How to send a value from a LinkButton to the server?

Question

I have many LinkButton such as:

<asp:LinkButton runat="server" onclick="cmdCancellaComunicazione_Click">X</asp:LinkButton> 

they call the same server method, cmdCancellaComunicazione_Click. but I need to distinguish them (passing to the server, for example, a value).

How can I do it? I know there is CommandArgument, but I can't set to it a value such as <%= myValue %>

Answer 1

Your code has no ID specified on your LinkButton which seems odd.

You should be able to assign the CommandArgument server side with:

yourLinkButton.CommandArgument = yourValue;

And then it will be read it server side in your OnClick handler.

 protected void cmdCancellaComunicazione_Click(object sender, EventArgs e)
 {
     LinkButton btn = (LinkButton)sender;
     if (btn.CommandArgument.Equals(something here))
     {
          // do something
     }
     else
     {
          // do something else
     }
 }

Is this being created in a grid or something that is being bound? If so I would implement the OnDataBinding event for the LinkButton like:

<asp:LinkButton ID="yourLinkButton"
    runat="server" OnDataBinding="yourLinkButton_DataBinding"
    onclick="cmdCancellaComunicazione_Click">X</asp:LinkButton>

Server side code (I try to avoid inline code whenever possible):

protected void protected void lblID_DataBinding(object sender, System.EventArgs e)
{
    LinkButton btn = (LinkButton)sender;
    btn.CommandArgument = yourValue;
}

Is there something more to your scenario that you have not included in your question?

Answer 2

You can use the sender argument of the event-handler. Cast it to LinkButton:

protected void cmdCancellaComunicazione_Click(Object sender, EventArgs e) 
{
   LinkButton lbtn = (LinkButton) sender;
}

Then you can use it's CommandName, ID or Text to distinguish.

Answer 3

In your method, you can cast the sender to a LinkButton and inspect the value there.

Answer 4

OnCommand would be a good option here.

protected void ButtonCommand(object sender, CommandEventArgs e)
{
    string theCommand = e.CommandArgument.ToString();
}

Just add the OnCommand and CommandArgument to the LinkButton.

<asp:LinkButton id="LinkButton1" Text="The Text" OnCommand="ButtonCommand" CommandArgument="YourInfo" runat="server"></asp:LinkButton>