QueryString in ASP.NET

This blog explains -
  • What is QueryString?
  • Why do we use QueryString?
  • How to pass the values through QueryString?
  • How to retrieve the values from QueryString?
  • Query string is one of the technique to send data from one webform to another through URL.
  • Query string consist of two parts (field and value), and each of pair separated by ampersand (&).
  • ?(Question Mark), indicates the beginning of a query string and it's value.
  • There is a limit on the Query string length. Hence, Query strings cannot be used to send very long data.
  • Query strings are visible to the user, hence should not be used to send sensitive information (Like Username, Password), unless encrypted.
  • To retrieve the query string value, use Request object's QueryString property.
Lets understand with an example: 
  • To create the project -
  • Go to Start -> then All Programs and click Microsoft Visual Studio 2010
  • Go to File -> New -> Project..., Visual C# , Web. Then select ASP.NET Empty Web Application.
  • Provide the project a name and specify the location. 
Next: Right-click on Solution Explorer and add a two web forms (user.aspx, Mas_Employee.aspx) to your project.
Send the Values using QueryString :
Design your user.aspx as in the following.
Copythe following code in your button click event to send multiple query string values (Name, DeptNmae) through URL from user.aspxpage to Mas_Employee.aspx.
  1. protected void btnSend_Click(object sender, EventArgs e)  
  2. {  
  3.    Response.Redirect("/Application /Mas_Employee.aspx?Name=" + txtName.Text + "&DeptName=" + txtDeptName.Text);  
  4. }  
 Retrieve the values from QueryString:
Design your Mas_Employee.aspx as in the following
To retrieve the QueryString Values (Name, DeptNmae) in Mas_Employee.aspx copy the following code in your Mas_Employee.aspx.cs.
  1. protected void Page_Load(object sender, EventArgs e)  
  2. {  
  3.    if (!IsPostBack)  
  4.    {  
  5.       if (Request.QueryString["Name"] != null && Request.QueryString["Name"] != string.Empty)  
  6.          lblName.Text = Request.QueryString["Name"];  
  8.       if (Request.QueryString["DeptName"] != null && Request.QueryString["Name"] != string.Empty)  
  9.          lblDeptName.Text = Request.QueryString["DeptName"];  
  10.    }  
  11. }  
Run the application and Provide Name and DeptName values and then click on Send. At this point you will get the following result.

QueryString are used to pass the data (limited data through URL) from one page to another page . For example. If we want to send one page control values to another page you can use QueryString.
I hope you enjoyed it. Please provide your valuable suggestions and feedback if you found this blog helpful.

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