Raise custom events in C# WinForms

Question

I have some Events I created on my own and was wondering on how to raise them when I want.

Probably my application design is also messed up, might take a look at that if you like.

This is the Structure

ProgramContext
 - Form MainWindow
  + Control TextBox
  + Control Button
  + ...

In this case, the MainWindow.TextBox holds some information that is updated quite often at runtime. So, I somehow need it to refresh itself when I want to (so it can reload its data from the database, where the it's stored)

I tried hooking an EventHandler to its Validating-Event, but that didn't seem to do the trick.

So, basically I have a method that reloads the data in ProgramContext

DataTable table = _adapter.GetData();
foreach (DataRow row in table.Rows)
{
  MainWindow.TextBox.Text += table.Text.ToString();
}

That needs to be done whenever another method (that writes new data into table) is executed.

Any ideas?

Answer 1

Edit : It seems your question is more about hooking into a specific event, but FWIW below is how to fire custom events in general.

Handling the TextBox Changed Event

From what I understand, you want an external party to monitor events raised from a textbox on a Form and then to reload data on another form?

A quick and dirty would be to make the Form TextBox public and then others could subscribe to this event

MainForm.textBox1.TextChanged += new System.EventHandler(this.textBox1_TextChanged);

OR, in more recent versions of C#:

MainForm.textBox1.TextChanged += this.textBox1_TextChanged;

Adding Your own Custom Event

Another, cleaner way would be to raise a custom event, - e.g. MyDataChangedEvent below. This will allow you to abstract away the fact that the changes are coming from a textbox at all.

// Assuming you need a custom signature for your event. If not, use an existing standard event delegate
public delegate void myDataChangedDelegate(object sender, YourCustomArgsHere args);

// Expose the event off your component
public event myDataChangedDelegate MyDataChangedEvent;

// And to raise it
var eventSubscribers = MyDataChangedEvent;
if (eventSubscribers != null)
{
   eventSubscribers(this, myCustomArgsHere);
}

You might also look at the Ent Lib Composite Application Block and Smart Client Software Factory - this has a very flexible event broking / pub sub mechanism for synchronising across UI "SmartParts" (controls, forms dialogs etc) in a loose-coupled fashion. (CAB is now very dated).