CODEWITHSUNDEEP
c#asp.net-mvcentity-framework
bdparrish
bdparrish

Reputation: 2764

MVC 4 Beta - You must write an attribute 'type'='object' after writing the attribute with local name '__type'

I am working with the WebAPI in the new MVC 4 Beta. I came across this error when trying to get an entity that has a virtual ICollection<> property to populate. Is there a way to get around this as of right now? I understand this is in the Beta stage, so this might be fixed down the road. It was just a curiosity if there is a solution out there for this.

Upvotes: 6

Views: 2168

Answers (4)

Matthew
Matthew

Reputation: 411

Ran into this problem also. My situation was a little different though.

I had this structure and it would not work for me.

[DataContract]
public class MJPEGCamera : Camera
{
}
[DataContract]
public class H264Camera : Camera
{     
}
[DataContract]
public class Camera
{
    [DataMember]
    public string cameraName { get; set; }
    [DataMember]
    public string address { get; set; }
    [DataMember]
    public string format { get; set; }
    [DataMember]
    public string archiveDaysUrl { get; private set; }
    [DataMember]
    public string archiveHoursUrl { get; private set; }
}

So I just created a factory in camera to accomplish what I needed. Hope this will help somebody who finds this answer.

Upvotes: 0

Hero
Hero

Reputation: 1433

I had the same problem, it seems to be a problem with the default WebApi serializer. I added Json.Net as a formatter in my Global.asax.cs and it worked fine for me. I just followed this example: http://blogs.msdn.com/b/henrikn/archive/2012/02/18/using-json-net-with-asp-net-web-api.aspx

This is what I've got in my Global.asax.cs 

JsonSerializerSettings serializerSettings = new JsonSerializerSettings();
serializerSettings.Converters.Add(new IsoDateTimeConverter());
GlobalConfiguration.Configuration.Formatters[0] = new JsonNetFormatter(serializerSettings);

I just added the Json.Net package using NuGet and created the JsonNetFormatter class as explained in the post above.

Upvotes: 1

grahamesd
grahamesd

Reputation: 4993

I had a similar problem. I fixed it by using a sort of ViewModel class that only had simple types. I translated the object returned by the DbContext into my ViewModel class and passed that back to the client.

This wouldn't work in all situations, but it did in mine.

Upvotes: 0

bdparrish
bdparrish

Reputation: 2764

I got this to work by removing the virtual keyword and making sure that the objects and collections that did have a virtual keyword were provided in the Include statement within my repository.

public class Order
{
    public int ID { get; set; }
    public DateTime OrderDate { get; set; }
    public ICollection<Product> Products { get; set; }
}

public interface IOrderRepository
{
    IQueryable<Order> Orders { get; }
    void SaveOrder(Order order);
    void DeleteOrder(Order order);
}

public class OrderRepository
{
    StoreDbContext db = new StoreDbContext();

    public IQueryable<Order> Orders
    {
        get { return db.Orders.Include("Products"); }
    }

    public void SaveOrder(Order order)
    {
        db.Entry(order).State = order.ID == 0 ? 
                EntityState.Added : 
                EntityState.Modified;

        db.SaveChanges();
    }

    public void DeleteOrder(Order order)
    {
        db.Orders.Remove(order);

        db.SaveChanges();
    }
}

Upvotes: 2

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