"The entity type 'CustomAttributeData' requires a primary key to be defined" error when I add-migration in EF Core

I put my models in a class library with Core. I already did the first migration to test a part of my model, but after a big enhancement, I deleted my database and migration to have only one V1 migration.

The thing is, after this deletion, when I try to add-migration I get this error:

System.InvalidOperationException: The entity type 'CustomAttributeData' requires a primary key to be defined.
   at Microsoft.EntityFrameworkCore.Internal.ModelValidator.ShowError(String message)
   at Microsoft.EntityFrameworkCore.Internal.ModelValidator.Validate(IModel model)
   at Microsoft.EntityFrameworkCore.Internal.RelationalModelValidator.Validate(IModel model)
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelSource.CreateModel(DbContext context, IConventionSetBuilder conventionSetBuilder, IModelValidator validator)
   at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory)
   at Microsoft.EntityFrameworkCore.Internal.DbContextServices.CreateModel()
   at Microsoft.EntityFrameworkCore.Internal.LazyRef`1.get_Value()
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitScoped(ScopedCallSite scopedCallSite, ServiceProvider provider)
   at Microsoft.Extensions.DependencyInjection.ServiceProvider.<>c__DisplayClass16_0.<RealizeService>b__0(ServiceProvider provider)
   at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetService[T](IServiceProvider provider)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitTransient(TransientCallSite transientCallSite, ServiceProvider provider)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitConstructor(ConstructorCallSite constructorCallSite, ServiceProvider provider)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitTransient(TransientCallSite transientCallSite, ServiceProvider provider)
   at Microsoft.Extensions.DependencyInjection.ServiceProvider.<>c__DisplayClass16_0.<RealizeService>b__0(ServiceProvider provider)
   at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService(IServiceProvider provider, Type serviceType)
   at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService[T](IServiceProvider provider)
   at Microsoft.EntityFrameworkCore.Design.Internal.MigrationsOperations.AddMigration(String name, String outputDir, String contextType)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigrationImpl(String name, String outputDir, String contextType)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.<>c__DisplayClass3_0`1.<Execute>b__0()
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)
The entity type 'CustomAttributeData' requires a primary key to be defined.

I don't know why I am getting this error. All my models have a primary key defined with DataAnnotation.

If needed, I can provide the new models.

Here's the context if is related/helpful:

public class AmcContext : DbContext
{
    public DbSet<User> Users { get; set; }
    public DbSet<Location> Location { get; set; }
    public DbSet<Rating> Rating { get; set; }
    public DbSet<RatingType> RatingType { get; set; }
    public DbSet<Subscription> Subscription { get; set; }
    public DbSet<Module> Module { get; set; }

    public AmcContext(): base()
    {

    }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Ignore<User>();
        modelBuilder.Entity<Client>().ToTable("Client");
        modelBuilder.Entity<Professionnal>().ToTable("Professional");

        base.OnModelCreating(modelBuilder);
    }

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        optionsBuilder.UseSqlServer(@"Server=localhost\SQLEXPRESS;Database=Askmycar;Trusted_Connection=True;");

        base.OnConfiguring(optionsBuilder);
    }
}

Thanks.

On one of my model I have a property like that :

public Type AvailableFor { get; set; } 

Type is an object so it was waiting for a primary key I change it to :

public string AvailableFor { get; set; } 

and its works.

Thanks to @H.Herzi :)

I actually wanted to use Type in my model, and I had already initialized the properties with a converter:

modelBuilder.Entity<...>()
    .Property(x => x.Type)
    .IsRequired()
    .HasConversion(
        convertToProviderExpression: x => x.AssemblyQualifiedName,
        convertFromProviderExpression: x => Type.GetType(x));

I assumed this would've been enough for Entity Framework Core to realize that Type is not an entity, but I ended up having to explicitly ignore it for this to work:

modelBuilder.Ignore<Type>();

To reduce a misspelled error on your EF Core code, you can use a code generator tool, EF Core has a command line tool for code generation, in my case I use CatFactory and with code like this we can generate code from existing database:

var connectionString = "server=(local);database=Store;integrated security=yes;";

var dbFactory = new SqlServerDatabaseFactory()
{
    ConnectionString = connectionString
};

var db = dbFactory.Import();

var project = new EfCoreProject()
{
    Name = "Store",
    Database = db,
    OutputDirectory = "C:\\Temp\\Store"
};

project.BuildFeatures();

project
    .GenerateEntities()
    .GenerateAppSettings()
    .GenerateMappingDependences()
    .GenerateMappings()
    .GenerateDbContext()
    .GenerateContracts()
    .GenerateRepositories();

You can get more information on this link: Generating Code for EF Core with CatFactory

In that way we avoid to make a mistake on writing EF Core code

Comments
  • It's seems like you have no defined a key for all your entities, you need to set key for each entity in your db context
  • I will recheck, but I think I didn't forget any primary or foreign key
  • I understand my errors, i tried to use Type for one one my properties and it ask for a primary key...
  • Same issue here. The error ist correct but could there be a hint about which entity is affected please...
  • This works for me without the Ignore<Type> statement (.NET Core 2.2)