区分ASP.NET MVC4中的null和missing参数

Question

I'm writing an API. I want to allow a PUT method to update a resource. Below is an example model object representing the resource-

var resourceToUpdate = new TestResourceModel() 
    {
        Id = 5
        Name = "testName",
        Description = "description",
        etc...
    }

I want a client to be able to PUT to /TestResource/5 to update properties on the resource

Now, say that the client only wants to update property Name, but not description so sends the following request:

Name="testNewName"

In this case, the resource should be updated so Name is now "testNewName", put Description is still "description"

How do I distinguish this case (in my Controller method), from the case where the client wants to set the Description property to null:

Name="testNewName"
Description=

as my controller method will look like:

[HttpPut]
public ActionResult Index(TestResourceModel model)
{
    //True in both cases
    bool descriptionSet = model.Description == null;

Answer 1

Well you have to compare the incoming values with the values you want to update.. I mean null is null is null :) Alt. set an update flag in your model (bool isUpdate) then only change the values that isn't null.