBody.Length;

var streamWriter = new StreamWriter(webReq.GetRequestStream(), Encoding.ASCII);

streamWriter.Write(requestBody);

streamWriter.Close();

}

var response = await webReq.GetResponseAsync();

if (response == null)

{

return default;

}

var streamReader = new StreamReader(response.GetResponseStream());

var responseContent = streamReader.ReadToEnd().Trim();

var jsonObject = JsonConvert.DeserializeObject<T>(responseContent);

return jsonObject;

}

How to convert JavaScript Date without time stamp

2020-11-11T09:01:00.005-08:00

At some point when setting pika date min date I had to use JavaScript date variable without time stamp.

When you try JavaScript new Date() in browser console, you can see date with time stamp.

To remove time stamp what I did was use new Date with year , month and day parameters.

new Date(new Date().getFullYear(),new Date().getMonth() , new Date().getDate())

Open Multiple URL

2020-09-27T04:09:00.002-07:00

Insert website URLs in each lines and click on Open URLs button.

.Net C# match a UK postcode with a regular expression

2020-03-06T01:54:00.001-08:00

UK postcode Validation in C#

[RegularExpression(@"^(([a-zA-Z]{1,2}[0-9][A-Z0-9]?|ASCN|STHL|TDCU|BBND|[BFS]IQQ|PCRN|TKCA) ?[0-9][a-zA-Z]{2}|BFPO ?[0-9]{1,4}|(KY[0-9]|MSR|VG|AI)[ -]?[0-9]{4}|[a-zA-Z]{2} ?[0-9]{2}|GE ?CX|GIR ?0A{2}|SAN ?TA1)$", ErrorMessage = "Invalid Post Code.")]
public string PostCode { get; set; }

Refer - https://en.wikipedia.org/wiki/Postcodes_in_the_United_Kingdom

Setting attributes of a property in partial classes / Is it possible to add an attribute to a property in a partial class?

2020-02-20T02:03:00.002-08:00

Question

I have an employee class generated by the Entity Framework (EF).

public partial class employee
{
    private string name;
    public string Name
    {
        get{return name;}
        set{ name = value;}
    }
}

Now I want to put a required attribute in the name property to use in for MVC3 validation in another employee partial class which is written by me in order to extend the one which is generated by EF so that I don't have to rewrite my code if I refresh the model generated by EF.

My written partial class is in the same assembly and namespace.

public partial class employee
{
    // What should I write here to add required attribute in the Name property?
}

Answer

It is actually possible only through buddy class but it is not recommended way. You should keep your validation in the custom view model because often you need different validations for different views but your entity can keep only a single set of validation attributes.

Example of buddy class:

using System.ComponentModel.DataAnnotations;

[MetadataType(typeof(EmployeeMetadata))]
public partial class Employee
{
  private class EmployeeMetadata
  {
     [Required]
     public object Name; // Type doesn't matter, it is just a marker
  }
}

Ref : https://entityframework.net/knowledge-base/6813320/setting-attributes-of-a-property-in-partial-classes

Create and Configure a User in MSSQL

2019-12-17T21:24:00.003-08:00

This article will show you how to create and configure a user in MSSQL.

Open SQL Server Management Studio (SSMS).
Connect to SQL Server using your log in information.
In the left-hand panel, expand Security > Logins.
Right click Logins and select New Login from the drop-down menu.
Assign a Login name and select the authentication method and default database/language.
Note: Only Domains can use Windows Authentication.

If you are using SQL authentication you will need to enter an initial password and choose the enforcement options for password policy and expiration as well as whether or not the user will need to change their password when they log in.
In the left-hand panel, click Server Roles to assign any server roles you want this user to have, including bulkadmin, dbcreator, public, and so on.
In the left-hand panel, click Securables and then click Search.

The Add Objects dialog box displays, where you can choose specific objects, objects of a certain type or the server itself. Select one and click OK.
On the Securables page, select Grant, With Grant or Deny as necessary for any/all of the objects in the explicit box.

Grant will grant access to the securable, with grant will allow the user to grant access to the securable and deny will expressly deny permission to the securable no matter what roles or permissions the user may have.
In the left-hand panel, click Status to grant or deny permission to the Database Engine, enable or disable the login and to unlock the account should it get locked out.

When you have finished modifying the settings, click OK to create the user and exit the new login creation window.

Ref: https://support.rackspace.com/how-to/creating-and-configuring-a-user-in-mssql/

Typescript - Self-Executing Anonymous Functions

2019-11-29T04:37:00.004-08:00

/**
 * Self executing anonymous function using TS.
 */
(()=> {
    // Whatever is here will be executed as soon as the script is loaded.
    console.log('executed')
})();

I want a built a plugin that may work for Node.js, also for fron-tend as well.

In that case you should compile your TypeScript in AMD and use an AMD loader on the frontend, like http://requirejs.org/docs/start.html

On the server side, you would need to use requirejs node package as well to load the file. Take a look at this: http://requirejs.org/docs/node.html

Basically there are two ways to compile TS to JS, using AMD, which is browser compliant, or using CommonJS, which is node.js compliant. Loading an AMD script in the browser or in the server needs to use an AMD compliant loader, and *requirejs** is one of them. (the most famous/used I'd say)

Ref : https://stackoverflow.com/questions/30274464/typescript-self-executing-anonymous-functions

TempData keep() vs peek()

2019-07-03T00:46:00.001-07:00

When an object in a TempDataDictionary is read, it will be marked for deletion at the end of that request.

That means if you put something on TempData like

TempData["value"] = "someValueForNextRequest";

And on another request you access it, the value will be there but as soon as you read it, the value will be marked for deletion:

//second request, read value and is marked for deletion
object value = TempData["value"];

//third request, value is not there as it was deleted at the end of the second request
TempData["value"] == null

The Peek and Keep methods allow you to read the value without marking it for deletion. Say we get back to the first request where the value was saved to TempData.

With Peek you get the value without marking it for deletion with a single call, see msdn:

//second request, PEEK value so it is not deleted at the end of the request
object value = TempData.Peek("value");

//third request, read value and mark it for deletion
object value = TempData["value"];

With Keep you specify a key that was marked for deletion that you want to keep. Retrieving the object and later on saving it from deletion are 2 different calls. See msdn

//second request, get value marking it from deletion
object value = TempData["value"];
//later on decide to keep it
TempData.Keep("value");

//third request, read value and mark it for deletion
object value = TempData["value"];

You can use Peek when you always want to retain the value for another request. Use Keep when retaining the value depends on additional logic.

You have 2 good questions about how TempData works here and here

Ref : https://stackoverflow.com/questions/21252888/tempdata-keep-vs-peek

Adding Ctrl-Click “Go To Definition” support to Visual Studio 2015

2019-06-04T23:41:00.002-07:00

So here's how I fixed this.

First download Noah Richard's extension from: https://visualstudiogallery.msdn.microsoft.com/4b286b9c-4dd5-416b-b143-e31d36dc622b
Save the .vsix file somewhere on your computer
Open the file with Winzip / Winrar or similar (it's just a disguised .zip file so you could change the extension to .zip)
Open the extension.vsixmanifest file in a text editor
Add the following lines inside the <SupportedProducts>...</SupportedProducts> section:

<VisualStudio Version="14.0">
   <Edition>Pro</Edition>
</VisualStudio>

Update the zip file with the modified file and change it back to a .vsix file.
Double click the .vsix and install.

Ref : https://stackoverflow.com/questions/33301909/adding-ctrl-click-go-to-definition-support-to-visual-studio-2015

Visit - https://marketplace.visualstudio.com/items?itemName=NoahRichards.GoToDefinition
https://marketplace.visualstudio.com/items?itemName=VisualStudioPlatformTeam.ProductivityPowerTools2015

How to increase timeout for your ASP.NET Application ?

2019-05-23T04:42:00.001-07:00

A. executionTimeout attribute of httpRuntime element (web.config):

ASP.NET will timeout the request, if it is not completed within “executionTimeout” duration value. And System.Web.HttpException: Request timed out exception will be thrown by ASP.NET Application.
executionTimeout attribute of httpRuntime element (in the web.config) can be used to change the request timeout duration for ASP.NET Application. executionTimeout value is specified in seconds. Default value is 110 seconds.

<configuration>
<system.web>
<httpRuntime targetFramework="4.5.1" executionTimeout="500" />
</system.web>
</configuration>

B. timeout attribute of sessionState element (web.config):

If the user remains idle for duration specified in timeout attribute vaule of sessionState element (in web.config), then his session will expire.

timeout attribute of sessionState element (in the web.config) can be used to change session timeout duration for ASP.NET Application. timeout value is specified in minutes. Default value is 20 minutes.

<configuration>
<system.web>
<sessionState timeout="20"></sessionState>
</system.web>
</configuration>

C. Idle Time-out Settings for an Application Pool (IIS):

If the worker process remain idle for duration specified in Idle Time-out Settings for an Application Pool , then worker process will shut down.
Idle Time-out Settings for an Application Pool value is specified in minutes. The default value for Idle Time-out Settings for an Application Pool is 20 minutes.

D. SqlCommand.CommandTimeout (SQL SERVER):

ADO.NET will wait for duration specified in SqlCommand.CommandTimeout before cancelling the query.

using (var connection = new SqlConnection(connectionString))
{
connection.Open();
SqlCommand command = new SqlCommand(queryString, connection);
// Setting command timeout to 100 second
command.CommandTimeout = 100;
command.ExecuteNonQuery();
}

SqlCommand.CommandTimeout value is specified in seconds. The default value of SqlCommand.CommandTimeout is 30 seconds.

E. SqlConnection.ConnectionTimeout:

If connection is not opened within the duration specified in SqlConnection.ConnectionTimeout, timeout exception will be thrown.

Data Source=(local);Initial Catalog=TechCartNow;Integrated Security=SSPI;Connection Timeout=30

SqlConnection.ConnectionTimeout value is specified in seconds. The default value of SqlCommand.CommandTimeout is 15 seconds.

Ref: https://www.techcartnow.com/increase-timeout-asp-net-application/

Override AccessTokenExpireTimeSpan - Session Expire too early

2019-04-08T09:11:00.004-07:00

You have to set the expiration time in the TokenEndPoint method instead of GrantResourceOwnerCredentials method:

public override Task TokenEndpoint(OAuthTokenEndpointContext context)
{
    ...

    if (condition)
    {
        context.Properties.ExpiresUtc = DateTime.UtcNow.AddDays(14);
    }

    ...
}

Ref: https://stackoverflow.com/questions/32120754/override-accesstokenexpiretimespan

SQL Server replace, remove all after certain character

2019-04-08T02:47:00.002-07:00

Use LEFT combined with CHARINDEX:

UPDATE MyTable
SET MyText = LEFT(MyText, CHARINDEX(';', MyText) - 1)
WHERE CHARINDEX(';', MyText) > 0

Note that the WHERE clause skips updating rows in which there is no semicolon.

Here is some code to verify the SQL above works:

declare @MyTable table ([id] int primary key clustered, MyText varchar(100))
insert into @MyTable ([id], MyText)
select 1, 'some text; some more text'
union all select 2, 'text again; even more text'
union all select 3, 'text without a semicolon'
union all select 4, null -- test NULLs
union all select 5, '' -- test empty string
union all select 6, 'test 3 semicolons; second part; third part;'
union all select 7, ';' -- test semicolon by itself    

UPDATE @MyTable
SET MyText = LEFT(MyText, CHARINDEX(';', MyText) - 1)
WHERE CHARINDEX(';', MyText) > 0

select * from @MyTable

I get the following results:

id MyText
-- -------------------------
1  some text
2  text again
3  text without a semicolon
4  NULL
5        (empty string)
6  test 3 semicolons
7        (empty string)

Ref: https://stackoverflow.com/questions/1668014/sql-server-replace-remove-all-after-certain-character

How to set up git server on local network (Windows tutorial)

2019-03-14T10:45:00.003-07:00

It is just easy as 1, 2, 3:
1) Go to folder, where you want to initialize server. Give it a name without spaces (or you will need to use quotes everywhere later to access this folder!)

2) Open git bash in this folder

3) Type

git init yourpreferredname.git --bare

(Note: you can try to name your folder without ‘.git’ at the end but in some cases it led to troubles later)

Congrats! You’ve just set up your server! Let’s find out how to connect to it

4) Choose where you want to initialize client repository and open git bash there. Type:

git clone <path_to_your_server>

IMPORTANT! DO NOT FORGET TO CHANGE BACKSLASH (‘\’) IN THE PATH TO DIRECT SLASH(‘/’)

Congrats! You can use this repository as usual and open it with your favorite git client.
Ok, but how to connect to this server from another computer in local network? Easy!

5) Firstly go to Control Panel > Network And Sharing Center > Change advanced sharing settings
Tick turn on network discovery:

Then go to folder where you have set up server and share it with users that you want to give permission for accessing it.

6) Send network path to clients. For them nothing changes: they do the same thing to connect to server:

(Tip: Do not forget about slashes)

That’s all! If you have any troubles with accessing the server from other computers — try to play with security settings for sharing folders.

Ref : https://medium.com/@piteryo7/how-to-set-up-git-server-on-local-network-windows-tutorial-7ec5cd2df3b1

Zipping up files from a MemoryStream

2019-03-04T08:17:00.000-08:00

Recently I needed to write some .NET code that zipped up some files and downloaded the zip without touching the file system. I struggled to find a good example, so I thought I’d post the code here …

Assuming that we’ve got the source files in memory in the following structure:

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public class SourceFile

{

    public string Name { get; set; }

    public string Extension { get; set; }

    public Byte[] FileBytes { get; set; }

}

We can use the following code to zip these files up and send the zip in the response:

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public ActionResult Index()

{

    // get the source files

    List<SourceFile> sourceFiles = new List<SourceFile>();

    // ...

    // the output bytes of the zip

    byte[] fileBytes = null;

    // create a working memory stream

    using (System.IO.MemoryStream memoryStream = new System.IO.MemoryStream())

    {

        // create a zip

        using (System.IO.Compression.ZipArchive zip = new System.IO.Compression.ZipArchive(memoryStream, System.IO.Compression.ZipArchiveMode.Create, true))

        {

            // interate through the source files

            foreach (SourceFile f in sourceFiles)

            {

                // add the item name to the zip

                System.IO.Compression.ZipArchiveEntry zipItem = zip.CreateEntry(f.Name + "." + f.Extension);

                // add the item bytes to the zip entry by opening the original file and copying the bytes 

                using (System.IO.MemoryStream originalFileMemoryStream = new System.IO.MemoryStream(f.FileBytes))

                {

                    using (System.IO.Stream entryStream = zipItem.Open())

                    {

                        originalFileMemoryStream.CopyTo(entryStream);

                    }

                }

            }

        }

        fileBytes = memoryStream.ToArray();

    }

    // download the constructed zip

    Response.AddHeader("Content-Disposition", "attachment; filename=download.zip");

    return File(fileBytes, "application/zip");

}

Ref : https://www.carlrippon.com/zipping-up-files-from-a-memorystream/

Date and Time Formatting in JavaScript like .NET C# or VB.NET

2019-02-20T09:39:00.001-08:00

Custom Date and Time formatting in JavaScript like in .NET C# or VB.NET

Introduction

A date and time format string defines the text representation of a Date() object, that results in a custom format string. Any string that is not a standard date and time format string is interpreted as a custom date and time format string.

You can download the format.date JavaScript Utility, an application that enables you to apply format strings to date and time values and displays the result in string format.

Background

In formatting operations, custom date and time format strings can be used with the format method of a Date() instance.

The format method requires that an input string conforms exactly to a particular pattern for the parse operation to succeed, otherwise it will give you an error (e.g. ERROR: Not supported method [method name]).

The following table describes the custom date and time format and displays a result string produced by each format.

Format	Description	Date Example	Output
"d"	The day of the month, from 1 through 31.	5/1/2014 1:45:30 PM	1
"dd"	The day of the month, from 01 through 31.	5/1/2014 1:45:30 PM	01
"ddd"	The abbreviated name of the day of the week.	5/15/2014 1:45:30 PM	Thu
"dddd"	The full name of the day of the week.	5/15/2014 1:45:30 PM	Thursday
"f"	The tenths of a second in a date and time value.	5/15/2014 13:45:30.617	6
"ff"	The hundredths of a second in a date and time value	5/15/2014 13:45:30.617	61
"fff"	The milliseconds in a date and time value.	5/15/2014 13:45:30.617	617
"F"	If non-zero, the tenths of a second in a date and time value.	5/15/2014 13:45:30.617	6
"FF"	If non-zero, the hundredths of a second in a date and time value.	5/15/2014 13:45:30.617	61
"FFF"	If non-zero, the milliseconds in a date and time value.	5/15/2014 13:45:30.617	617
"h"	The hour, using a 12-hour clock from 1 to 12.	5/15/2014 1:45:30 AM	1
"hh"	The hour, using a 12-hour clock from 01 to 12.	5/15/2014 1:45:30 AM	01
"H"	The hour, using a 24-hour clock from 0 to 23.	5/15/2014 1:45:30 AM	1
"HH"	The hour, using a 24-hour clock from 00 to 23.	5/15/2014 1:45:30 AM	01
"m"	The minute, from 0 through 59.	5/15/2014 1:09:30 AM	9
"mm"	The minute, from 00 through 59.	5/15/2014 1:09:30 AM	09
"M"	The month, from 1 through 12.	5/15/2014 1:45:30 PM	6
"MM"	The month, from 01 through 12.	5/15/2014 1:45:30 PM	06
"MMM"	The abbreviated name of the month.	6/15/2014 1:45:30 PM	Jun
"MMMM"	The full name of the month.	6/15/2014 1:45:30 PM	June
"s"	The second, from 0 through 59.	5/15/2014 1:45:09 PM	9
"ss"	The second, from 00 through 59.	5/15/2014 1:45:09 PM	09
"t"	The first character of the AM/PM designator.	5/15/2014 1:45:09 PM	P
"tt"	The AM/PM designator.	5/15/2014 1:45:09 PM	PM
"y"	The year, from 0 to 99.	5/15/2014 1:45:09 PM	9
"yy"	The year, from 00 to 99.	5/15/2014 1:45:09 PM	09
"yyy"	The year, with a minimum of three digits.	5/15/2009 1:45:30 PM	2009
"yyyy"	The year as a four-digit number.	5/15/2009 1:45:30 PM	2009
"yyyyy"	The year as a five-digit number.	5/15/2009 1:45:30 PM	02009
"z"	Hours offset from UTC, with no leading zeros.	5/15/2014 1:45:30 PM -07:00	-7
"zz"	Hours offset from UTC, with a leading zero for a single-digit value.	5/15/2014 1:45:30 PM -07:00	-07
"zzz"	Hours and minutes offset from UTC.	5/15/2014 1:45:30 PM -07:00	-07:00
"st"	Date ordinal (st, nd, rd and th) display from day of the date.	5/15/2014 1:45:30 PM	15th

Using the Code

Hide Shrink Copy Code

var dayNames = ['Sun', 'Mon', 'Tues', 'Wednes', 'Thurs', 'Fri', 'Satur'];
var monthNames = ['January', 'February', 'March', 'April', 'May', 'June', 
                  'July', 'August', 'September', 'October', 'November', 'December'];
Date.prototype.format = function (format) {
    var wordSplitter = /\W+/, _date = this;
    this.Date = function (format) {
        var words = format.split(wordSplitter);
        words.forEach(function(w) {
            if (typeof(wordReplacer[w]) === "function") {
                format = format.replace(w, wordReplacer[w]() );
            }
            else {
                wordReplacer['e'](w);
            }
        });
        return format.replace(/\s+(?=\b(?:st|nd|rd|th)\b)/g, "");
    };
    var wordReplacer = {
        //The day of the month, from 1 through 31. (eg. 5/1/2014 1:45:30 PM, Output: 1)
        d : function() {
            return _date.getDate();
        },
        //The day of the month, from 01 through 31. (eg. 5/1/2014 1:45:30 PM, Output: 01)
        dd : function() {
            return _pad(_date.getDate(),2);
        },
        //The abbreviated name of the day of the week. (eg. 5/15/2014 1:45:30 PM, Output: Mon)
        ddd : function() {
            return dayNames[_date.getDay()].slice(0,3);
        },
        //The full name of the day of the week. (eg. 5/15/2014 1:45:30 PM, Output: Monday)
        dddd : function() {
            return dayNames[_date.getDay()] + 'day';
        },
        //The tenths of a second in a date and time value. (eg. 5/15/2014 13:45:30.617, Output: 6)
        f : function() {
            return parseInt(_date.getMilliseconds() / 100) ;
        },
        //The hundredths of a second in a date and time value.  
        //(e.g., 5/15/2014 13:45:30.617, Output: 61)
        ff : function() {
            return parseInt(_date.getMilliseconds() / 10) ;
        },
        //The milliseconds in a date and time value. (eg. 5/15/2014 13:45:30.617, Output: 617)
        fff : function() {
            return _date.getMilliseconds() ;
        },
        //If non-zero, The tenths of a second in a date and time value. 
        //(eg. 5/15/2014 13:45:30.617, Output: 6)
        F : function() {
            return (_date.getMilliseconds() / 100 > 0) ? parseInt(_date.getMilliseconds() / 100) : '' ;
        },
        //If non-zero, The hundredths of a second in a date and time value.  
        //(e.g., 5/15/2014 13:45:30.617, Output: 61)
        FF : function() {
            return (_date.getMilliseconds() / 10 > 0) ? parseInt(_date.getMilliseconds() / 10) : '' ;
        },
        //If non-zero, The milliseconds in a date and time value. 
        //(eg. 5/15/2014 13:45:30.617, Output: 617)
        FFF : function() {
            return (_date.getMilliseconds() > 0) ? _date.getMilliseconds() : '' ;
        },
        //The hour, using a 12-hour clock from 1 to 12. (eg. 5/15/2014 1:45:30 AM, Output: 1)
        h : function() {
            return _date.getHours() % 12 || 12;
        },
        //The hour, using a 12-hour clock from 01 to 12. (eg. 5/15/2014 1:45:30 AM, Output: 01)
        hh : function() {
            return _pad(_date.getHours() % 12 || 12, 2);
        },
        //The hour, using a 24-hour clock from 0 to 23. (eg. 5/15/2014 1:45:30 AM, Output: 1)
        H : function() {
            return _date.getHours();
        },
        //The hour, using a 24-hour clock from 00 to 23. (eg. 5/15/2014 1:45:30 AM, Output: 01)
        HH : function() {
            return _pad(_date.getHours(),2);
        },
        //The minute, from 0 through 59. (eg. 5/15/2014 1:09:30 AM, Output: 9
        m : function() {
             return _date.getMinutes()();
        },
        //The minute, from 00 through 59. (eg. 5/15/2014 1:09:30 AM, Output: 09
        mm : function() {
            return _pad(_date.getMinutes(),2);
        },
        //The month, from 1 through 12. (eg. 5/15/2014 1:45:30 PM, Output: 6
        M : function() {
            return _date.getMonth() + 1;
        },
        //The month, from 01 through 12. (eg. 5/15/2014 1:45:30 PM, Output: 06
        MM : function() {
            return _pad(_date.getMonth() + 1,2);
        },
        //The abbreviated name of the month. (eg. 5/15/2014 1:45:30 PM, Output: Jun
        MMM : function() {
            return monthNames[_date.getMonth()].slice(0, 3);
        },
        //The full name of the month. (eg. 5/15/2014 1:45:30 PM, Output: June)
        MMMM : function() {
            return monthNames[_date.getMonth()];
        },
        //The second, from 0 through 59. (eg. 5/15/2014 1:45:09 PM, Output: 9)
        s : function() {
            return _date.getSeconds();
        },
        //The second, from 00 through 59. (eg. 5/15/2014 1:45:09 PM, Output: 09)
        ss : function() {
            return _pad(_date.getSeconds(),2);
        },
        //The first character of the AM/PM designator. (eg. 5/15/2014 1:45:30 PM, Output: P)
        t : function() {
            return _date.getHours() >= 12 ? 'P' : 'A';
        },
        //The AM/PM designator. (eg. 5/15/2014 1:45:30 PM, Output: PM)
        tt : function() {
            return _date.getHours() >= 12 ? 'PM' : 'AM';
        },
        //The year, from 0 to 99. (eg. 5/15/2014 1:45:30 PM, Output: 9)
        y : function() {
            return Number(_date.getFullYear().toString().substr(2,2));
        },
        //The year, from 00 to 99. (eg. 5/15/2014 1:45:30 PM, Output: 09)
        yy : function() {
            return _pad(_date.getFullYear().toString().substr(2,2),2);
        },
        //The year, with a minimum of three digits. (eg. 5/15/2014 1:45:30 PM, Output: 2009)
        yyy : function() {
            var _y = Number(_date.getFullYear().toString().substr(1,2));
            return _y > 100 ? _y : _date.getFullYear();
        },
        //The year as a four-digit number. (eg. 5/15/2014 1:45:30 PM, Output: 2009)
        yyyy : function() {
            return _date.getFullYear();
        },
        //The year as a five-digit number. (eg. 5/15/2014 1:45:30 PM, Output: 02009)
        yyyyy : function() {
            return _pad(_date.getFullYear(),5);
        },
        //Hours offset from UTC, with no leading zeros. (eg. 5/15/2014 1:45:30 PM -07:00, Output: -7)
        z : function() {
            return parseInt(_date.getTimezoneOffset() / 60) ; //hourse
        },
        //Hours offset from UTC, with a leading zero for a single-digit value. 
        //(e.g., 5/15/2014 1:45:30 PM -07:00, Output: -07)
        zz : function() {
            var _h =  parseInt(_date.getTimezoneOffset() / 60); //hourse
            if(_h < 0) _h =  '-' + _pad(Math.abs(_h),2);
            return _h;
        },
        //Hours and minutes offset from UTC. (eg. 5/15/2014 1:45:30 PM -07:00, Output: -07:00)
        zzz : function() {
            var _h =  parseInt(_date.getTimezoneOffset() / 60); //hourse
            var _m = _date.getTimezoneOffset() - (60 * _h);
            var _hm = _pad(_h,2) +':' + _pad(Math.abs(_m),2);
            if(_h < 0) _hm =  '-' + _pad(Math.abs(_h),2) +':' + _pad(Math.abs(_m),2);
            return _hm;
        },
        //Date ordinal display from day of the date. (eg. 5/15/2014 1:45:30 PM, Output: 15th)
        st: function () {
            var _day = wordReplacer.d();
            return _day < 4 | _day > 20 && ['st', 'nd', 'rd'][_day % 10 - 1] || 'th';
        },
        e: function (method) {
            throw 'ERROR: Not supported method [' + method + ']';
        }
    };
    _pad = function (n, c) {
        if ((n = n + '').length < c) {
            return new Array((++c) - n.length).join('0') + n;
        }
        return n;
    }
    return this.Date(format);
}

In this section, I will show you how to use Date() object with custom formatting.

The "dd" Custom Format

The "dd" custom format string represents the day of the month as a number from 01 through 31.

A single-digit day is formatted with a leading zero. The following example includes the "dd" custom format specifier in a custom format string.

Hide Copy Code

date = new Date();
console.log(date.format('dd st-MMM-yyyy'));  //Output: "15th-May-2014"

The "dddd" Custom Format

The "dddd" custom format string represents the full name of the day of the week.

A day name of the day of week. The following example includes the "dddd" custom format specifier in a custom format string.

Hide Copy Code

date = new Date();
console.log(date.format('dddd, dd/M/yy'));  //Output: "Thursday, 15/5/14"

The "ff" Custom Format

The "ff" custom format specifier represents the two most significant digits of the seconds fraction; that is, it represents the hundredths of a second in a date and time value.

The following example includes the "ff" custom format specifier in a custom format string.

Hide Copy Code

date = new Date();
console.log(date.format('dddd, dd/M/yy hh:mm:ss.ff'));  //Output: "Thursday, 15/5/14 04:51:28.49"

The "HH" Custom Format

The "HH" custom format specifier (plus any number of additional "H" specifiers) represents the hour as a number from 00 through 23; that is, the hour is represented by a zero-based 24-hour clock that counts the hours since midnight. A single-digit hour is formatted with a leading zero.

The following example includes the "HH" custom format specifier in a custom format string.

Hide Copy Code

date = new Date();
console.log(date.format('HH:mm:ss'));  //Output: "16:54:51"

The "tt" Custom Format

The "t" custom format specifier represents the first character of the AM/PM designator.

The following example includes the "tt" custom format specifier in a custom format string.

Hide Copy Code

date = new Date();
console.log(date.format('dd-MM-y HH:mm:ss tt'));  //Output: "15-05-14 17:00:20 PM"

The "st" Custom Format

The "st" custom format string represents the ay ordinal of the day (eg. st, nd, rd and th).

The following example includes the "st" custom format specifier in a custom format string.

Hide Copy Code

date = new Date();
console.log(date.format('ddd, dd st-MMM-yyyy HH:mm:ss tt zz'));  //Output: 
                                                                 //"Thu, 15th-May-2014 17:06:37 PM -05"

Points of Interest

Using the above date and time format utility, you can generate more than thousands of various formatting strings as you like or as per your requirements.

Please feel free to ask me if you would require any help for the same.

Your valuable feedback, comments, suggestions are highly appreciated.

Ref: https://www.codeproject.com/Articles/773356/Date-and-Time-Formatting-in-JavaScript-like-NET-Cs

SOLID Design principles with C# practical examples

2019-02-07T01:07:00.001-08:00

Do you really want to develop the extensible, flexible and mobile code while working on the project in your organization. If yes then you should be aware of the SOLID design principles. In this article I will cover SOLID design principles with the help of practical and real world examples which we can relate to our own application.

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Before going further have you ever encountered this kind of conversation with your colleague in your organization

Developer 1: I am really worried.

Developer 2: What Happened

Developer 1: Whenever I fix a bug in the system, some other functionality brakes which I have not at all touched.

Developer 2: hmm..Have you used SOLID principles while designing and developing the application ?

Developer 1: No, what are they?

SOLID Principles

Some important point about SOLID design principles.

Generally speaking, SOLID state of matter can be brittle. But while talking about code we are not aiming for brittleness of code.
As far as software designing is concerned, SOLID should be used where code can change shape.
SOLID can come to rescue when all the requirements are not upfront while developing code.
SOLID is not a framework
SOLID principle is not a library.It is not technology bound. It is not pattern.
Most of the code written today, though they are written in object oriented way but they are not object oriented and more or less procedural. Writing code in OO language is not a guarantee that the code will be OO.
But we can make our code OO by using solid principles.We can more productive by using SOLID.
Code is more maintainable and understandable.When code suffer from design smell then SOLID is answer.

How SOLID principles Solves read world Application Problems

Some of the design smell I which I want to discuss here are.

Rigidity – The design is difficult to change. Without proper use of abstraction and interface the design becomes very rigid. For each and every small change in the functionality we have to test whole logic from start.
Fragility – Design is easy to break. As discussed with a small change there are very high chances of the whole design going for a toss.
Immobility – The design is difficult to reuse. Or rather we cannot easily extend the current design.
Viscosity – It is difficult to do the right thing.
Needless Complexity – Over design.

Following are the five SOLID design principles which we should be ware of

S – Single responsibility principle(SRP)

O – Open closed principle(OCP)

L – Liskov Substitution principle(LSP). How polymorphism should work.

I – Interface segregation Principle(ISP). How interface should be designed.

D- Dependency inversion principle(DIP) which describes principle between abstraction and concrete types.

There is no built-in order to these principles. Just because Single responsibility come first does not mean that it is more important than any other principle in C#. All of the parts of the SOLID are equally important to be implemented in the code. It is like that just because it is a nice acronym. As seen in the below figure all the five principles are related to each other.

Robert C. martin the inventor of the Design principle initially had only three principles designed. But later someone added two more principle and it came out to be a nice acronym.

Apart from the order, one more thing which is important is the relationship among all these principle.

Single Responsibility Principle

A class should have only single responsibility. A single reason to change.
Based on separation of concerns.
Vary each concern independently of other concern.
Each class should be designed to do one thing and it should do it well.
The size of the classes become shorter. This makes code easily understandable.

I will discuss the example of the single responsible principle along with the Open closed principle next.

Open Closed Principle

Writing something very specific to solve some specific problem can lead to writing same code multiple time which in turn results in code duplication
Code duplication leads to maintainability problem.
Reused abstraction principle – if we have multiple abstractions which are not being used by the concrete class then it is a sign of poor designing and abstractions.
Interfaces are not designed but they are discovered as the system grows.
Start with the concrete behaviour and discover the abstraction as commonality emerges.
Rule of three – Unless and until we have three places where we think that the code is same, it is generally not advised to abstract out the functionality.
Open for extensibility but closed for modification. If we have a class which is being used by other clients, that class should be open for extensibility. The only reason to change the class should be to fix a bug in the class.
We should favor Composition over inheritance which I will discuss in next principles.
We can make a class open for extensible is by adding virtual keyword to the methods of the class.

Lets see an example of the C# shape class which is not using any of the design principles.

Simple Class

C#

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 public class Shape

    {

        //TODO add more shapes if needed

        public const int SQUARE = 1;

        public const int CIRCLE = 2;

        public const int EQUILATERAL_TRIANGLE = 3;

        private readonly double width;

        public int type = -1;

        public Shape(int type, double width)

        {

            this.type = type;

            this.width = width;

        }

        public double getArea()

        {

            switch (type)

            {

                case SQUARE:

                    return width * width;

                case CIRCLE:

                    return Math.PI * (width / 2) * (width / 2);

                case EQUILATERAL_TRIANGLE:

                    return (Math.Sqrt(3) / 4) * width * width;

            }

            throw new SystemException("Can`t compute area of unknown shape");

        }

        public static double CalculateTotalArea(List<Shape> shapes)

        {

            double totalArea = 0;

            foreach (var shape in shapes)

            {

                for (int i = 0; i < shapes.Count; i++)

                {

                    if (shapes[i].type == SQUARE)

                    {

                        totalArea += shapes[i].getArea();

                    }

                    if (shapes[i].type == CIRCLE)

                    {

                        totalArea += shapes[i].getArea();

                    }

                    if (shapes[i].type == EQUILATERAL_TRIANGLE)

                    {

                        totalArea += shapes[i].getArea();

                    }

                }

            }

            return totalArea;

        }

    }

Though there are many short coming in this class. But what is the basic shortcoming which you can see. For every shape added we have to change the GetArea() method as well as the CalculateTotalArea() method. There are many reason for the class to change. It means the class is violating the SRP.

Again whenever we have to add a new shape we have to add a new const as well as add a switch and if statement in both of the methods. It means that the class is not closed for modifications and not easily extend able.

Now lets redesign it. We have created a new system in C# language.

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    public interface IShape

    {

        int Width { get; set}

        double GetArea();         

    }

    public class Sqaure :IShape

    {

        private int width;

        public Sqaure() 

        {            

        }

        public int Width

        {

            get            {                return width;            }

            set            {                width = value;            }        

        }

        public double GetArea()

        {

            double area = Width * Width;           

            return area;

        }       

    }

    public class Circle : IShape

    {       

        private int width;

        public Circle()

        {          

        }

        public int Width

        {

            get            {                return width;            }

            set            {                width = value;            }        

        }

        public double GetArea()

        {

            double area = Math.PI * (double)((double)Width / (double)2) * 

                                     (double)((double)Width / (double)2);           

            return area;

        }       

    }

    public interface IAreaCalculator

    {

        double CalculateArea(IList<IShape> shapes);

    }  

    public class AreaCalculator: IAreaCalculator

    {

         public double CalculateArea(IList<IShape> shapes)

         {

              double totalArea = 0;

              foreach (IShape shape in shapes)

              {

                  totalArea += shape.GetArea();

              }

              return totalArea;

         }

    }

In the above code I have redesigned the class and abstracted out the functions. Now we can see that each and every class is responsible for one and only one functionality. If we want to add a new Shape, we have to only derive from the IShape class and IAreaCalculator will do the needful of calculating the total area of all the shapes.

The above code is following the SRP as said. It also follows the ORP as there is no need to change the AreaCalcualator class whenever a new shape is added. At run time it will take care of all the implementations of the IShape interface.

Liskov Substitution Principle

It talks about polymorphism.
Named after barbara liskov, in 70’s
Derived types must be substituted for base types.
Client can consume any implementation without changing the correctness of the system
We can change the behaviour of the system because polymorphism is all about changing the behaviour.
Correctness of the system can be said as the implementation of the interface A should not crash the application. Similarly implementation of the interface B should also not crash the application. But any implementation of the system is crashing the system that is not the correctness of the system. The implementation is the lowest common denominator when we talk about the correctness of the system. The system can also behave in wrong way if we have a wrong way of the implementation.

Breaking the LSP:

When we get the NotSupportedException.
Best example is ICollection<T> in .NET framework. It implements from IEnumerable<T> which means we can enumerate the collection.
One interesting implementation is ReadOnlyCollection<T>. Once the collection is created it cannot be changed. We cannot add or remove the items from the collection.
Add , clear and Remove methods throw the NotSupportedExceptions. It can break the correctness of the system because suppose if one part of the client is accepting only the ICollection<T> and it was working fine with List<T> implementation . But if we substitute it with ReadOnlyCollection, it will break for Add, Clear and Remove methods and thus putting the correctness of the system in jeopardy.
Please check the below C# code. Here Add() method is present for the readOnlyList but it throws the exception. Though the Add method is added implicitly to the ReadOnlyCollection.

C# LSP Violation

If we have NotSupportedException in the code base, it violates the LSP principle.
Downcast can also break LSP. Suppose if we are down casting the ICollection to List<T> and performing some operation. In the above scenario the ReadOnlyCollection will throw the exception. Check the below C# code for down casting example.

C#

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    ReadOnlyCollection<Person> readOnlyList = new ReadOnlyCollection<Person>(person);

    var newCollection = readOnlyList as ICollection<Person>;

    newCollection.Add(new Person() { Name = "New Pserson" });

Extraction of the interface could violate LSP.

Example.

C#

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    public interface IShape

    {

        int Width { get; set; }

        double GetArea();

        double GetVolume();

    }

    public class Sqaure : IShape

    {

        private int width;

        public Sqaure()

        {

        }

        public int Width

        {

            get { return width; }

            set { width = value; }

        }

        public double GetArea()

        {

            double area = Width * Width;

            return area;

        }

        public double GetVolume()

        {

            throw new NotImplementedException();

        }

    }

    public class Cube : IShape

    {

        private int width;

        public int Width

        {

            get { return width; }

            set { width = value; }

        }

        public double GetArea()

        {

            return 6 * Width * Width;

        }

        public double GetVolume()

        {

            return Width * Width * Width;

        }        

    }

    public interface IVolumeCalculator

    {

        double CalculateVolume(IList<IShape> shapes);

    }

    public class VolumeCalculator : IVolumeCalculator

    {

        public double CalculateVolume(IList<IShape> shapes)

        {

            double totalVolume = 0;

            foreach (var shape in shapes)

            {

                totalVolume += shape.GetVolume();

            }

            return totalVolume;

        }

    }

We have decided to add more shapes to our system. Please check the above C# code. But these shapes are three dimensional. These shapes can have Volume apart from the area. I have added a new method to IShape interface named GetVolume.

I have created a new shape named Cube which derived from IShape. We have a new class named VolumeCalculator which calculates the total volume of all the shapes.

But since we have added new method to IShape interface, we have to implement the method to existing shapes. As I have done for Square, but it is not implemented.

Now if the collection which are sending to the VolumeCalculator contains any of the 2D shapes, it will throw a NotSupportedException for them. This is the violation of LSP in SOLID design principles.

Interface Segregation Principle(ISP)

ISP is SOLID design principle which is used to help us achieve the LSP by having more granularity.
Clients should not depend on methods they do not use. As we have see in the previous code example. VolumeCalculator should not depend on the GetVolume methods of the classes.
Interface are introduced to achieve loose coupling and its not the classes that use the interfaces but clients are the one who use interfaces.
Clients define the interface and there is no need for an client to define a method in the interface if the client doesn’t need the method in the interface.
Prefer role based interfaces over header interfaces. Header interfaces are created by abstracting out of the existing classes as we have done in designing previous system.
If client need to define the interface it only need to define a very few methods in the interface. These are role interface.
There are many ways by which we can extend the functionality of the class e.g. by inheritance, by using generics or by using extension methods.
But there are very less way by which we can reduce the methods in the class. Indeed there is only one way and that is ISP.

C#

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   public interface IShape

    {

        int Width { get; set; }

    }

    public interface IVolume

    {

        double GetVolume();

    }

    public interface IArea

    {

        double GetArea();

    }

    public class Sqaure : IShape, IArea

   {

       private int width;

       public Sqaure()

       {

       }

       public int Width

       {

          get { return width; }

          set { width = value; }

       }

       public double GetArea()

      {

        double area = Width * Width;

        return area;

      }

   }

    public class Cube : IShape, IArea, IVolume

    {

        private int width;

        public int Width

        {

            get { return width; }

            set { width = value; }

        }

        public double GetArea()

        {

            return 6 * Width * Width;

        }

        public double GetVolume()

        {

            return Width * Width * Width;

        }        

    }

    public interface IVolumeCalculator

    {

        double CalculateVolume(IList<IVolume> shapes);

    }

    public class VolumeCalculator : IVolumeCalculator

    {

        public double CalculateVolume(IList<IVolume> shapes)

        {

            double totalVolume = 0;

            foreach (var shape in shapes)

            {

                totalVolume += shape.GetVolume();

            }

            return totalVolume;

        }

    }

The above C# code is self explanatory. You can notice how I have segregated the interfaces to achieve ISP.

Dependency Inversion Principle

The important points to keep in mind while developing the solutions which meet the criteria set by DIP are.

High-level modules should not depend on low-level modules. Both should depend on abstractions.
Abstractions should not depend on details. Details should depend on abstractions.
Implementation of the DIP can also involve Composite pattern and Decorator pattern which I will discuss in later articles.

Now as per the design of the previous code suppose the VolumeCalculator class is also used to display a message as shown in the below code

C#

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    public class VolumeCalculator : IVolumeCalculator

    {

        Messanger messager;

        public VolumeCalculator()

        {

            messager = new Messanger();

        }

        public double CalculateVolume(IList<IVolume> shapes)

        {

            double totalVolume = 0;

            foreach (var shape in shapes)

            {

                totalVolume += shape.GetVolume();

            }

            messager.Message(totalVolume);

            return totalVolume;

        }

    }

    public class Messanger

    {

        public void Message(double volume)

        {

            Console.WriteLine("The total Volume is " + volume);

        }

    }

Now if some other client comes and they want the message to be displayed in Other Language e.g. French. Is our code extensible? No, not at all. This scenario can be handled by abstracting out the Message() functionality as shown in the below code.

C#

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  public class VolumeCalculator : IVolumeCalculator

    {

        IMessanger messager;

        public VolumeCalculator(IMessanger msg)

        {

            messager = msg;

        }

        public double CalculateVolume(IList<IVolume> shapes)

        {

            double totalVolume = 0;

            foreach (var shape in shapes)

            {

                totalVolume += shape.GetVolume();

            }

            messager.Message(totalVolume);

            return totalVolume;

        }

    }

    public interface IMessanger

    {

        void Message(double volume);

    }

    public class EnglishMessanger: IMessanger

    {

        public void Message(double volume)

        {

            Console.WriteLine("The total Volume is " + volume);

        }

    }

    public class FrenchMessanger : IMessanger

    {

        public void Message(double volume)

        {

            Console.WriteLine("Le volume total est " + volume);

        }

    }

In the above code VolumeCalculator class is determining at run time which instance to use.

Conclusion:

In this article I have discussed all the SOLID principles with practical C# examples. I hope this will help you to have a better understanding of SOLID principles which will eventually help you to code better.

Ref: https://www.dotnetforall.com/solid-design-principles-examples/