Question

I am creating a User Control, and I want it to know nothing about my Database Class.

However, I need certain features from that Database Class (I need to get the Employee’s name given their Employee Number).

What I would like to do is to create something in my User Control that I can wire up in my applications that use it, much like I would wire up a Click Event or something like that.

I’ve never actually created something like this before in a C# project, so I don’t know what to call it. I would imagine it has to exist.

The function I want to call in my Database Class has this signature:

public string GetEmployeeName(int employeeNumber);

Could someone tell me what it is I am trying to do?

If it is something difficult, an example would be nice as well.

Answer 1

You can do this using a delegate e.g. Func<TArgument, TResult>;

Add a public field to your usercontrol:

//A method that has an int parameter and returns a string
public Func<int, string> GetEmployeeName;

In your user control when you need to get the employee name you can use the delegate:

string employeeName;
if (GetEmployeeName != null)
    employeeName = GetEmployeeName(employeeNumber);

You can set the delegate from the hosting page or control by doing:

myUserControl.GetEmployeeName = GetEmployeeName;