添加迁移EF Core时出现奇怪错误

Posted 2021-04-11

我有一个带有核心的类库，我将它放入模型中。我已经进行了第一次迁移以测试我的模型的一部分，但经过大幅增强后，我删除了我的数据库并迁移到只有一个V1迁移。

在删除之后，当我尝试添加迁移时，我有这样的错误：

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.

我不知道为什么会出现这个错误，我的模型都有一个用DataAnnotation定义的主键

是否需要我可以提供新模型，但我添加上下文如果与此相关或可能有帮助：

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=localhostSQLEXPRESS;Database=Askmycar;Trusted_Connection=True;");

            base.OnConfiguring(optionsBuilder);
        }

    }

谢谢。

答案

在我的一个模型上，我有一个这样的属性：

public Type AvailableFor { get; set; } 

Type是一个对象，所以它等待主键我将其更改为：

public string AvailableFor { get; set; } 

和它的作品。

感谢@ H.Herzi :)

另一答案

要减少EF Core代码上的拼写错误，可以使用代码生成器工具，EF Core有一个用于代码生成的命令行工具，在我的例子中，我使用CatFactory，并且使用这样的代码，我们可以从现有数据库生成代码：

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();

您可以在此链接获得更多信息：Generating Code for EF Core with CatFactory

这样我们就可以避免在编写EF Core代码时出错

另一答案

我实际上想在我的模型中使用Type，并且我已经使用转换器初始化了属性：

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

我认为这对于实体框架核心来说已经足够意识到Type不是一个实体，但我最终必须明确地忽略它以使其工作：

modelBuilder.Ignore<Type>();