当dto具有数据注释时，PutAsJsonAsync不起作用

Question

I'm seeing some strange behavior with HttpClient and Web API with my DTOs. When I have data annotations in place for my properties, HttpClient.PutAsJsonAsync() does not work. I can't receive anything at the Web API end. Some code to explain:

My MVC 4 web page calls the Web API with this code:

using (var client = new HttpClient())
{
    var response = client.PutAsJsonAsync(uri+"/"+MyObject.Id, MyObject).Result;
    response.EnsureSuccessStatusCode(); // Returns 500 when i use MyObject with annotations                             
}

Web API controller code to receive. Note that this is not even trigged when MyObject has annotations:

public MyObject Put(MyObject myObject)
{
        try
        {
            if (myObject == null) throw new NullReferenceException();
        }
        catch (Exception e)
        {
            throw new HttpResponseException(Request.CreateResponse(HttpStatusCode.BadRequest));
        }
}

MyObject DTO when it works:

public class MyObject
{
    public int Id { get; set; }
    public Nullable<int> AuditProgramId { get; set; }
    public string Title { get; set; }
    public System.DateTime StartDate { get; set; }
    public System.DateTime EndDate { get; set; }
 }

MyObject DTO when it doesn't work:

public class MyObject
{
    public int Id { get; set; }
    public Nullable<int> AuditProgramId { get; set; }
    [Required]
    public string Title { get; set; }
    [Required, DataType(DataType.Date)]
    public System.DateTime StartDate { get; set; }
    [Required, DataType(DataType.Date)]
    public System.DateTime EndDate { get; set; }
 }

Any ideas?

UPDATE 1

It works with these values without annotations, but fails with annotations:

var myObj = new MyObject {
    Id=4,
    Title="Test Title",
    StartDate=DateTime.Today,
    EndDate=DateTime.Today.AddDays(2)
};

Answer 1

I can repro your scenario, and the exception message actually provide a solution to this problem:

Property 'StartDate' on type 'MvcApplication.Model.MyObject' is invalid. Value-typed properties marked as [Required] must also be marked with [DataMember(IsRequired=true)] to be recognized as required. Consider attributing the declaring type with [DataContract] and the property with [DataMember(IsRequired=true)].

I have modified my MyObject class accordingly and I got your scenario to work.

[DataContract]
public class MyObject
{
    [DataMember]
    public int Id { get; set; }

    [DataMember]
    public Nullable<int> AuditProgramId { get; set; }

    [DataMember]
    [Required]
    public string Title { get; set; }

    [Required, DataType(DataType.Date)]
    [DataMember(IsRequired = true)]
    public System.DateTime StartDate { get; set; }

    [Required, DataType(DataType.Date)]
    [DataMember(IsRequired = true)]
    public System.DateTime EndDate { get; set; }
}

FYI, a bug relating to this scenario is recently fixed to make things simpler: Overly aggressive validation for applying [DataMember(IsRequired=true)] to required properties with value types