Prajeesh's Tech blog

Creating a Nested Gridview Control

noreply@blogger.com (prajeesh) — Tue, 03 Nov 2009 11:02:00 +0000

Working with Gridview inside Gridview.

Grid view is a very useful and easier to use data presentation control in asp.net it is having lots of default features that we can set very easily, but in some of the projects you may need to show a master client relationship to the users For eg:- List of students who are studying in different departments.
We can handle this situation by using nested grid views, ie a Gridview inside a Gridview.
Microsoft is providing a solution for this situation msdn website , see the link : http://msdn.microsoft.com/en-us/library/aa992038(VS.80).aspx

I think Microsoft's solution contains lot of steps to complete the process, I done a workaround on this and come up with a solution, let me explain the tasks in step by step with an example.
Step 1:
Create a gridview named gvDepartments and add a Template Field in it.
Step 2:
Inside the Template Field'd Item Template add another gridview called gvStudents.
Step 3:
Add following code in gvStudents grid view
DataSource ='<%# GetStudentInfo( Convert.ToInt16(Eval("Department_Id")) ) %>'
Where GetStudentInfo is a server side function that returns a datatable containing the list of students based on department id.
Source of the Grid views will be like below code :


               DataKeyNames="DepartMent_Id" CellPadding="4" ForeColor="Black"

            GridLines="Vertical" BackColor="White" BorderColor="#DEDFDE"

            BorderStyle="None" BorderWidth="1px">

            

            

                

                

                <%# Container.DataItemIndex+1   %>

                

                

                

                

                    

                                                    DataSource ='<%# GetStudentInfo( Convert.ToInt16(Eval("Department_Id")) ) %>'

                            CellPadding="4" ForeColor="#333333" GridLines="None" ShowHeader="False"

                            AutoGenerateColumns="False">

                            

                            

                                

                                    

                                       <%# Container.DataItemIndex +1   %>

Step 4
Create Method to bind gvDepartments (Must contain a column named “Department_Id” as we are passing this parameter to bind gvStudents).
Step 5
Create a Method named GetStudentInfo(int department_Id) , It accepts Department_Id as parameter and returns a
datatable contains students list,(example given below) and you are done.


public DataTable StudentsByDepartment(int DepartmentId)

   {

       SqlConnection dbConnection = new SqlConnection(ConnectionString);

       DataTable dtStudentList = new DataTable();

       try

       {

           dbConnection.Open();

           SqlDataAdapter daStudents = new SqlDataAdapter();

           SqlCommand cmdSelect = new SqlCommand("SelectStudentByDep",dbConnection);

           cmdSelect.CommandType = CommandType.StoredProcedure;

           cmdSelect.Parameters.AddWithValue("@Dep", DepartmentId );

           daStudents.SelectCommand = cmdSelect;

           daStudents.Fill(dtStudentList);

       }

       catch (Exception objException)

       {

           HttpContext.Current.Response.Write(objException.Message);

       }

       finally

       {

           if (dbConnection != null && dbConnection.State == ConnectionState.Open)

           {

               dbConnection.Close();

           }

       }

       return dtStudentList;

   }

Figure: Sample output of a nested Gridview :

Maintaining scrollbar position after postback in an asp.net page

noreply@blogger.com (prajeesh) — Thu, 29 Oct 2009 12:43:00 +0000

In some situations we may need to maintain the scroll bar position when we are dealing with large pages with a button causes post back, you can use achieve this by adding MaintainScrollPositionOnPostback=”true” in @Page directive.


<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" MaintainScrollPositionOnPostback ="true"  %>

some commonly used reguler expressions

noreply@blogger.com (prajeesh) — Thu, 29 Oct 2009 05:29:00 +0000

Here is the list of some commonly used reguler expressions for validating your forms.
E-mail
^([0-9a-zA-Z]([-\.\w]*[0-9a-zA-Z])*@([0-9a-zA-Z][-\w]*[0-9a-zA-Z]\.)+[a-zA-Z]{2,9})$
URL
^(htf)tp(s?)\:\/\/[0-9a-zA-Z]([-.\w]*[0-9a-zA-Z])*(:(0-9)*)*(\/?)([a-zA-Z0-9\-\.\?\,\'\/\\\+&%\$#_]*)?$
Social Security Number
^\d{3}-\d{2}-\d{4}$
Phone number(Validates US Phone number)
^[01]?[- .]?($[2-9]\d{2}$[2-9]\d{2})[- .]?\d{3}[- .]?\d{4}$
Zip Code(Validates US Zip code)
^(\d{5}-\d{4}\d{5}\d{9})$^([a-zA-Z]\d[a-zA-Z] \d[a-zA-Z]\d)$
Currency(Non Negative)
^\d+(\.\d\d)?$
Currency(+ve or -ve)
^(-)?\d+(\.\d\d)?$
Non Negative Integer
^\d+$
For a detailed article on reguler expressions, refer : http://msdn.microsoft.com/en-us/library/ms972966.aspx

How to display latest tweet in your website using Javascript and twitter API

noreply@blogger.com (prajeesh) — Fri, 25 Sep 2009 11:17:00 +0000

Sometimes you may be want to show your latest twitter tweets in your website or blog, most of the cases you are doing this by using widgets with limited customization facilities and showing ads or links to other websites, here is an easier way to achieve this using twitter API and javascript.
Step 1:
First, decide where about on your page you want your last tweet to display. Then paste following html code there.
Step 2:
Next you need to put these 2 lines of JavaScript below the code in step 1. On the 2nd line of code where it says prajeeshkk.json, you need to replace prajeeshkk with your twitter username.

Step 3:(Optional)
You can apply css and make the div displaying the tweet stylish.

See how my tweet design looks :

Resetting all controls in an asp.net form

noreply@blogger.com (prajeesh) — Wed, 23 Sep 2009 11:06:00 +0000

In some applications we may need to reset all controls in using a single "Reset" button click, here is the c# code to achieve this.


  public  static void ResetControls(ControlCollection pagecontrols, bool txtbox, bool dropdownlist, bool label)
    {
        foreach (Control cntrl in pagecontrols)
        {
            foreach (Control mycontrols in cntrl.Controls)
            {
                if (txtbox)
                {
                    if (mycontrols is TextBox)
                    {
                        (mycontrols as TextBox).Text = string.Empty;
                    }
                }
                if (dropdownlist)
                {
                    if (mycontrols is DropDownList)
                    {
                        (mycontrols as DropDownList).SelectedIndex = 0;
                    }
                }
                if (label)
                {
                    if (mycontrols is Label)
                    {
                        (mycontrols as Label).Text = string.Empty;
                    }
                }
            }
        }
    }

We can call this function using following format if you want to clear all controls except label


FormControl.ResetControls(this.Controls, true, true, false);

SQL Query to sort stored procedure on Modified date or Created Date

noreply@blogger.com (prajeesh) — Fri, 18 Sep 2009 15:54:00 +0000

Sometimes you may need to update an online database with some stored procedure you have modified in your local system, but in most of the cases you may be confused about what are the stored procedures or tables you modified last, here is a quick solution for this.
1.Query to sort Stored Procedures on modified date.


SELECT name, create_date, modify_date,type 
FROM sys.objects
WHERE type = 'P' order by modify_date  desc

2.Query to sort Stored Procedures on created date


SELECT name, create_date, modify_date,type 
FROM sys.objects
WHERE type = 'P' order by create_date  desc

3.Query to sort user defined tables on created date


SELECT name, create_date, modify_date,type 
FROM sys.objects
WHERE type = 'u' order by create_date  desc

4.Query to sort user defined tables on modified date


SELECT name, create_date, modify_date,type 
FROM sys.objects
WHERE type = 'u' order by modify_date  desc

Scrolling page title using javascript

noreply@blogger.com (prajeesh) — Tue, 04 Aug 2009 19:55:00 +0000

In some websites you may seen animating or scrolling page titles, here is the trick to do this, just place below code between your page's <head> and </head> tags

Automatic page refresh using asp.net

noreply@blogger.com (prajeesh) — Tue, 04 Aug 2009 18:01:00 +0000

Some situations such as a freequently updating page you may need to refresh your page automatically, here is the code to achieve this.


Response.AppendHeader("Refresh", "60; URL=Default.aspx");

Here your page Default.aspx will be refreshed after 60 seconds, if you want to redirect to another page after a few seconds, replace the page 'Default.aspx' with the page you want to be redirected.

SQL Query to Delete all stored procedures in a database

noreply@blogger.com (prajeesh) — Thu, 16 Jul 2009 12:20:00 +0000

Here is the SQL query to create a stored procedure that deletes all stored procedures in a database



create procedure dropallsp as
declare @procName varchar(500)
declare cur cursor
for Select [name] from sys.procedures where [type] = 'P' and is_ms_shipped = 0 and [name] not like 'sp[_]%diagram%'
open cur
fetch next from cur into @procName
while @@fetch_status = 0
begin
exec('drop procedure ' + @procName)
fetch next from cur into @procName
end
close cur
deallocate cur

Query to drop all tables in a database

noreply@blogger.com (prajeesh) — Thu, 16 Jul 2009 12:13:00 +0000

Here is an easy way to drop all tables in a database using a single query.


exec sp_msforeachtable 'Drop table ?'

As it is an undocumented stored procedure it may be get removed any time without any notification.

Microsoft Launched new community portal for developers

noreply@blogger.com (prajeesh) — Thu, 09 Jul 2009 21:05:00 +0000

Microsoft Launched a new community portal for developers to thrive your career, this portal helps you to find a job, training, trial software's and community support for developers.
URL is : http://www.microsoft.com/click/thrivedev/

Page redirection using javacript and HTML

noreply@blogger.com (prajeesh) — Thu, 09 Jul 2009 20:24:00 +0000

In ASP.net we are using Response.Redirect or Server.Transfer for redirect to another page, this Redirection can also be done using Javascript or HTML
javascript:


 < language="javascript">
         window.location = "YourURL.aspx";
  < /script >

Plain HTML(you can add following code between your <head> and </head> tags):


 < equiv="REFRESH" content="0;url=yourURL.aspx">

Difference between Response.redirect and Server.Transfer

noreply@blogger.com (prajeesh) — Thu, 09 Jul 2009 19:47:00 +0000

In ASP.net we are redirecting to a page using Response.Redirect("PageName.aspx") ; or
using Server.Transfer("PageName.aspx"); difference between these two commands are
Response.Redirect tells browser to redirect to another page where Server.Transfer instead of telling the browser it changes the focus of the web server to another page so it reduces HTTP requests and run your application faster also browser url will be same, please note that Server.Transfer can only used for redirection between the sites running in same server.
If you set PreserveForm parameter True then existing query strings and form values are available in next page too.

Asp.net Pay pal form posting problem

noreply@blogger.com (prajeesh) — Mon, 06 Jul 2009 20:29:00 +0000

Me and my colleague Anurag were trying to integrate a Paypal button in one of our recent project, we copied the button code available from Paypal website to our ASP.NET page and it was not worked and button click results only in a postback, at last we realized that it wont work as button code contained a form and ASP.net will not support more than one form in a page.
The button code we got from Paypal was like below:

We googled a lot to overcome this situation and finally we got a quick solution from Chyake Uchaya's blog, but the solution was not worked well in Mozilla, we done minor changes in the code and it worked perfectly finally, here is the code:

if you are not using Master pages, you can replace getElementById('aspnetForm') with getElementById('form1') or the form name you are using.

Windows 7 Upgrade option and pricing announced

noreply@blogger.com (prajeesh) — Sun, 05 Jul 2009 10:00:00 +0000

Microsoft corporation announces Windows 7 pricing and upgrade option program.
So here’s the low-down on pricing for Windows 7. The estimated retail prices for upgrade packaged retail product of Windows 7 in the U.S. are:
Windows 7 Home Premium (Upgrade): $119.99
Windows 7 Professional (Upgrade): $199.99
Windows 7 Ultimate (Upgrade): $219.99
And the estimated retail prices for full packaged retail product of Windows 7 in the U.S. are:
Windows 7 Home Premium (Full): $199.99
Windows 7 Professional (Full): $299.99
Windows 7 Ultimate (Full): $319.99
This means that Windows 7 Home Premium full retail product is $40.00 less than Windows Vista Home Premium today.

Read full story here

Image Resizing while uploading using asp.net

noreply@blogger.com (prajeesh) — Sun, 05 Jul 2009 07:52:00 +0000

Many asp.net communities and discussion forums are flooded with questions on how to resize images while uploading or how to generate image thumbnails while uploading an image, i have seen many posts giving the solution, here i am going to combine some solutions and created a simple solution.
Another feature of this solution is you can upload any number of images at a time.
Here is the code:



using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.IO;
/// 
/// Summary description for clsImageUpload : Credits : http://prajeeshkk.blogspot.com
/// 

public class clsImageUpload
{
string fileName;
public clsImageUpload()
{
//
// TODO: Add constructor logic here
//
}
//This function is called from aspnet page, it takes directory name as parameter
public string HandleUploadedFile(string directory)
{
// To get the root of the web site
string root = HttpContext.Current.Server.MapPath("~/");
// clean up the path
if (!root.EndsWith(@"\"))
root += @"\";
// make a folder to store the images in
string fileDirectory = root + @"\" + directory + "\\";
// create the folder if it does not exist
// make a link to the new file

// loop through the file in the request
for (int i = 0; i < HttpContext.Current.Request.Files.Count; i++)
{
// get the file instance
HttpPostedFile fi = HttpContext.Current.Request.Files.Get(i);
// create a byte array to store the file bytes
byte[] fileBytes = new byte[fi.ContentLength];
// fill the byte array
using (System.IO.Stream stream = fi.InputStream)
{
stream.Read(fileBytes, 0, fi.ContentLength);
}
// create a random file name
fileName = Guid.NewGuid().ToString();

// write the resized file to the file system
File.WriteAllBytes(fileDirectory + fileName + "_thumb.jpg", ResizeImageFile(fileBytes, 75));
fileBytes = null;
}
return (fileName + "_thumb.jpg");
}
public void HandleUploadedFileUseExistingName(string directory, string fname)
{
// get the root of the web site
string root = HttpContext.Current.Server.MapPath("~/");
// clean up the path
if (!root.EndsWith(@"\"))
root += @"\";
// make a folder to store the images in
string fileDirectory = root + @"\" + directory + "\\";
// loop through the file in the request
for (int i = 0; i < HttpContext.Current.Request.Files.Count; i++)
{
// get the file instance
HttpPostedFile fi = HttpContext.Current.Request.Files.Get(i);
// create a byte array to store the file bytes
byte[] fileBytes = new byte[fi.ContentLength];
// fill the byte array
using (System.IO.Stream stream = fi.InputStream)
{
stream.Read(fileBytes, 0, fi.ContentLength);
}
// create a random file name
fileName = fname;
// write the resized file to the file system
File.WriteAllBytes(fileDirectory + fileName, ResizeImageFile(fileBytes, 75));
fileBytes = null;
}
}
/// This fuction returns a Byte array containing the resized file
private static byte[] ResizeImageFile(byte[] imageFile, int targetSize)
{
using (System.Drawing.Image oldImage =
System.Drawing.Image.FromStream(new MemoryStream(imageFile)))
{
//If you want to maintain the propotion use following code
//Size newSize = CalculateDimensions(oldImage.Size, targetSize);
//If you want to use a fixed size use following one
Size newSize = GetDimension();
using (Bitmap newImage =
new Bitmap(newSize.Width,
newSize.Height, PixelFormat.Format24bppRgb))
{
using (Graphics canvas = Graphics.FromImage(newImage))
{
canvas.SmoothingMode = SmoothingMode.AntiAlias;
canvas.InterpolationMode = InterpolationMode.HighQualityBicubic;
canvas.PixelOffsetMode = PixelOffsetMode.HighQuality;
canvas.DrawImage(oldImage,
new Rectangle(new Point(0, 0), newSize));
MemoryStream m = new MemoryStream();
newImage.Save(m, ImageFormat.Jpeg);
return m.GetBuffer();
}
}
}
}
/// This function Calculates the new size of the image based on the target size
private static Size CalculateDimensions(Size oldSize, int targetSize)
{
Size newSize = new Size();
if (oldSize.Height > oldSize.Width)
{
newSize.Width =
(int)(oldSize.Width * ((float)targetSize / (float)oldSize.Height));
newSize.Height = targetSize;
}
else
{
newSize.Width = targetSize;
newSize.Height =
(int)(oldSize.Height * ((float)targetSize / (float)oldSize.Width));
}
return newSize;
}
//Dimension of the images can be set here
private static Size GetDimension()
{
Size newSize = new Size();
newSize.Width = 100;
newSize.Height = 100;
return newSize;
}
}

You can download source code from here

Convert data table to data reader

noreply@blogger.com (prajeesh) — Fri, 03 Jul 2009 17:09:00 +0000

In some situations you may need to convert your data table to data reader, suppose you have a Data table named dt and etDataFromDB() is a function that returns a data table, here is the steps to convert data table to data reader.
DataTable dt = new DataTable();
dt = getDataFromDB();
DataTableReader dtr;
dtr = dt.CreateDataReader();
while (dtr.Read())
{
//Do your tasks

}

Calling a server side function from Grid view

noreply@blogger.com (prajeesh) — Tue, 30 Jun 2009 12:23:00 +0000

Suppose you have a Grid view and you want to display values returned from a server side function that accepts a bound value rather displaying bounded values itself, then you have to add a template field in the Grid view and add following code.
<asp:TemplateField HeaderText="Status">
<ItemTemplate>
<%#YourFunction(Eval("Status"))%>
</ItemTemplate>
</asp:TemplateField>

Add auto number column in Gridview

noreply@blogger.com (prajeesh) — Sun, 28 Jun 2009 16:02:00 +0000

In many situations we may need to add auto number or serial numbers in grid view column, but we cannot find a property in property window to add this.
We can add auto number column in Grid view or Data List by using Container.DataItemIndex property in Gridview or Data List mark up.

Add a Template field and add following code in Grid view Mark up:

<asp:TemplateField HeaderText="Serial Number">
<ItemTemplate>
<%# Container.DataItemIndex + 1 %>
</ItemTemplate>
</asp:TemplateField>

Calling parameterized XML web service from javascript

noreply@blogger.com (prajeesh) — Sun, 28 Jun 2009 11:32:00 +0000

In a previous post i have explained about calling a web service from javascript, please see this post to see calling a web service without parameters.
Suppose you have a web service that accepts user name and password and returns a value in XML format and you want to show the returned value in a webpage or a widget.

For example :

<?xml version="1.0" encoding="utf-8" ?>
<int xmlns="http://tempuri.org/">1</int>

You can use following code snippet to call a web service from javascript:
<script language="text/javascript">
var returned_data;
var request = new XMLHttpRequest();
//function to initialize web service
function initializeWebservice()
{
var url="http://2test.hopto.org/Leadservice.asmx/GetLeadCounts?UserName=Prajeesh&Password=123456";; //Web service url
request.onreadystatechange = webStatusProc;
request.open( "GET", url, true );
request.send();
}
//function to process webservice response
function webStatusProc()
{
if (request.readyState == 4) // Request completed?
{
response = request.responseXML.toXML();
XML = XMLDOM.parse( response);
returned_data= XML.evaluate('string(/int)');
alert(returned-data);
//do anything with returned data
}
}
</script>

Google website speed analyzer Add-on released

noreply@blogger.com (prajeesh) — Fri, 05 Jun 2009 14:55:00 +0000

Google code released an open source web page speed analyzer for Mozilla, called "Page Speed" it works like yahoo Yslow.

Page Speed is an open-source Firefox/Firebug Add-on. Webmasters and web developers can use Page Speed to evaluate the performance of their web pages and to get suggestions on how to improve them.

You can download it from Here

Client side image upload validation in asp.net

noreply@blogger.com (prajeesh) — Tue, 02 Jun 2009 22:48:00 +0000

We can upload images very easily using File upload control in asp.net, also you can validate the upload the file type using Reguler expression validator, following is the regular expression validation control code for validating image types such as jpg, png and bmp.
<asp:RegularExpressionValidator ID="RegularExpressionValidator2" runat="server"
ErrorMessage="Upload a valid image (jpg/png/bmp)"
ValidationExpression ="^.+\.((jpg)(JPG)(gif)(GIF)(jpeg)(JPEG)(png)(PNG)(bmp)(BMP))$"
ControlToValidate="fupImage" ValidationGroup="Author_reg"> Upload a valid image;</asp:RegularExpressionValidator>

Calling a web service from javascript

noreply@blogger.com (prajeesh) — Fri, 15 May 2009 21:46:00 +0000

Suppose you have a web service that returns a value in XML format and you want to show the returned value in a webpage or a widget.
For example :

<?xml version="1.0" encoding="utf-8" ?>
<int xmlns="http://tempuri.org/">1</int>

You can use following code snippet to call a web service from javascript:
<script language="text/javascript">
var returned_data;
var request = new XMLHttpRequest();
//function to initialize web service
function initializeWebservice()
{
var url = http://Localhost/Testwebservice.asmx/GetLeadCounts; //Web service url
request.onreadystatechange = webStatusProc;
request.open( "GET", url, true );
request.send();
}
//function to process webservice response
function webStatusProc()
{
if (request.readyState == 4) // Request completed?
{
response = request.responseXML.toXML();
XML = XMLDOM.parse( response);
returned_data= XML.evaluate('string(/int)');
alert(returned-data);
//do anything with returned data
}
}
</script>

The test form is only available for requests from the local machine

noreply@blogger.com (prajeesh) — Fri, 15 May 2009 11:25:00 +0000

If you find "The test form is only available for requests from the local machine" message in your webservice page after hosted in your server, dont worry just add following tags in your web.config file just before </system.web>
tag
<webServices>
<protocols>
<add name="HttpGet"/>
<add name="HttpPost"/>
</protocols>
</webServices>

How to create visitors counter using ASP dot net

noreply@blogger.com (prajeesh) — Tue, 05 May 2009 07:22:00 +0000

In some sites you may have seen visitors counter/Total hits at the bottom of the website, in asp.net it is very easy to implement this feature, here i will show you a simple example that stores visitors count in a Text file.
First you have to add a Global.asax file into the solution you are working, you can do this by Right clicking your project name in the solution explorer ->Add New Item -> Global Application Class.
create a Hits.txt file in the root folder of your application and just add following code in the Session_Start event in the Global.asax file.

void Session_Start(object sender, EventArgs e)
{
// Code that runs when a new session is started
Application.Lock();
if (System.IO.File.Exists(Server.MapPath(Request.ApplicationPath + "/Hits.txt")))
{
System.IO.StreamReader sr = new System.IO.StreamReader(Server.MapPath(Request.ApplicationPath + "/Hits.txt"));
string count = sr.ReadToEnd();
sr.Dispose();
Application["Hits"] = int.Parse(count) + 1;
System.IO.StreamWriter sw = new System.IO.StreamWriter(Server.MapPath(Request.ApplicationPath + "/Hits.txt"));
sw.Write(Application["Hits"].ToString());
sw.Dispose();
}
//Application["Hits"] = int.Parse(Application["Hits"].ToString()) + 1;
Application["OnlineUsers"] = (int)Application["OnlineUsers"] + 1;
Application.UnLock();
}
Reading Data from Hits.text file:
if (System.IO.File.Exists(Server.MapPath(Request.ApplicationPath + "/TestFile.txt"))){
{
System.IO.StreamReader sr = new System.IO.StreamReader(Server.MapPath(Request.ApplicationPath + "/Hits.txt"));
string strdata = sr.ReadToEnd();
sr.Dispose();
}
Here total hits will be available in "strdata" variable.
we have to create a StreamReader object to read data from a text file, follow this MSDN article to know more about StreamReader class.