当我在 EF Core 中添加迁移时出现“实体类型 'CustomAttributeData' 需要定义主键”错误

Question

我将我的模型放入带有 Core 的类库中。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和迁移，只进行了一次 V1 迁移。

问题是，在删除之后，当我尝试add-migration 时，我得到了这个错误：

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.

我不知道为什么会收到此错误。我所有的模型都有一个用DataAnnotation 定义的主键。

如果需要，我可以提供新模型。

如果相关/有帮助，这里是上下文：

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);
    }
}

谢谢。

Answer 1

在我的一个模型上，我有这样的属性：

public Type AvailableFor { get; set; } 

类型是一个对象，所以它在等待一个主键我把它改成：

public string AvailableFor { get; set; } 

及其作品。

感谢@H.Herzi :)

Answer 2

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));

我认为这足以让 Entity Framework Core 意识到 Type 不是实体，但我最终不得不明确地忽略它以使其正常工作：

modelBuilder.Ignore<Type>();

Answer 3

为了减少 EF Core 代码中的拼写错误，您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，使用这样的代码，我们可以从现有代码生成代码数据库：

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();

您可以通过此链接获取更多信息：Generating Code for EF Core with CatFactory

这样我们避免在编写 EF Core 代码时出错