Question

I created a control where other developers can create an instance and use. There is a button click in the control. How do I allow developers to plug in their own code in a certain part of my control? I am not sure if or how exactly to use a delegate or event in this scenario. Can someone help in the below example:

public class MyControl : CompositeControl
{
   ...
   void btnSubmit_Click(object sender, EventArgs e)
   {
      //DO SOMETHING
      if (success)
      {
         //CALL DEVELOPER'S LOGIC
      }
   }
}

In the developers code, how can they pass in their logic when the button click of the control is successful?

protected override void CreateChildControls()
{
    var ctlMyControl = new MyControl();

    //ADD SuccessCode() TO ctlMyControl
    //SO IT IS TRIGGERED ON SUCCESS
    //MAYBE SOMETHING LIKE:
    //ctlMyControl.SuccessEvent = SuccessCode()??

    this.Control.Add(ctlMyControl);
}

protected void SuccessCode()
{
    //DO SOMETHING
}

How to I update MyControl to allow this?

Answer 1

You need to add an event to the control, like this:

void btnSubmit_Click(object sender, EventArgs e) {
    //DO SOMETHING
    if (success) {
        OnSomethingCompleted();
    }
}

///<summary>Occurs when the operation is successfully completed.</summary>
public event EventHandler SomethingCompleted;
///<summary>Raises the SomethingCompleted event.</summary>
internal protected virtual void OnSomethingCompleted() { OnSomethingCompleted(EventArgs.Empty); }
///<summary>Raises the SomethingCompleted event.</summary>
///<param name="e">An EventArgs object that provides the event data.</param>
internal protected virtual void OnSomethingCompleted(EventArgs e) {
    if (SomethingCompleted != null)
        SomethingCompleted(this, e);
}

In the form, you can add a handler to the event, like this:

myControl.SomethingCompleted += myControl_SomethingCompleted;

void myControl_SomethingCompleted(object sender, EventArgs e) {
    //Do things
}

For more information, see the documentation.