我使用实体框架7 RC1和我有实体:INSERT语句冲突与外键约束“FK_PostTag_Tag_TagId”
public class Post {
public Int32 Id { get; set; }
public String Title { get; set; }
public virtual IList<PostTag> PostsTags { get; set; }
}
public class Tag {
public Int32 Id { get; set; }
public String Name { get; set; }
public virtual IList<PostTag> PostsTags { get; set; }
}
public class PostTag {
public Int32 PostId { get; set; }
public Int32 TagId { get; set; }
public virtual Post Post { get; set; }
public virtual Tag Tag { get; set; }
}
该机型配置了这些实体如下:
protected override void OnModelCreating(ModelBuilder builder) {
base.OnModelCreating(builder);
builder.Entity<Post>(b => {
b.ToTable("Posts");
b.HasKey(x => x.Id);
b.Property(x => x.Id).UseSqlServerIdentityColumn();
b.Property(x => x.Title).IsRequired().HasMaxLength(100);
});
builder.Entity<Tag>(b => {
b.ToTable("Tags");
b.HasKey(x => x.Id);
b.Property(x => x.Id).UseSqlServerIdentityColumn();
b.Property(x => x.Name).IsRequired().HasMaxLength(100);
});
builder.Entity<PostTag>(b => {
b.ToTable("PostsTags");
b.HasKey(x => new { x.PostId, x.TagId });
b.HasOne(x => x.Post).WithMany(x => x.PostsTags).HasForeignKey(x => x.PostId);
b.HasOne(x => x.Tag).WithMany(x => x.PostsTags).HasForeignKey(x => x.TagId);
});
}
我创建了迁移和数据库。然后我试图创建一个帖子:
Context context = new Context();
Post post = new Post {
PostsTags = new List<PostTag> {
new PostTag {
Tag = new Tag { Name = "Tag name" }
}
},
Title = "Post title"
};
context.Posts.Add(post);
await _context.SaveChangesAsync();
而且在保存我得到以下错误:
An error occurred while updating the entries.
The INSERT statement conflicted with the FOREIGN KEY constraint "FK_PostTag_Tag_TagId".
The conflict occurred in database "TestDb", table "dbo.Tags", column 'Id'.
The statement has been terminated.
有谁知道这个错误的原因是什么?
但是我想在我的模型上使用FK ...我总是有几个查询它是真的有用...顺便说一句,我从来没有与EF 6这个问题... –
在这种情况下,你有使您的外键可以为空。在你的例子中,你的PostId将为0,这是打破FK约束,因为我猜你没有0作为DB中的PostId。 –
我得到了同样的错误,甚至使两个键可空... –