Required properties in custom and web user controls

Question

User251781917 posted

How can I make a property in a custom control or web user control required, so that if that property is not set by the developer when using the control in a page, a compilation error occurs?

Thanks! 

Answer 1

User-16411453 posted

 Why not just check if the property exist, and if not, write to the screen, you must set the property

 

 

If [CssClass] Is string.Empty Then

writer.Write("Set the Css")

Exit 

End If 

 

 

Answer 2

User251781917 posted

Because I don't want to have to wait until run-time to figure out something was not configured properly. 

Answer 3

User1872602287 posted

Aggiekevin,

 You can use a preprocessor directive to trigger a compile-time error when a value is not defined for the property of the control.

private string myProperty; 

public string MyProperty

{

get

{

return this.myProperty;

}

set

{

this.myProperty = value;

}

In this case, I overrode the RenderContents method of the control and added a check of the property. This example will generate an error if you compile a page with the control if the value of the property (in this case a string) is null/empty:

protected override void RenderContents(HtmlTextWriter writer)

{

(other code to render the control's output here)...

if (string.IsNullOrEmpty(this.MyProperty))

{

#error - You must define a value for the MyProperty property!

}

}

 

Hope this helps!

 Jon