Electronic Screw

Passing parameters to javascript methods from controls in GridView

gnineth — Sun, 27 Jan 2008 22:44:00 -0700

Sometimes we may need to pass values (server side) to the client functions (javascript) on the GridView controls. In such case, we can attach the javascript functions to the GridView controls from code-behind using the RowDataBound event of the GridView.

I have a GridView that is bound to an ObjectDataSource, and I have converted one of the column into a TemplateField, so that I can access the controls in the underlying templates.

[code:html]
    <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" DataKeyNames="CountryId"
        DataSourceID="ObjectDataSource1">
        <Columns>
            <asp:TemplateField HeaderText="TestColumn">
                <ItemTemplate>
                    <asp:Button ID="Button1" runat="server" Text='Click Me'></asp:Button>
                </ItemTemplate>
            </asp:TemplateField>

[/code]

To attach a javascript function the Button1, we add the attributes in the RowDataBound event ( I use RowDataBound event because, you can access the underlying DataItem of the row, so that we can pass the database values to the javascript function. You can also use the RowCreatedEvent of the GridView to add the attributes.)

[code:c#]
    protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
    {
        if (e.Row.RowType == DataControlRowType.DataRow)
        {
            string paramValue = "somevalue";
            Button btnTest = (Button)e.Row.FindControl("Button1");
            if (btnTest != null)
                btnTest.Attributes.Add("onClick", "javascript:methodName('" + paramValue + "');");
        }
    }
[/code]

This way you can pass parameters from code-behind to javascript methods for the controls inside a GridView. My next post will be on how to access the underlying data in the RowDataBound event which helps in manipulating and customizing the way data is presented

E Screw

Saving Master-Child entries using LINQ

gnineth — Sat, 26 Jan 2008 16:08:00 -0700

LINQ provides an easy way to save the master-child data and you need not worry about the PK/FK relations or manage them manually. Let us see how to save the Country/City information using LINQ

Create an instance of the DataContext you are working on. DataContext will be created when you create a new Linq To Sql file (.dbml). Drag the tables Country and City onto the designer and the relation will be created automatically. You can also see the filed names of the corresponding tables shown as properties the classes.

[code:c#]
ExampleDataContext db = new ExampleDataContext();
[/code]

Create the new Country and City

[code:c#]

// create a new country
Country country = new Country();
country.Name = "myCountry";

// create the cities
City city1 = new City();
city1.Name = "myCity1";

City city2 = new City();
city2.Name = "myCity2";

// relate the cities with the new country created
// because of the PK/FK relation, you will find the cities collection as a property of the Country which is automatically created by LINQ for you
country.Cities.Add(city1);
country.Cities.Add(city2);

// add the country to the database and save the changes
db.Countries.Add(country);
db.SubmitChanges();
[/code]

E Screw

Working with ASP.NET AJAX ModalPopupExtender

gnineth — Fri, 25 Jan 2008 22:20:00 -0700

Recently I wrote an article about using ModalPopupExtender at www.aspalliance.com

Check the article here www.aspalliance.com/1509

E Screw

Preventing Duplicate Record Insertion on Page Refresh

gnineth — Mon, 12 Nov 2007 18:48:00 -0700

I have found a good article on preventing the duplicate record insertion on page refresh by Terri Mortan. Check the article here http://aspalliance.com/687

E Screw

Page generation time using Stopwatch class

gnineth — Sun, 22 Jul 2007 08:27:00 -0700

Using the Stopwatch class (available from .NET 2.0) we can display the amount of time taken to process the page.
Stopwatch gets you the most accurate time elapsed in milliseconds or ticks and the code below displays the time taken for the entire page life cycle to be processed.

Stopwatch class is available in System.Diagnostics namespace.


[code:c#]public partial class TestPage : System.Web.UI.Page {      
// when the page is instantiated we start our stopwatch      
System.Diagnostics.Stopwatch sw = System.Diagnostics.Stopwatch.StartNew();        
protected void Page_Load (object sender, EventArgs e)  {            
// your page load code      
}      
// override the Render method      
protected override void Render (HtmlTextWriter writer)  {            
// get the total time elapsed. this will be in milliseconds            
// and I converted it to seconds            
float _seconds = ((float)sw.ElapsedMilliseconds/1000);            
// display the information in a label            
this.lblPageGeneratedIn.Text = "Page generated in " + _seconds.ToString() + " seconds";            
base.Render(writer);      
}class="kwd">}[/code]

E Screw

Microsoft Silverlight

gnineth — Thu, 03 May 2007 04:43:00 -0700

Microsoft Silverlight is a cross-browser, cross-platform plugin for delivering the next generation of .NET based media experiences and rich interactive applications for the Web. Silverlight offers a flexible programming model that supports JavaScript, .NET, and other languages.

To get started, tutorials, downloads visit : http://silverlight.net/GetStarted/

For complete source code used in the get started video visit : http://delay.members.winisp.net/SilverlightAirlinesDemo/SilverlightAirlinesDemo.zip

A demo of the Silverlight Airlines can be viewed at : http://delay.members.winisp.net/SilverlightAirlinesDemo/

Source: http://blogs.msdn.com/delay/archive/2007/05/01/the-web-just-got-even-better-silverlight-announced-at-mix07.aspx

Get Started!
E Screw

Filters and Transitions

gnineth — Wed, 02 May 2007 15:10:00 -0700

I have found a good article on using the filters and transitions for use in web pages using the CSS and JavaScript. Check this link http://msdn2.microsoft.com/en-us/library/ms532847.aspx

E Screw

Filters and Transitions

gnineth — Wed, 02 May 2007 10:10:00 -0700

I have found a good article on using the filters and transitions for use in web pages using the CSS and JavaScript. Check this link http://msdn2.microsoft.com/en-us/library/ms532847.aspx

E Screw

Get DayNames in a given Culture

gnineth — Mon, 05 Mar 2007 05:14:00 -0700

Sometimes we may need to have the day names in a week for a given culture. With ASP.NET CultureInfo class you can loop through the DateTimeFormat.DayNames and get them. Here is the example of it

[code:c#]
using System.Globalization;

CultureInfo ci = new CultureInfo("ar-ae"); // gets the day names of arabic, arab emirates
foreach (string day in ci.DateTimeFormat.DayNames)
Response.Write(day + "<br/>");
[/code]

Depending on the culture you want, you can get the CultureInfo reference for that corresponding culture. The DateTimeFormat also provides other values like month names, first day of week etc.,

- Electronic Screw

Using GeoIPService of WebServiceX

Wed, 14 Feb 2007 17:00:00 -0700

WebserviceX.net provides a wide range of webservices, that can be used freely in development. GeoIPService is one webservice available with them that can be used to display the users country information that he/she was browsing from.

A small example on how to use the webservice (GeoIPService) in asp.net development. Create a new Project in Visual Studio. Right click on the project in the Solution Explorer and Click Add Web reference. In the Add Web Reference dialog box, enter the following url in the URL: box and click Go button.

http://www.webservicex.net/geoipservice.asmx?wsdl

If the webservice is found, the information will be displayed in the respective boxes. Click on Add Reference button. By default the web service will be added with the following namespace net.webservicex.www

The required webserive files will be added automatically in the App_WebReferences folder created under the root of your application. You will see the geoipservice.discomap and geoipservice.wsdl added under the net >> webservicex >> www folder.

Note: geoipservice.discomap and geoipservice.wsdl are the discovery and webservice definition language files, that provides the necessary methods and classes.

Now , we use the classes and methods provided by the webservice in our page to display the country information like name etc..

Here is a sample listing on how to use in the aspx page (C# code)

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using net.webservicex.www;
using System.Text;

public partial class _Default : System.Web.UI.Page
{
   protected void Page_Load(object sender, EventArgs e)
   {
      // set the current country name
      StringBuilder _stringToDisplay = new StringBuilder();
      GeoIPService _gipService = new GeoIPService();
      GeoIP _geoIP = _gipService.GetGeoIP(Request.UserHostAddress.ToString());
      _stringToDisplay.Append(_geoIP.CountryName);
      _stringToDisplay.Append(" [" + _geoIP.CountryCode + "] ");

      lblCountryName.Text = _stringToDisplay.ToString();
   }
}

A sample of this implementation can be seen in my home page http://www.g9th.com in the top right corner.

-Electronic Screw

Creating a CascadingDropDown using ASP.NET AJAX

gnineth — Mon, 12 Feb 2007 05:32:00 -0700

I have seen in many forums people asking questions as “how to populate the cascadingdropdown with values from database". Although there was a sample provided for the same in the ASP.NET AJAX ControlToolkit, most of the learners (novice) following the walkthrough given at http://ajax.asp.net/ajaxtoolkit/Walkthrough/CCDWithDB.aspx get struck at the CarsTableAdapters used in the webservice.

So, I have posted an article Creating a CascadingDropDown Using AJAX at aspalliance.com which explains the step-by-step procedure on how to create CascadingDropDown using database values with the help of Microsoft SQL Server 2005 Express Edition.

E Screw

Sort ListItems in ASP.NET

gnineth — Sun, 11 Feb 2007 12:41:00 -0700

Sorting of ListItems inside a Dropdownlist or Listbox is not provided by default .net framework. Either you need to sort your items at the database level (using order by) if the lists are binded with a datasource from database, or you need to write your own class which implements the IComparer interface and override the Compare method stub.

I write an example on how you write the class and override the Compare method. The compare method takes as input, 2 objects (x and y) and performs a comparison on the two objects. Passing objects as parameters will help in sorting custom object types as well as datatypes like int string etc., The function returns 0 if the two objects are equal, a number less than zero if x is less than y, and a number greater than zero if x is greater than y.

A class ListItemComparer which implements the IComparer interface and overrides the Compare method.

[code:c#]
// A class which implements the IComparer interface.
public class ListItemComparer : IComparer
{
    public int Compare(object x, object y)
    {
        ListItem li_x = (ListItem)x;
        ListItem li_y = (ListItem)y;
        CaseInsensitiveComparer c = new CaseInsensitiveComparer();
        return c.Compare(li_x.Text, li_y.Text);
    }
}
[/code]

Now, we can have a generalized static method, which takes the Dropdownlist as input and sorts it accordingly.

[code:c#]
public static void SortDropDownList(DropDownList dlList)
{
    ArrayList arl = null;
    if (dlList.Items.Count > 0)
    {
        arl = new ArrayList(dlList.Items.Count);
        foreach (ListItem li in dlList.Items)
            arl.Add(li);
     }
    arl.Sort(new ListItemComparer());
    dlList.Items.Clear();
    for (int i = 0; i < arl.Count; i++)
        dlList.Items.Add(arl[i].ToString());
}
[/code]

Now you can use this method to sort any dropdownlist by passing it to the above method.

E Screw

Enter key on Textbox Control

gnineth — Sun, 11 Feb 2007 10:03:00 -0700

To enable the enter key on a textbox, to get the functionality of clicking a button, write the javascript. If you have only one button, and by setting the AutoSubmitBehavior to True, you can achieve this, but when you have multiple buttons, when the user press the Enter key, the first focused button is clicked.

With javascript the enter key code can be trapped. The following code will fire the enter key event, on the body.

<body onkeydown="if(event.keyCode == 13){document.getElementById('btnSubmit').click();}">
...
<asp:Button id="btnSubmit" runat="server" Text="Submit"></asp:Button>

If you want to trap the enter key on a textbox use the following

<head>
   <script language="javascript">
       function doEnterKey()
{
if ((event.which && event.which == 13) || (event.keyCode && event.keyCode == 13))
{
document.form1.submit();
            }
        }
   </script>
</head>
<body>
   <form id="form1" runat="server">
      <asp:TextBox id="Text1" runate="server" />
   </form>
</body>
</html>

in Page_Load procedure in code-behind file write the following code

submit1.Attributes.Add("onfocus","javascript:doEnterKey();")
Text1.Attributes.Add("onchange","javascript:doEnterKey();")

E Screw

String formats in C#

gnineth — Tue, 30 Jan 2007 06:33:00 -0700

I have found a good article by Steve Tibbett for string formatting.
Check this link http://www.stevex.org/dottext/articles/158.aspx

E Screw

Trust levels in ASP.NET Application

gnineth — Wed, 27 Dec 2006 02:19:00 -0700

When you are hosting your application in a shared hosting environment, you need to think about the trust levels that you need to set for your application.

Apart from the security to your web application and the files ASP.NET provides, trust levels are those, which are used to sucure the files and application in the hosting environment. The trust levels are set in the web.config file and can be set at machine, site and application levels.

What is Trust?
The application runtime, can be set to configure trust levels, which are used to contrain what an application can do. That is, if an application is running on full trust, it means, it allows the native code to execute, can look at a process, to find or corrupt or delete data from other applications. A trust level of minimum means, its a highly restrictive and a full trust means, there are no restrictions at all. The default trust level for asp.net applications is full trust.

In a full trust level application, its even possible to walk through the directories, retrieve a listing of files in specified folder outside of the root where the code executes.

With medium trust level, asp.net places a number of restrictions on the application. The application file access is restricted within the virtual directory where the application resides.

Trust level specification in web.config

<trust level="[Full|High|Medium|Low|Minimal]" originUrl="URL"processRequestInApplicationTrust = "[True|False]" />

For more information on trust level check this link: trust element (ASP.NET Settings Schema)