entity framework 列名 ID 无效（来自同一主 table 的两个外键）

Question

我收到此错误：列名称无效 'Resource_Id'。

我尝试了我在这个论坛上找到的解决方案，但没有解决我的错误。

这是我的类:

public class Task 
{
    public int Id { get; set; }

    public string Name { get; set; }
    public int ApproverResourceId { get; set; }
    public int WorkingResourceId { get; set; }

    public virtual Resource ApproverResource { get; set; }
    public virtual Resource WorkingResource { get; set; }
}

资源Class

public class Resource
{
    public int Id { get; set; }

    public DateTime CreationDate { get; set; }
    public DateTime UpdateDate { get; set; }

    public virtual ICollection<Task> Tasks { get; set; }
}

外部资源

public class ExternalResource : Resource
{
    //public int Id { get; set; }

    public string FirstName { get; set; }
    public string LastName { get; set; }
}

我在我的 CodeFirst 中添加了这个映射 Class

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Entity<Task>()
        .HasRequired(t => t.WorkingResource)
        .WithMany()
        .HasForeignKey(t => t.WorkingResourceId)
        .WillCascadeOnDelete(false);

    modelBuilder.Entity<Task>()
        .HasRequired(t => t.ApproverResource)
        .WithMany()
        .HasForeignKey(t => t.ApproverResourceId)
        .WillCascadeOnDelete(false);
}

Answer 1

您需要 2 个导航属性，因为您有 2 个外键：

public class Resource
{
    public int Id { get; set; }

    public DateTime CreationDate { get; set; }
    public DateTime UpdateDate { get; set; }

    public virtual ICollection<Task> ApproverTasks { get; set; }
    public virtual ICollection<Task> WorkingTasks { get; set; }
}

在 DbContext 中，您在 WithMany 中指定它们：

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Entity<Task>()
        .HasRequired(t => t.WorkingResource)
        .WithMany(r => r.WorkingTasks)
        .HasForeignKey(t => t.WorkingResourceId)
        .WillCascadeOnDelete(false);

    modelBuilder.Entity<Task>()
        .HasRequired(t => t.ApproverResource)
        .WithMany(r => r.ApproverTasks)
        .HasForeignKey(t => t.ApproverResourceId)
        .WillCascadeOnDelete(false);

    modelBuilder.Entity<ExternalResource>()
        .ToTable("ExternalResources");
}

由于 Table-Per-Type 继承，您需要明确告诉 table ExternalResources 的名称。

Answer 2

我不知道它是如何为您工作的，但就我而言，我必须指定注释键 + 列顺序；在你的情况下，这两个属性 "ResourceId".

我有完全相同的表配置，没有第三个 "External"。

Public class User : EntityBase
{
    [MinLength(5), MaxLength(20), Required]
    public string Login { get; set; }
    [MinLength(3), MaxLength(50),Required]
    public string Password { get; set; }
    public virtual List<FriendRequest> SenderFriendRequests { get; set; }
    public virtual List<FriendRequest> ReceiverFriendRequests { get; set; }
}

public class FriendRequest 
{
    [Key, Column(Order=0)]
    public int SenderId { get; set; }
    [Key, Column(Order=1)]
    public int ReceiverId { get; set; }
    public virtual User Sender { get; set; }
    public virtual User Receiver { get; set; }

    [Required]
    public FriendRequestStatus RequestStatus { get; set; }
}

如果我不指定这些注释，EF 会向我抛出一个 DataException 消息：

One or more validation errors were detected during model generation: Server.DAL.Context.FriendRequest: : EntityType 'FriendRequest' has no key defined. Define the key for this EntityType. FriendRequests: EntityType: EntitySet 'FriendRequests' is based on type 'FriendRequest' that has no keys defined.

entity framework 列名 ID 无效（来自同一主 table 的两个外键）

entity framework Invalid column name Id (two foreign keys from the same primary table)

asp.net-mvc

entity-framework

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