asp.net - 身份和自定义表之间的多对多关系。 EF7-代码优先

如何在Identity 3.0的AspNetRoles和自定义表之间建立多对多关系？我想要带有PermissionId和RoleId的简单3表，类似AspNetUsersRole。我有这样的事情:

public class Permission
{
    public int PermissionId { get; set; }
    public string Name { get; set; }
    public virtual ICollection<ApplicationRole> Roles { get; set; }
}

public class ApplicationRole : IdentityRole
{
    public virtual ICollection<Permission> Permissions { get; set; }
}

但是，当我想添加迁移时，出现错误:

 Unable to determine the relationship represented by navigation property 'ApplicationRole.Permissions' of type 'ICollection<Permission>'. Either manually configure the relationship, or ignore this property from the model.

最佳答案

EF核心(EF7)当前在没有连接实体的情况下不支持多对多关系。 (Reference)

因此，您应该做的是为联接表创建一个实体类，并映射两个单独的一对多关系。喜欢;

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    modelBuilder.Entity<PostTag>()
        .HasKey(t => new { t.PostId, t.TagId });

    modelBuilder.Entity<PostTag>()
        .HasOne(pt => pt.Post)
        .WithMany(p => p.PostTags)
        .HasForeignKey(pt => pt.PostId);

    modelBuilder.Entity<PostTag>()
        .HasOne(pt => pt.Tag)
        .WithMany(t => t.PostTags)
        .HasForeignKey(pt => pt.TagId);
}

public class PostTag
{
        public int PostId { get; set; }
        public Post Post { get; set; }

        public string TagId { get; set; }
        public Tag Tag { get; set; }
}