创建用户关系表

Question

我想在ASP.NET核心中创建一个用户关系表，但遇到了一些问题。如果因为这个原因我必须禁用级联删除，我如何防止孤立？

错误：

Introducing FOREIGN KEY constraint 'FK_UserRelationships_AspNetUsers_User2Id' on table 'UserRelationships' may cause cycles or multiple cascade paths. Specify ON DELETE NO ACTION or ON UPDATE NO ACTION, or modify other FOREIGN KEY constraints.

ApplicationDbContext.cs：

public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
{
    public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options)
        : base(options)
    {
    }

    protected override void OnModelCreating(ModelBuilder builder)
    {
        base.OnModelCreating(builder);
        builder.Entity<UserRelationship>().HasKey(x => new { x.User1Id, x.User2Id });
    }

    public DbSet<UserRelationship> UserRelationships { get; set; }
}

我目前的模型：

public class UserRelationship
{
    public byte RelationshipType { get; set; }
    public ApplicationUser User1 { get; set; }
    public string User1Id { get; set; }
    public ApplicationUser User2 { get; set; }
    public string User2Id { get; set; }
}

Answer 1

您拥有所需的ApplicationUsers，因此EF会将缺省情况下的delete级联两次到同一个类(参见here。

你需要告诉它不要：

builder.Entity<UserRelationship>().HasOne(ur => ur.User1).WithMany().HasForeignKey(ur => ur.UserId1).WillCascadeOnDelete(false);

builder.Entity<UserRelationship>().HasOne(ur => ur.User2).WithMany().HasForeignKey(ur => ur.UserId2).WillCascadeOnDelete(false);