ConstraintException is thrown when posting empty data for non-nullable properties
Jul 5, 2010
I am working with model validation in .NET, Entity Framework 4,
partial classes with
MetadataType connections and now have a problem where exceptions
are thrown when posting empty data for non-nullable properties.
In my model, I have an
Employee entity for which some properties are non-nullable.
I also have a partial class and a metadata class, to be used with model validation,
as described in this blog post.
This approach works great.
Employee is validated properly, with minimum effort. My
entities are validated with standard validation attributes as well as a set of custom
However, the application crashes when I post empty text. A
thrown before any view controller actions are executed, which means that I can’t act
on the exception.
The exception occurs since the empty posted data causes the corresponding properties
Employee class to be set to
null, which conflicts with the non-null setup
in the entity model. However, since I have custom validation classes that use
Required attributes to make properties mandatory, I don’t need the non-nullable
attributes in my model.
As such, I can set the nullable property to (None) and the exception is now history!