Question

Several times throughout the course of our current project, the visual studio designer has made modifications that resulted in losing code. For example, event handlers wirings that were set up manually in the designer code were lost. Does anyone know why this happens?

Edit: I understand that editing these files manually is not a good idea, but it has also happened with other event wirings set up through the designer.

Answer 1

Well for starters read the XML at the top of your designer.cs file.

/// <summary>
/// Required method for Designer support - do not modify
/// contents of this method with the code editor.
/// </summary>
private void InitializeComponent()

Generally you shouldn’t be modifying these files as they are auto-generated. It’s probably the reason why there is a slight attempt to hide the code within a branch, underneath the main partial class.

I have on occasion found that the process has removed its own auto-generated code that I’ve had to merge back in. Most commonly it decides it’s not going to instantiate custom user controls anymore, so when I start running I get a NullReferenceException.

Really the answer is to put the code somewhere else, like in the constructor before calling the InitializeComponent() method. If fellow developers aren’t aware of this, then you should inform them and educate them, the fact that the files are .designer.cs should raise questions even to newer developers as to why the strange extension.