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Consequence of changing web.config at runtime

In this article I will show the consequence of changing web.config at runtime. This topic contains following sections

   1. Software Requirement

   2. Prerequisite Knowledge

   3. Steps of execution

   4. Create a new project

   5. Add controls on page

   6. Code

   7. Output

Software requirement

Before you start reading this tutorial you should make sure that Visual studio (any version) is installed on your machine.

Prerequisite knowledge

Before you go ahead, it is required that you should know

   1. How to create a project using visual studio?

   2. Basics about asp.net controls and their events.

   3. Basics about state objects like session, viewstate etc.

Steps of execution

In this tutorial I will execute certain steps for the demonstration of consequence of changing web.config at runtime. These steps are

1. Create a new project

2. Add controls on page

Let us execute each step

Create a new project

Create a new website (Web based project). See the screen shot below

Picture shows the sample asp.net project in visual studio

Click to Enlarge

Add controls on page

Add 3 buttons and one label on the page

   1. Label – To display the value of session variable on click of button with the caption ‘Get Session Value’

   2. Get session value button – When clicked get the value of session variable and display the value in the label.

   3. Change web.config button – Change the value of connection string with key ‘ApplicationServices’ in web.config file.

   4. Set session value button - Set the value of session variable to some hard coded value (4 in this current example).

To check the consequence of changing web.config at run time, first of all we will set the value of session variable by clicking on the button ‘Set session value’, then display the value in label by clicking on button ‘Get session value’.

Then change the web.config at run time by clicking on the button ‘Change web.config’. Finally get the value of session variable by clicking on ‘Get session value’. After doing this exercise you can see the result i.e. session variable resets when we change the value of web.config at run time.

Code

Aspx code

<asp:Button ID="Button1" runat="server" Text="Get session value"  OnClick="Button1_Click"/>
<asp:Button ID="Button2" runat="server" Text="Change web.config" OnClick="Button2_Click" />
<asp:Button ID="Button3" runat="server" Text="Set session value" OnClick="Button3_Click" />
<asp:Label ID="Label1" runat="server" Text=""></asp:Label>

Code behind

//Get session value
protected void Button1_Click(object sender, EventArgs e) {
  Label1.Text = "Current Session value is : " + Session["ID"];
}
//Change config value
protected void Button2_Click(object sender, EventArgs e) {
  Configuration conf = WebConfigurationManager.OpenWebConfiguration("~");
  conf.ConnectionStrings.ConnectionStrings["ApplicationServices"].ConnectionString = "Test1";
  conf.Save();
}
//set session value
protected void Button3_Click(object sender, EventArgs e) {
  Session["ID"] = 4;
}

Output

Picture displays the effect of changing the web.config file on session variable

Click to Enlarge

Posted By -	Karan Gupta

Posted On -	Tuesday, October 1, 2013

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