Converting a Web Forms Page to a User Control

Artikel
10/17/2014

If you have developed a Web Forms page and decide you would like to access its functionality throughout your application, you can make some minor alterations to the file to change it to a user control. Since the <html>, <body>, and <form> elements are not included in user controls, you must include these elements in the containing Web Forms page.

CAUTION If you are developing a user control in a code-behind class, you must extend the UserControl class rather than the Page class. For more information, see Developing User Controls in a Code-Behind File.

To convert a Web Forms page into a user control

Remove all <html>, <body>, and <form> elements from the page. The following example illustrates this conversion.

Initial Web Forms page:

<html>
<script language="VB" runat=server>
Sub EnterBtn_Click(Sender as Object, E as EventArgs)
   Label1.Text = "Hi " & Name.Text & " welcome to ASP.NET!"
End Sub
</script>
<body>
<h3>Web Forms Page</h3>
<form>
    Enter Name: <asp:textbox id="Name" runat=server/>
    <asp:button Text="Enter" OnClick="EnterBtn_Click"
         runat=server/>
<br><br>
<asp:label id="Label1" runat=server/>
</form>
</body>
</html>

[C#]
<html>
<script language="C#" runat=server>
void EnterBtn_Click(Object Sender, EventArgs E){
   Label1.Text = "Hi " + Name.Text + " welcome to ASP.NET!";
}
</script>
<body>
<h3>Web Forms Page</h3>
<form>
    Enter Name: <asp:textbox id="Name" runat=server/>
        <asp:button Text="Enter" OnClick="EnterBtn_Click"
            runat=server/>
    <br><br>
    <asp:label id="Label1" runat=server/>
</form>
</body>
</html>

The user control, following the conversion:

<h3> <u>User Control</u> </h3>
<script language="VB" runat=server>
Sub EnterBtn_Click(Sender as Object, E as EventArgs)
    Label1.Text = "Hi " & Name.Text & " welcome to ASP.NET!"
End Sub
</script>
    Enter Name: <asp:textbox id="Name" runat=server/>
    <asp:button Text="Enter" OnClick="EnterBtn_Click"
        runat=server/>
    <br><br>
    <asp:label id="Label1" runat=server/>

[C#]
<h3>User Control</h3>
<script language="C#" runat=server>
void EnterBtn_Click(Object Sender, EventArgs E){
    Label1.Text = "Hi " + Name.Text + " welcome to ASP.NET!";
}
</script>
    Enter Name: <asp:textbox id="Name" runat=server/>
    <asp:button Text="Enter" OnClick="EnterBtn_Click"
        runat=server/>
    <br><br>
    <asp:label id="Label1" runat=server/>

If there is an @ Page directive in the Web Forms page, change it to an @ Control directive.

Note To avoid parser errors when you convert a page to a user control, remove any attributes supported by the @ Page directive that are not supported by the @ Control directive. For more information, see Directive Syntax.
Include a className attribute in the @ Control directive. This allows the user control to be strongly typed when it is added to a page or other server controls programmatically.
Give the control a file name that reflects how you plan to use it and change the file name extension from .aspx to .ascx.

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Converting a Web Forms Page to a User Control

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