c# - 定义实体关系时如何为相关操作指定有效的顺序？

我正在尝试对包含Advertisement的List<AdImage>对象进行Upsert。 Advertisement包含一个与User对应的外键。 user可以具有零个或多个Advertisements，而Advertisement可以具有一个或多个AdImages。

Upsert失败，并显示以下内容:



内在的地方是:


advertisement的实例化非常简单:

var ad = new Advertisement
{
    AdImages = new List<AdImage>
    {
        new AdImage {Image = model.Image}
    },

    Message = model.Message,
    Title = model.Title,
    User = user,
};

_aAdAppService.UpsertAdvertisement(ad);

有问题的实体定义为:

public class User : AbpUser<Tenant, User>
{ // AbpUser is a 3rd party class which defines Id as a primary key

    public string AccessToken { get; set; }
    public long UserId { get; set; }

    public virtual List<Advertisement> Advertisements { get; set; }
}

public class Advertisement : Entity
{
    [Key]
    public long Id { get; set; }

    public string Title { get; set; }
    public string Message { get; set; }
    public List<AdImage> AdImages { get; set; }

    public virtual User User { get; set; }
}

public class AdImage : Entity
{
    [Key]
    public int Id { get; set; }
    public string Image { get; set; }

    public virtual Advertisement Advertisement { get; set; }
}

关系的定义方式如下:

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Entity<User>()
        .HasMany(u => u.Advertisements)
        .WithRequired(x => x.User);

    modelBuilder.Entity<Advertisement>()
        .HasMany(a => a.AdImages)
        .WithRequired(x => x.Advertisement);

    modelBuilder.Entity<AdImage>()
        .HasRequired(x => x.Advertisement);

    base.OnModelCreating(modelBuilder);

}

错误消息是什么意思？我看不到我的关系定义不正确。我该如何解决？

最佳答案

这只是评论，但我不能在评论中写...

这是我第一次看到异常(exception)



所以我试图重现它。

这是我实现错过的类(class)和背景的方式

public class Entity
{}

public class Tenant
{}

public class AbpUser<T1, T2>
{}



public Context(DbConnection connection)
    : base(connection, false)
{
}

public DbSet<Advertisement> Advertisements { get; set; }
public DbSet<User> Users { get; set; }
public DbSet<AdImage> AdImages { get; set; }

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Entity<User>()
        .HasMany(u => u.Advertisements)
        .WithRequired(x => x.User);

    modelBuilder.Entity<Advertisement>()
        .HasMany(a => a.AdImages)
        .WithRequired(x => x.Advertisement);

    modelBuilder.Entity<AdImage>()
        .HasRequired(x => x.Advertisement);

    base.OnModelCreating(modelBuilder);

}

这是EF在自动迁移过程中生成的DDL语句

ExecuteNonQuery==========
CREATE TABLE [AdImages] (
 [Id] int not null identity(1,1)
, [Image] text null
, [Advertisement_Id] int not null
);
ALTER TABLE [AdImages] ADD CONSTRAINT [PK_AdImages_87d4bad2] PRIMARY KEY ([Id])
ExecuteNonQuery==========
CREATE TABLE [Advertisements] (
 [Id] int not null identity(1,1)
, [Title] text null
, [Message] text null
, [User_UserId] int not null
);
ALTER TABLE [Advertisements] ADD CONSTRAINT [PK_Advertisements_5d578c9a] PRIMARY KEY ([Id])
ExecuteNonQuery==========
CREATE TABLE [Users] (
 [UserId] int not null identity(1,1)
, [AccessToken] text null
);
ALTER TABLE [Users] ADD CONSTRAINT [PK_Users_5d578c9a] PRIMARY KEY ([UserId])
ExecuteNonQuery==========
CREATE INDEX [IX_Advertisement_Id] ON [AdImages] ([Advertisement_Id])
ExecuteNonQuery==========
CREATE INDEX [IX_User_UserId] ON [Advertisements] ([User_UserId])
ExecuteNonQuery==========
ALTER TABLE [AdImages] ADD CONSTRAINT [FK_AdImages_Advertisements_Advertisement_Id] FOREIGN KEY ([Advertisement_Id]) REFERENCES [Advertisements] ([Id])
ExecuteNonQuery==========
ALTER TABLE [Advertisements] ADD CONSTRAINT [FK_Advertisements_Users_User_UserId] FOREIGN KEY ([User_UserId]) REFERENCES [Users] ([UserId])

所以，实际上一切都在意料之中。

这是我尝试过的测试

public static void Run(DbConnection connection)
{
    var ad = new Advertisement
    {
        AdImages = new List<AdImage>
        {
            new AdImage {Image = "MyImage"}
        },

        Message = "MyMessage",
        Title = "MyTitle",
        User = new User()
    };

    using (Context context = new Context(connection))
    {
        context.Advertisements.Add(ad);
        context.SaveChanges();
    }
}

在数据库上产生了这个查询

ExecuteDbDataReader==========
insert into [Users]([AccessToken])
values (null);
select [UserId]
from [Users]
where [UserId] = @@identity
ExecuteDbDataReader==========
insert into [Advertisements]([Title], [Message], [User_UserId])
values (@p0, @p1, @p2);
select [Id]
from [Advertisements]
where [Id] = @@identity
@p0 = MyTitle
@p1 = MyMessage
@p2 = 1
ExecuteDbDataReader==========
insert into [AdImages]([Image], [Advertisement_Id])
values (@p0, @p1);
select [Id]
from [AdImages]
where [Id] = @@identity
@p0 = MyImage
@p1 = 1

您的模型非常完美:)

所以问题出在别的地方。
它可能在代码中，即
-model和user来自哪里？您在Upsert中使用的是同一上下文还是其他上下文？
-您在Upsert中做什么？您是否可以取消引用(从model到新对象)？
-其他缺少的类(class)(我留空的类(class))可以吗？