应用迁移时出现关系错误 - EF Core 5.0

Question

我正在尝试模拟由 3 个实体组成的场景，即 - User、Post 和 Comment

user 可以在该帖子上创作post，另一个user 或相同的user 可以comment。

因此User 实体可以在其下关联多个帖子。并且Comment 实体可以有多个 cmet 与不同用户的单个帖子相关联。

我正在尝试使用 EF Core 5.0 在我的模型上应用迁移，但出现错误 -

'Post' 和 'User.Comments' 之间以及 'Post.Author' 和 'User' 之间的关系都可以使用 {'AuthorId'} 作为外键。

要解决此问题，请在至少一个关系的“OnModelCreating”中明确配置外键属性。

---

这里是模型类（用户、帖子和评论）-

public class BaseEntity<TKey>
{
    public TKey Id { get; set; }
    public DateTime CreatedAt { get; set; }
    public DateTime? UpdatedAt { get; set; }
}

public class User : BaseEntity<int>
{
    [Required]
    [MaxLength(256)]
    public string Username { get; set; }

    [Required]
    [EmailAddress]
    [MaxLength(256)]
    public string Email { get; set; }

    [Required]
    [DataType(DataType.Password)]
    public string Password { get; set; }
    
    public IReadOnlyList<Post> Posts { get; set; }
    
    public IReadOnlyList<Comment> Comments { get; set; }
}

public class Post : BaseEntity<int>
{
    [Required]
    [MaxLength(200)]
    public string Title { get; set; }

    [Required]
    [MaxLength(512)]
    public string Content { get; set; }

    public User Author { get; set; }
}

public class Comment : BaseEntity<int>
{
    [Required]
    [MaxLength(512)]
    public string Body { get; set; }

    public User Author { get; set; }
    
    public Post Post { get; set; }
}

这里是上下文类 -

public class BlogContext : DbContext
{
    public BlogContext(DbContextOptions options): base(options)
    {
    }

    public DbSet<User> Users { get; set; }
    public DbSet<Post> Posts { get; set; }
    public DbSet<Comment> Comments { get; set; }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder
            .Entity<User>()
            .HasIndex(x => x.Username)
            .IsUnique();

        modelBuilder
            .Entity<User>()
            .HasIndex(x => x.Email)
            .IsUnique();

        modelBuilder
           .Entity<User>()
           .HasMany(u => u.Posts)
           .WithOne()
           .OnDelete(DeleteBehavior.Cascade);

        modelBuilder
           .Entity<User>()
           .HasMany(u => u.Comments)
           .WithOne()
           .OnDelete(DeleteBehavior.Cascade);

        modelBuilder
            .Entity<Post>()
            .HasOne(p => p.Author)
            .WithMany();

        modelBuilder
            .Entity<Comment>()
            .HasOne(c => c.Post)
            .WithMany(p => p.Comments);
          
        modelBuilder
            .Entity<Comment>()
            .HasOne(c => c.Author)
            .WithMany();

        base.OnModelCreating(modelBuilder);
    }
}

任何人都可以纠正错误并提供最佳实践来模拟这种情况

Answer 1

您必须添加 UserId 和 PostId 键

public class Post : BaseEntity<int>
{

    [Required]
    [MaxLength(200)]
    public string Title { get; set; }

    [Required]
    [MaxLength(512)]
    public string Content { get; set; }

    public int UserId{ get; set; }

    [ForeignKey(nameof(UserId))]
    [InverseProperty(nameof(User.Posts))]
    public User Author { get; set; }

     public ICollection<Comment> Comments { get; set; }
}

public class Comment : BaseEntity<int>
{
    [Required]
    [MaxLength(512)]
    public string Body { get; set; }

    public int UserId{ get; set; }
    [ForeignKey(nameof(UserId))]
    [InverseProperty(nameof(User.Comments))]
    public User Author { get; set; }
    
   public int PostId{ get; set; }
    [ForeignKey(nameof(PostId))]
    [InverseProperty(nameof(Post.Comments))]
    public Post CommentPost { get; set; }
}