How to handle textbox's load event

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I have a form with lots of custom-made TextBoxes (let's call them InheritedTextBox). Now I need to set the MaxLength property based on the textbox's data binded property. The property itself has a MaxLength attribute that I need to read (that's trivial).

The problem is that the TextBox control doesn't have a Load event. So where should I call the code that sets the MaxLength property when the form is loaded? I've tried the textbox's constructor (no databindings set yet) and the TextBox.DataBindings.CollectionChanged event (doesn't get called until the textbox is disposed).

So in a nutshell:
- I bind a textbox into a datasource in designer (for example an Order entity and its property OrderID)
- The OrderID property has custom attribute MaxLength(30)
- I want that attribute's value to be set on the bound textbox's MaxLength when the form loads up

The binding don't exist when the textbox is being instantiated and there's no Load event. So what to do?

Any suggestions?

Posted 11-Aug-11 23:42pm

kornakar

Updated 12-Aug-11 2:17am

v3

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2 solutions

Solution 3

There is no such event; there is no a concept of loading of the text box. There is a read-only property System.Windows.Forms.TextBox.Text. The setter of this property fires the event System.Windows.Forms.TextBox.TextChanged. Use it — this is what you need.

—SA

Posted 13-Aug-11 20:02pm

Sergey Alexandrovich Kryukov

Comments

Abhinav S 14-Aug-11 2:05am

Fair enough. My 5.

Sergey Alexandrovich Kryukov 14-Aug-11 2:11am

Thank you, Abhinav.
--SA

kornakar 15-Aug-11 1:53am

I don't understand what I should do with TextChanged. I only wanted to set the MaxLength property once the form is loaded (not every time the text changes).

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#realJSOP · Accepted Answer · 2011-08-12T02:25:00

Solution 1

The Form has a Loaded event. You can use that handler and enumerate through the controls and if you find a textbox, do whatever you need to do.

Posted 12-Aug-11 2:25am

#realJSOP

Comments

kornakar 12-Aug-11 8:59am

So this is impossible to do inside the control? I have no choice but to create a base form and move the logic there?

Sergey Alexandrovich Kryukov 14-Aug-11 2:15am

It is possible, but the concept is different -- please see my answer.
--SA

Sergey Alexandrovich Kryukov 14-Aug-11 2:14am

John, I like you answer about Schrodinger's Cat paradox!
As to this one, I'm just not sure this is what OP needs. In fact Form.Loaded event is fictional. It is simply called from its constructor. OP mentioned "text box loaded"; I assumed TextBox.TextChanged is what should work -- please see my answer.
--SA

kornakar 15-Aug-11 1:53am

This seems the most appropriate solution. Thanks.