WithRequired（）未定义扩展方法

Question

我一直在搜索过去三个小时，试图弄清发生了什么，最后不得不分解并发布问题。

我试图将WithRequired（）/ HasRequired（）添加到ApplicationUser的模型构建器中，但是它告诉我未定义。

我是在这里只是完全无知，还是在.Net Core / EF Core框架中改变了这一点？

应用用户：

public class ApplicationUser : IdentityUser
{
    [Required]
    [StringLength(100)]
    public string Name { get; set; }

    public ICollection<Following> Followers { get; set; }

    public ICollection<Following> Followees { get; set; }

    public ApplicationUser()
    {
        Followers = new Collection<Following>();
        Followees = new Collection<Following>();
    }
}

following.cs：

public class Following
{
    [Key]
    [Column(Order = 1)]
    public string FollowerId { get; set; }

    [Key]
    [Column(Order = 2)]
    public string FolloweeId { get; set; }

    public ApplicationUser Follower { get; set; }
    public ApplicationUser Followee { get; set; }
}

ApplicationDbContext：

public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
{
    public DbSet<Gig> Gigs { get; set; }
    public DbSet<Genre> Genres { get; set; }

    public DbSet<Attendance> Attendances { get; set; }

    public DbSet<Following> Followings { get; set; }

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

    protected override void OnModelCreating(ModelBuilder builder)
    {
        base.OnModelCreating(builder);
        // Customize the ASP.NET Identity model and override the defaults if needed.
        // For example, you can rename the ASP.NET Identity table names and more.
        // Add your customizations after calling base.OnModelCreating(builder);

        builder.Entity<Attendance>()
            .HasKey(c => new { c.GigId, c.AttendeeId });

        builder.Entity<ApplicationUser>()
            .HasMany(u => u.Followers);

        builder.Entity<ApplicationUser>()
            .HasMany(u => u.Followees);
    }
}

当我尝试添加WithRequired（）/ HasRequired（）时出错：

Answer 1

您可以使用

builder.Entity<ApplicationUser>()
        .HasMany(u => u.Followers).WithOne(tr => tr.Follower).IsRequired()

装的

builder.Entity<ApplicationUser>()
        .HasMany(u => u.Followers).WithRequired(tr => tr.Follower)

Answer 2

你需要这样写才能得到WithRequired()（根据你的Following班级）

builder.Entity<Following>().HasRequired(u=>u.Follower).WithMany(u=>u.Followers);

请重写实体以获得正确的输出。

IE

public class ApplicationUser : IdentityUser{
  [Required]
  [StringLength(100)]
  public string Name { get; set; }

  public Following Follower { get; set; }
}

public class Following{
    [Key]
    [Column(Order = 1)]
    public string FollowerId { get; set; }

    [Key]
    [Column(Order = 2)]
    public string FolloweeId { get; set; }

    public ICollection<ApplicationUser> Followers { get; set; }
}

那么OnModelCreating就会是

protected override void OnModelCreating(ModelBuilder builder)
{
        builder.Entity<ApplicationUser>()
    .HasRequired(u=>u.Follower)
        .HasMany(u => u.Followers);
}