Question

public class Folder
{
    [Key]
    public string Name { get; set; }

    public virtual ICollection<File> Files { get; set; }
}

public class File
{
    [Key, Column(Order = 0)]
    public string FolderName { get; set; }
    [Key, Column(Order = 1)]
    public DateTime FileName { get; set; }

    public virtual Folder Folder { get; set; }
}

Chanllange 来装饰File类的方法，以便：

 new File() {Folder = folder, FileName= "bla-bla"};

按folder.Name

的值自动设置File对象的FolderName属性

是否可以覆盖属性？

能力水平2

public class Folder
{
    [Key, Column(Order = 0)]
    public string PC { get; set; }
    [Key, Column(Order = 1)]
    public string Name { get; set; }

    public virtual ICollection<File> Files { get; set; }
}

public class File
{
    [Key, Column(Order = 0)]
    public string PC { get; set; }
[Key, Column(Order = 1)]
    public string FolderName { get; set; }
    [Key, Column(Order = 2)]
    public DateTime FileName { get; set; }

    public virtual Folder Folder { get; set; }
}

同样的问题如何在指令

之后训练模型自动设置外键

new File() {Folder=folder, FileName='bla-bla'}

更新非常简短，如何在属性

上写下来

HasRequired(a => a.Folder).WithMany(b => b.Files).HasForeignKey(c => new { c.Pc, c.FolderName});

Answer 1

只需将Folder属性从auto-implemented更改为包含支持字段的属性，然后在其setter中设置FolderName。还要将外键属性添加到此属性：

public class File
{
    private Folder _folder;

    [Key, Column(Order = 0)]
    public string FolderName { get; set; }
    [Key, Column(Order = 1)]
    public DateTime FileName { get; set; }

    [ForeignKey("FolderName")]
    public virtual Folder Folder
    {
        get { return _folder; }
        set
        {
            if (value == null)
                throw new ArgumentNullException();

            _folder = value;
            FolderName = _folder.Name;
        }
    }
}

1到n关系中的多个外键

1 个答案: