Question

In MVC2 I used to create strongly typed views in a way that when I posted, I never used the FormCollection object. My signatures always looked like so:

[AcceptVerbs(HttpVers.Post)] 
public Create(Person newPerson)
{ 
//code to update the person from the post
}

But now I’m seeing this new TryUpdateModel way where I would just write something like:

    [AcceptVerbs(HttpVers.Post)] 
    public Create()
    { 
        Person thePersonToCreate = new Person()
        TryUpdateModel(thePersonToCreate)
        {
            //Code to create the person if model is valid
        }    
    }

So now it seems I have to mock up the HTTPContext in order to test this method. However, it seems like I can still use the former way using strongly typed methods. I realize that the TryUpdateModel method is an improvement for those who would use the FormCollection method of doing things but why bother with TryUpdateModel?

Answer 1

There are instances where this is desirable. A good example is when your model requires a more complex initialization, or factory method to create.

[AcceptVerbs(HttpVers.Post)] 
public Create()
{ 
    var dataAccess = new MyDataAccess("Another Param");
    Person thePersonToCreate = new Person(dataAccess);

    TryUpdateModel(thePersonToCreate)
    {
        //Code to create the person if model is valid
    }    
}

Now one might argue that a custom ModelBinder is a better solution here, but that might be more effort than it is worth if this is a one off situation. Also, hiding this detail in a ModelBinder makes errors more difficult to debug.

There are other situations I’m sure, but this is just a quick example.