Creating default Submit button in ASP.Net 2.0

By:
Harish Ranga, Microsoft MVP

One
of the most annoying things in developing web pages is handling the "Enter
key" for form submission. Enter key has been the favourite way users like
to submit forms. Though we provide Buttons to click on, the easiest and
intuitive way is that, I can enter some text, make some changes and then hit
"Enter" to accomplish my submission.



"Enter" Key is handled in a little tricky way by uplevel browsers like
Internet Explorer, when it comes to ASP.NET.

• 
  
  If there is a single Textbox and single button, then it becomes straight
  forward, the button is submitted. However, the event code doesnt get
  executed, though the page postsback.

• If
  there are two or more, buttons, then it takes up the first button as the
  default button. However, it still doesnt execute the event handler but just
  refreshes the page.

You
can supress the Enter key event using Javascript. But this would result in other
undesirable effects like, any Enter key in the form i.e. within Text Area or
basically where large text is entered, would be disabled.

The
earlier work around was to associate a javascript function to each Button to
verify the that the relevant button is submitted upon Enter key.

ASP.NET
2.0 introduces a wonderful work around for this. By simply specifying the "defaultbutton"
property to the ID of the , whose event you want to fire, your
job is done.

The
defaultbutton property can be specified at the Form level in
the form tag as well as at panel level in the definition tag.
The form level setting is overridden when specified at the panel level, for
those controls that are inside the panel.

Also,
the Event Handler for the specified button, fires thereby simulating a true
submit button functionality.

The
following sample code contains a form and 4 panels with each of them containing
different buttons. It can be noticed that for each panel, there is a default
button specified which would trigger the corresponding button's event handler
when "Enter" Key is pressed upon a text changed event.

id="form1" runat="server" defaultbutton="btn1">

ID="txt" runat="server">

ID="Button5" runat="server" Text="Cancel" OnClick="Button5_Click"
/>

ID="btn1" runat="server" Text="Submit" OnClick="btn1_Click"
/>

ID="pnl1" runat="server" defaultbutton="Button1">

ID="TextBox1" runat="server">

ID="TextBox2" runat="server">

ID="Button1" runat="server" Text="Button1" OnClick="Button1_Click"
/>

ID="Panel1" runat="server" defaultbutton="Button2">

ID="TextBox3" runat="server">

ID="TextBox4" runat="server">

ID="Button2" runat="server" Text="Button2" OnClick="Button2_Click"
/>

defaultbutton="Button3">

ID="TextBox5" runat="server">

ID="TextBox6" runat="server">

ID="Button3" runat="server" Text="Button3" OnClick="Button3_Click"
/>

ID="Panel3" runat="server" defaultbutton="Button4">

ID="TextBox7" runat="server">

ID="TextBox8" runat="server">

ID="Button4" runat="server" Text="Button4" OnClick="Button4_Click"
/>

The
corresponding, sample events for the button clicks are

protected
void Button1_Click(object sender, EventArgs e)

{

Response.Write(Button1.Text);

}

protected
void Button2_Click(object sender, EventArgs e)

{

Response.Write(Button2.Text);

}

protected
void Button3_Click(object sender, EventArgs e)

{

Response.Write(Button3.Text);

}

protected
void Button4_Click(object sender, EventArgs e)

{

Response.Write(Button4.Text);

}

protected
void btn1_Click(object sender, EventArgs e)

{

Response.Write(btn1.Text);

}

protected
void Button5_Click(object sender, EventArgs e)

{

Response.Write(Button5.Text);

}

Once
we execute the above functionality, we can notice, the corresponding Buttons'
text are displayed when the Enter key is pressed from within a panel and at the
form level, it fires the btn1
Button's
event.

This
would be a very useful feature in scenarios where we have different sections of
the page and would like to have Enter key fire corresponding submit button
events.