Tag: asp.net mvc


ASP.NET MVC generates invalid ClientIDs

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This week I had a joy of spending several hours trying to solve and intermitently happening bug. In short, some 2 times out of 3 the YUI selector utility failed to lookup elements in an XHR loaded HTML fragment. After digging quite deep into the YUI code, I found that it was actually the fault of the way ASP.NET MVC treats partial views.


  • ASP.NET MVC allows use of ASCX as “partial views”
  • It correctly assumes, that uniqueness of ClientID should be preserved
  • It incorrectly does not prepend an alpha-character to automatically generated GUID based IDs
  • User agents and selector libraries may correctly ignore such invalid IDs
  • Solution: override ViewUserControl.UniqueID