What is the point of the key parameter in ModelState.AddModelError in ASP.NET MVC?

Question

I\'ve added validation checks in my controller that modify the ModelState if the validation fails.

For example:

Answer 1

The Key is used by the ValidationMessage HTML Helper to know the exact error message to display.

Example:

<%=Html.TextBox("Name") %> 

<%=Html.ValidationMessage("Name") %>

the ValidationMessage helper will display the message that has the key "Name" in the ModelState dictionary.