Question

I have a ASP.NET 1.1 application, and I’m trying to find out why when I change a ComboBox which value is used to fill another one (parent-child relation), two postbacks are produced.

I have checked and checked the code, and I can’t find the cause.

Here are both call stacks which end in a page_load

First postback (generated by teh ComboBox’s autopostback)

Postback call stack (broken)

Second postback (this is what I want to find why it’s happening)

alt text (broken)

Any suggestion? What can I check?

Answer 1

It’s a very specific problem with this code, I doubt it will be useful for someone else, but here it goes:

A check was added to the combo’s onchange with an if, if the condition was met, an explicit call to the postback function was made. If the combo was set to AutoPostback, asp.net added the postback call again, producing the two postbacks…

The generated html was like this:

[select onchange='javascript: if (CustomFunction()){__doPostBack('name','')}; __doPostBack('name','')']