EntityFrameworkCore：如何使用ForeignKey反向查找實體？

Question

當我有兩個實體：

public class Org : BaseEntity, IEntityBase 
    { 
     public string Name { get; set; } 
    } 

public class Portfolio : BaseEntity, IEntityBase 
    { 
     public string Name { get; set; } 
     public int OrganizationId { get; set; } 

     [ForeignKey("OrganizationId")] 
     public virtual Org Organization { get; set; } 
     public bool IsPrivate { get; set; } 
    } 

當我取回網頁API控制器內部投資組合數據，我可以這樣做：dbSet.Include(a=>a.Organization)加載相關Org數據。有沒有一種方法可以從Org中「反轉」這種查找（加載所有Portfolio的外鍵到被查看的Org）？

當我添加一個List<Portfolio> Portfolios {get;set;}屬性時，我遇到了循環引用無盡循環：我假設因爲兩個實體相互引用。

我檢索數據的方式是這樣的：

public virtual IEnumerable<T> AllIncluding(params Expression<Func<T, object>>[] includeProperties) 
    { 
     IQueryable<T> query = _context.Set<T>(); 
     foreach (var includeProperty in includeProperties) 
     { 
      query = query.Include(includeProperty); 
     } 
     return query.AsEnumerable(); 
    } 

OrgRepo.AllIncluding(a=>a.Portfolios)

Answer 1

它應該是爲增加投資組合的清單，ORG一樣簡單。

public class Org : BaseEntity, IEntityBase 
{ 
    public string Name { get; set; } 
    public List <Portfolio> Portfolios { get; set; } //Note, the naming should be plural, to indicate one to many 
} 

https://docs.microsoft.com/en-us/ef/core/modeling/relationships有關於此的更多信息。

Answer 2

例子：

public class Org : BaseEntity, IEntityBase 
    { 
     public string Name { get; set; } 
     public ICollection<Portfolio> Portfolios { get; set; } 
    } 

    public class Portfolio : BaseEntity, IEntityBase 
    { 
     public string Name { get; set; } 
     public int OrganizationId { get; set; } 

     [ForeignKey("OrganizationId")] 
     public virtual Org Organization { get; set; } 
     public bool IsPrivate { get; set; } 
    } 

用途：

var orgs= _context.Portfolios.Include(a=>a.Organization).select(s=>s.Organization); 
var portfolios= _context.Orgs .Include(a=>a.Portfolios).SelectMany(s=>s.Portfolios);