User-1912369449 posted
DataAnnotationsModelBinder works fine with ViewModels which are not made up of complex object hierarchies, such as
public
class Baz<o:p></o:p>
{<o:p></o:p>
[Required]<o:p></o:p>
public string Bar {
get; set; }<o:p></o:p>
}
However, DataAnnotationsModelBinder does not work with complex ViewModels such as this one:<o:p></o:p>
public class Foo
{
public Baz MyBaz { get; set;}
#region Nested type: Baz
public class Baz
{
[Required]
public string Bar { get; set; }
}
#endregion
}
If my view posts a value for Foo.Baz.Bar,
the DataAnnotationsModelBinder throws a NullReferenceException when trying to bind the model. This is a big problem for me since I really prefer using custom ViewModels instead of untyped ViewData arrays, so I often
end up putting Linq entites inside a wrapper class to create a custom ViewModel. <o:p></o:p>
The only workaround I have found so far is to expose the properties you need to post back from the view in the topmost hierarchy layer of the ViewModel:<o:p></o:p>
public
class Baz<o:p></o:p>
{<o:p></o:p>
[Required]<o:p></o:p>
public
string Bar { get;
set; }<o:p></o:p>
}<o:p></o:p>
<o:p> </o:p>
public
class ViewModel<o:p></o:p>
{<o:p></o:p>
private
Baz myBazInstance;<o:p></o:p>
<o:p></o:p>
[Required]<o:p></o:p>
public string ExposedBar<o:p></o:p>
{<o:p></o:p>
get { return MyBaz.Bar; }<o:p></o:p>
set { MyBaz.Bar =
value; }<o:p></o:p>
}<o:p></o:p>
<o:p> </o:p>
public
Baz MyBaz<o:p></o:p>
{<o:p></o:p>
get { return myBazInstance ?? (myBazInstance =
new Baz());}<o:p></o:p>
set { myBazInstance =
value; }<o:p></o:p>
}<o:p></o:p>
}<o:p></o:p>
But I don’t want to write this extra code for every single property in my linq entity.
Also, I really don’t want to repeatedly the ValidationAttributes I already typed in my Linq Entity as I did above. Has anyone else seen this problem and is there a better workaround?
