Question

I have a gridview that is bound to the result from an nhibernate query. If the first item in the list is edited the following exception is thrown:

System.Reflection.TargetException: Object does not match target type

It appears that the problem is caused by the fact that databinding can’t deal with the first item in the list being a subtype of the other items in the list.

What is a nice / correct way to solve this problem? Currently I have had to turn off nhibernates proxying.

Edit: I have another couple of solutions:

• Clone everything in the list (http://steve-fair-dev.blogspot.com/2007/08/databind-object-does-not-match-target.html) – this doesn’t work for me as the object doesn’t implement ICloneable
• change the order of items in the list so that the proxy isn’t first (http://community.devexpress.com/forums/t/30797.aspx) – this is so hacky, I don’t think I can stoop this low!

But none of these feel right though…

Answer 1

Is the root cause due to a proxy object in the list (from lazy loading) or because the list isn’t homogeneous (contains multiple types even if they belong to the same class hierarchy)? The problem with non-homogeneous data sets is a known limitation. See this and this.

I don’t think there’s a solution other than to not use databinding to populate the grid. That’s easy enough if it’s read-only.