Question

我有这个简单的代码：

namespace EFCollectionTest
{
    public class Parent
    {
        public Guid ID { get; set; }
        protected internal virtual ICollection<Child1> Children1 { get; set; }
        protected internal virtual ICollection<Child2> Children2 { get; set; }

        public void AddChild1(Child1 child)
        {
            Children1.Add(child);
        }

        public void AddChild2(Child2 child)
        {
            Children2.Add(child);
        }
    }

    public abstract class Child_Base
    {
        public Guid ID { get; set; }
    }

    public abstract class Child_Base<TParent> : Child_Base
        where TParent : class
    {
        public Guid ParentID { get; set; }
        public virtual TParent Parent { get; set; }

        void SetParent(TParent value)
        {
            Parent = value;
        }
    }

    public class Child1 : Child_Base<Parent>
    {
    }

    public class Child2 : Child_Base<Parent>
    {
    }

    public class ExampleContext2 : DbContext
    {
        public DbSet<Parent> Parents { get; set; }
        public DbSet<Child1> Children1 { get; set; }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            modelBuilder.Entity<Parent>().Property(t => t.ID).HasDatabaseGeneratedOption(System.ComponentModel.DataAnnotations.Schema.DatabaseGeneratedOption.Identity);
            modelBuilder.Entity<Child1>().Property(t => t.ID).HasDatabaseGeneratedOption(System.ComponentModel.DataAnnotations.Schema.DatabaseGeneratedOption.Identity);
            modelBuilder.Entity<Child2>().Property(t => t.ID).HasDatabaseGeneratedOption(System.ComponentModel.DataAnnotations.Schema.DatabaseGeneratedOption.Identity);

            modelBuilder.Entity<Child1>()
                .Property(t => t.ParentID);

            modelBuilder.Entity<Child2>()
                .Property(t => t.ParentID);

            modelBuilder.Entity<Parent>()
                .HasMany(t => t.Children1)
                .WithRequired(t => t.Parent)
                .HasForeignKey(d => d.ParentID);

            modelBuilder.Entity<Parent>()
                .HasMany(t => t.Children2)
                .WithRequired(t => t.Parent)
                .HasForeignKey(d => d.ParentID);
        }
    }
}

这种情况看起来非常简单，一个Parent有一个Child1集合和一个Child2集合。

问题是，当实体框架构建其模型时，抛出此异常：

在模型生成期间检测到一个或多个验证错误：父级：FromRole：NavigationProperty“父级”无效。在AssociationType'Parent_Children2'中输入FromRole'Parent_Children2_Target'的'Child2'必须与声明此NavigationProperty的类型'Child1'完全匹配。

完整堆栈跟踪是：

System.Data.Entity.ModelConfiguration.ModelValidationException:
One or more validation errors were detected during model generation:
Parent: FromRole: NavigationProperty 'Parent' is not valid.
Type 'Child2' of FromRole 'Parent_Children2_Target' in AssociationType
'Parent_Children2' must exactly match with the type 'Child1' on which this
NavigationProperty is declared on.

at System.Data.Entity.Core.Metadata.Edm.EdmModel.Validate()
at System.Data.Entity.DbModelBuilder.Build(DbProviderManifest providerManifest, DbProviderInfo providerInfo)
at System.Data.Entity.DbModelBuilder.Build(DbConnection providerConnection)
at System.Data.Entity.Internal.LazyInternalContext.CreateModel(LazyInternalContext internalContext)
at System.Data.Entity.Internal.RetryLazy`2.GetValue(TInput input)
at System.Data.Entity.Internal.LazyInternalContext.InitializeContext()
at System.Data.Entity.Internal.LazyInternalContext.get_ModelBeingInitialized()
at System.Data.Entity.Infrastructure.EdmxWriter.WriteEdmx(DbContext context, XmlWriter writer)
at System.Data.Entity.Utilities.DbContextExtensions.<>c__DisplayClass1.<GetModel>b__0(XmlWriter w)
at System.Data.Entity.Utilities.DbContextExtensions.GetModel(Action`1 writeXml)
at System.Data.Entity.Utilities.DbContextExtensions.GetModel(DbContext context)
at System.Data.Entity.Migrations.DbMigrator..ctor(DbMigrationsConfiguration configuration, DbContext usersContext, DatabaseExistenceState existenceState, Boolean calledByCreateDatabase)
at System.Data.Entity.Migrations.DbMigrator..ctor(DbMigrationsConfiguration configuration)
at System.Data.Entity.Migrations.Design.MigrationScaffolder..ctor(DbMigrationsConfiguration migrationsConfiguration)
at System.Data.Entity.Migrations.Design.ToolingFacade.ScaffoldRunner.Run()
at System.AppDomain.DoCallBack(CrossAppDomainDelegate callBackDelegate)
at System.AppDomain.DoCallBack(CrossAppDomainDelegate callBackDelegate)
at System.Data.Entity.Migrations.Design.ToolingFacade.Run(BaseRunner runner)
at System.Data.Entity.Migrations.Design.ToolingFacade.Scaffold(String migrationName, String language, String rootNamespace, Boolean ignoreChanges)
at System.Data.Entity.Migrations.AddMigrationCommand.Execute(String name, Boolean force, Boolean ignoreChanges)
at System.Data.Entity.Migrations.AddMigrationCommand.<>c__DisplayClass2.<.ctor>b__0()
at System.Data.Entity.Migrations.MigrationsDomainCommand.Execute(Action command)

这个映射有什么问题，因为它似乎非常直接，并且显然没有关于Child1 / Child2的异常声明这样的混淆？

如何在典型的父/子情境中映射Child的不同子类的集合？

0 个答案: