Revalidating a modified ViewModel within a controller method?

Question

EDIT - We\'re using MVC4 Dev Preview....

I\'m implementing an edit page for a FishingTrip class. FishingTrip contains a c

Answer 1

Once you have removed the offending item(s), clear the ModelState and validate again, like so:

ModelState.Clear();
TryValidateModel(crew);  // assumes the model being passed is named "crew"

Note: Be carefull when use TryValidateModel method because this method does not validate nested object of model (As mentioned by @Merenzo).

Answer 2

Late to the game, but still: I was also looking for a way to validate model after doing some tweaks to it (more precisely - to the items of its nested collection) - and TryValidateModel didn't work for me, as it doesn't process nested objects.

Finally, I settled with custom model binder:

public class MyItemModelBinder : DefaultModelBinder
{
    protected override void OnModelUpdated(
        ControllerContext controllerContext, 
        ModelBindingContext bindingContext)
    {
        if (bindingContext.ModelType == typeof(MyItemModel))
        {
            MyItemModel item = (MyItemModel)bindingContext.Model;
            //do required tweaks on model here 
            //(I needed to load some additional data from DB)
        }
        //validation code will be called here, in OnModelUpdated implementation
        base.OnModelUpdated(controllerContext, bindingContext);
    }
}

on the model class:

[ModelBinder(typeof(MyItemModelBinder))]
public class MyItemModel : IValidatableObject
{
    //...
}