Web APi OData V4 Issue "The entity '' does not have a key defined
Solution 1
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; }
}
Solution 2
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; }
}
![Hanu](https://lh4.googleusercontent.com/-5JYIAltBCXA/AAAAAAAAAAI/AAAAAAAAJeQ/y4GGCHN7luM/photo.jpg?sz=256)
Hanu
Updated on June 18, 2022Comments
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Hanu about 2 years
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); } } }
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Hanu about 7 yearsIn 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"
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woelliJ about 7 yearsThe 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 -
Hanu about 7 yearsmodelBuilder.Entity<TestEntity>().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.
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woelliJ about 7 yearsPossible 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. -
ih303 about 6 years@woelliJ your first suggestion - adding the HasKey - worked for me. Thanks!
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TheSoftwareJedi almost 5 yearsSame here although my setter was set to internal as it was auto-generated by the IDE. I changed to public.
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BrainSlugs83 over 3 yearsThis seems specific to Entity Framework, not OData.