15

When I run the following sample it is throwing the following exception...

Additional information: The entity 'TestEntity' does not have a key defined.

I have configured the key using code first entity context... modelBuilder.Entity<TestEntity>().HasKey(t => t.EntityID);

What is the issue? why is OData V4 not using the configured key?

namespace WebApplication2
{
    public static class WebApiConfig
    {
        public static void Register(HttpConfiguration config)
        {
            // Web API configuration and services

            // Web API routes
            config.MapHttpAttributeRoutes();

            config.Routes.MapHttpRoute(
                name: "DefaultApi",
                routeTemplate: "api/{controller}/{id}",
                defaults: new { id = RouteParameter.Optional }
            );

            config.MapODataServiceRoute("odata", "odata", model: GetEDMModel());

        }

        private static IEdmModel GetEDMModel()
        {
            ODataModelBuilder builder = new ODataConventionModelBuilder();
            builder.EntitySet<TestEntity>("TestEntities");             
            return builder.GetEdmModel();
        }
    }


    public class TestEntity
    {
        public int EntityID { get; set; }
        public string Name { get; set; }
    }

    public partial class TestContext1 : DbContext
    {

        public TestContext1() : base("DB")
        {
        }
        public DbSet<TestEntity> Entities { get; set; }        
        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            modelBuilder.Entity<TestEntity>().HasKey(t => t.EntityID);

        }
    }

}
Peter Bons
  • 26,826
  • 4
  • 50
  • 74
Hanu
  • 173
  • 1
  • 2
  • 5

3 Answers3

35

You defined the key for the database mapping of Entity Framework but not for the OData mapping.

Try this:

 private static IEdmModel GetEDMModel()
 {
       ODataModelBuilder builder = new ODataConventionModelBuilder();
       var entitySet = builder.EntitySet<TestEntity>("TestEntities");
       entitySet.EntityType.HasKey(entity => entity.EntityID)
       return builder.GetEdmModel();
 }

Or try adding a [Key] Attribute to your TestEntity to tell OData (and Entity Framework at the same time) what Property is the key.

Like so:

using System.ComponentModel.DataAnnotations;

public class TestEntity
{
    [Key]
    public int EntityID { get; set; }
    public string Name { get; set; }
}
woelliJ
  • 1,494
  • 9
  • 17
  • 1
    In the Code first context already I mapped/configured the key. why we have to configure one more time. Moreover, same code works with OData v3 version "Microsoft.AspNet.WebApi.OData" but this is not working with "Microsoft.AspNet.OData" – Hanu Jun 05 '17 at 14:52
  • The one you configured is for Entity Framework mapping. Possibly OData requires a different mapping. You might also be able to circumvent this by adding a `[Key]` attribute above the EntityID property – woelliJ Jun 05 '17 at 14:53
  • 1
    modelBuilder.Entity().HasKey(t => t.EntityID) is nothing but [Key] attribute. But why it is working with [Key] attribute. Moreover this is supported feature in previous version. – Hanu Jun 05 '17 at 15:05
  • Possible OData is checking the [Key] attribute once you define the entity on the `ODataModelBuilder`. So when the attribute is not defined you'd have to tell the OData Model otherwise what to use as the Key for the entity. OData doesn't know about Entity Framework (you could put anything else as a data provider behind OData). And i'm just assuming. I'm afraid you'd have to verify it yourself. – woelliJ Jun 05 '17 at 17:46
  • @woelliJ your first suggestion - adding the HasKey - worked for me. Thanks! – ih303 Apr 16 '18 at 15:42
10

I came here from google and ran into this error, here is an example of what my class looked like

public class TestEntity
{
    [Key]
    public int EntityID { get; }//<-- missing set
    public string Name { get; set; }
}

only after I added the set to my [key] property did it get resolved. Here is the end result

public class TestEntity
{
    [Key]
    public int EntityID { get; set; }//<--- added set
    public string Name { get; set; }
}
Ben Anderson
  • 7,003
  • 4
  • 40
  • 40
0

if the class name is TestEntity and the id field is EntityID this is the problem change the class name to Entity or the field name to Id or TestEntityId this worked for me ,you can check this link for more solutions if this wasn't the case.

GH.Ezzat
  • 21
  • 7