Question

Problem: I have an asp.net Textbox that I am putting text into and on text change it should assign its value to a variable, this does not happens.

Question: What is the best method to retrieve the value from the Textbox?

C# Code:

protected void btnSourceConnect_Click(object sender, EventArgs e)
{
    if (Util.Connection(SourceString, 0))
    {
        lblTesting.Text = "Working!";
    }
    else
    {
        lblTesting.Text = "It No Work";
    }
}
protected void txtSourceServer_TextChanged(object sender, EventArgs e)
{
        SourceString.DataSource = txtSourceServer.Text;      
}

protected void txtSourceDatabase_TextChanged(object sender, EventArgs e)
{

        SourceString.InitialCatalog = txtSourceDatabase.Text;

}

protected void txtSourceUN_TextChanged(object sender, EventArgs e)
{

        SourceString.UserID = txtSourceUN.Text;

}

protected void txtSourcePass_TextChanged(object sender, EventArgs e)
{

        SourceString.Password = txtSourcePass.Text;   
}

Asp.Net Code:

<table style="width: 100%;Border:1px solid Black;">
    <tr>
            <td class="style1">
                &nbsp;
                Source Server:</td>
            <td class="style1">
                &nbsp;&nbsp;
                <asp:TextBox ID="txtSourceServer" runat="server" 
                    ontextchanged="txtSourceServer_TextChanged" AutoPostBack="True"></asp:TextBox>
            </td>
            <td class="style1">
                &nbsp; Source Database:
            </td>
            <td class="style1">
                &nbsp;&nbsp;
                <asp:TextBox ID="txtSourceDatabase" runat="server" 
                    ontextchanged="txtSourceDatabase_TextChanged" AutoPostBack="True"></asp:TextBox>
            </td>

        </tr>
        <tr>
            <td class="style1">
                &nbsp; User Name:
            </td>
            <td class="style1">
                &nbsp;&nbsp;
                <asp:TextBox ID="txtSourceUN" runat="server" 
                    ontextchanged="txtSourceUN_TextChanged" AutoPostBack="True"></asp:TextBox>
            </td>
            <td class="style1">
                &nbsp; Password:
            </td>
            <td class="style1">
                &nbsp;&nbsp;
                <asp:TextBox ID="txtSourcePass" runat="server" 
                    ontextchanged="txtSourcePass_TextChanged" AutoPostBack="True"></asp:TextBox>
            </td>
        </tr>
        <tr>
            <td class="style1">
                &nbsp;
            </td>
            <td class="style1">
                &nbsp;
            </td>
            <td class="style1">
                &nbsp;
            </td>
            <td class="style1">
                &nbsp;
                <asp:Button ID="btnSourceConnect" runat="server" Text="Test Connection" 
                    onclick="btnSourceConnect_Click" />
            </td>
        </tr>
        </table>

Answer 1

What is the best method to retrieve the value from the Textbox?

The best method is like this control I am writing right now, you have a button that make post back, and then you read the value of the text box on code behind – on post back.

Using the AutoPostBack="True" on every TextBox you use involves too many unnecessary post backs to the server, it is better to use a “submit” button and save all your values when the user click on submit.

In you case you have a button, and you only need to remove the auto post back and set your values only when you try to connect as:

protected void btnSourceConnect_Click(object sender, EventArgs e)
{
    SourceString.UserID = txtSourceUN.Text;
    SourceString.DataSource = txtSourceServer.Text;      
    SourceString.InitialCatalog = txtSourceDatabase.Text;
    SourceString.Password = txtSourcePass.Text;   

    if (Util.Connection(SourceString, 0))
    {
        lblTesting.Text = "Working!";
    }
    else
    {
        lblTesting.Text = "It No Work";
    }
}