身份和自定义表之间的多对多关系. EF7-代码优先 [英] Many to many relation between Identity and custom table. EF7 - Code first

问题描述

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.我有这样的东西:

How can I make many to many relation between AspNetRoles from Identity 3.0 and my custom table? I want simple 3 table, with both PermissionId and RoleId, something like AspNetUsersRole. I have something like this:

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:

But when I want to add migration, I got error:

 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. 

推荐答案

EF Core (EF7)当前不支持没有联接实体的多对多关系. (参考)

EF Core (EF7) does not currently support many to many relationship without a join entity. (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；

So, what you should do is to create an entity class for the join table and mapping two separate one-to-many relationships. Like;

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; }
}

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