DbContext: Identity value generation cannot be used because the property type is byte

Steps to reproduce

Trying to create a table where primary key is of type tinyint and is identity. Tried with anotations [Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)] and fluent API UseSqlServerIdentityColumn()

The issue

I get this error: Identity value generation cannot be used for the property 'Id' on entity type 'Cargo' because the property type is 'byte'. Identity value generation can only be used with signed integer properties.

Exception message:
Stack trace:
Project DFWeb (.NETCoreApp,Version=v1.1) was previously compiled. Skipping compilation.
dotnet : System.ArgumentException: Identity value generation cannot be used for the property 'Id' on entity type 'Cargo' because the property type is 
'byte'. Identity value generation can only be used with signed integer properties.
At line:1 char:1
+ dotnet ef migrations add "Inicial"
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (System.Argument...ger properties.:String) [], RemoteException
    + FullyQualifiedErrorId : NativeCommandError
 
   at Microsoft.EntityFrameworkCore.Metadata.SqlServerPropertyAnnotations.SetValueGenerationStrategy(Nullable`1 value)


   at Microsoft.EntityFrameworkCore.Metadata.Internal.SqlServerPropertyBuilderAnnotations.ValueGenerationStrategy(Nullable`1 value)


   at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.SqlServerValueGenerationStrategyConvention.Apply(InternalPropertyBuilder propertyBuilder, 
DatabaseGeneratedAttribute attribute, MemberInfo clrMember)


   at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.PropertyAttributeConvention`1.Apply(InternalPropertyBuilder propertyBuilder)


   at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.ConventionDispatcher.OnPropertyAdded(InternalPropertyBuilder propertyBuilder)


   at Microsoft.EntityFrameworkCore.Metadata.Internal.EntityType.AddProperty(String name, Type propertyType, MemberInfo memberInfo, ConfigurationSource 
configurationSource, Boolean runConventions)


   at Microsoft.EntityFrameworkCore.Metadata.Internal.EntityType.AddProperty(MemberInfo memberInfo, ConfigurationSource configurationSource, Boolean 
runConventions)


   at Microsoft.EntityFrameworkCore.Metadata.Internal.InternalEntityTypeBuilder.Property(Property existingProperty, String propertyName, Type propertyType, 
MemberInfo clrProperty, Nullable`1 configurationSource)


   at Microsoft.EntityFrameworkCore.Metadata.Internal.InternalEntityTypeBuilder.Property(String propertyName, Type propertyType, MemberInfo clrProperty, 
Nullable`1 configurationSource)


   at Microsoft.EntityFrameworkCore.Metadata.Internal.InternalEntityTypeBuilder.Property(MemberInfo clrProperty, ConfigurationSource configurationSource)


   at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.PropertyDiscoveryConvention.Apply(InternalEntityTypeBuilder entityTypeBuilder)


   at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.ConventionDispatcher.OnEntityTypeAdded(InternalEntityTypeBuilder entityTypeBuilder)


   at Microsoft.EntityFrameworkCore.Metadata.Internal.Model.AddEntityType(EntityType entityType, Boolean runConventions)


   at Microsoft.EntityFrameworkCore.Metadata.Internal.InternalModelBuilder.Entity(Type type, ConfigurationSource configurationSource, Boolean runConventions)


   at Microsoft.EntityFrameworkCore.ModelBuilder.Entity(Type type)

   at Microsoft.EntityFrameworkCore.Infrastructure.ModelSource.FindSets(ModelBuilder modelBuilder, DbContext context)


   at Microsoft.EntityFrameworkCore.Infrastructure.Internal.RelationalModelSource.FindSets(ModelBuilder modelBuilder, DbContext context)


   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)


Identity value generation cannot be used for the property 'Id' on entity type 'Cargo' because the property type is 'byte'. Identity value generation can only be used with signed integer properties.

Further technical details

SQL server does allow tinyint to be used with IDENTITY. As a workaround I used this: [Key, Column(TypeName = "tinyint IDENTITY(1,1)")]

EF Core version: 1.1 Operating system: Windows 10 Visual Studio version: VS2015 Community

Best regards.

[ErikEJ]

@spyofborg in other words, just use tinyint and assign the key values yourself

[cjcfreitas]

@ajcvickers One can always use a larger format. I use tinyint as PK in small master tables (e.g. document types, wharehouses, VAT taxes) when I am sure there will be only a few items. This will be FK in larger tables. I know there are different opinions about this, but I usually favor using the most restrictive data-type available whenever I am sure it wont overflow (Hard disk space is cheap but it’s not the only issue).