在EF代碼中嵌套Linq第一個

Question

我想知道是否有可能有雙重嵌套linq同態。

我有以下對象（我使用EF代碼第一）

public class Team 
{ 
    public int TeamId { get; set; } 
    public sting Name {get;set;} 
    public virtual ICollection<Person> People 
} 

public class Person 
{ 
    public int PersonId { get; set; } 

    [ForeignKey("Team")] 
    public int? TeamId { get; set; } 
    public Team Team { get; set; } 

    public virtual ICollection<Paper> Papers 
} 

public class Paper 
{ 
    public int PaperId { get; set; } 

    [ForeignKey("Person")] 
    public int? PersonId { get; set; } 
    public Person Person { get; set; } 

    public virtual ICollection<Paper> People 
} 

然後我用下面的LINQ statemate創建一個對象

(from t in db.Teams 
select new TeamPapers 
{ 
    TeamName = t.Name 
    PaperTotal = t.People.Select(p=>p.Papers).Count() 
}).ToList() 

但PaperTotal只返回數ICollection < Paper>不是這些集合中的論文總數。我想知道是否有人知道如何做到這一點？

Answer 1

您是否嘗試過SelectMany而不是select？

(from t in db.Teams 
select new TeamPapers 
{ 
    TeamName = t.Name 
    PaperTotal = t.People.**SelectMany**(p=>p.Papers).Count() 
}).ToList() 

Answer 2

目前您檢索號集合的，這是因爲你選擇從每個人單集合，然後指望他們。相反，你要覆蓋所有集合算Paper情況下 - 你可以通過使用SelectMany()代替它變平採集你投射到：

(from t in db.Teams 
select new TeamPapers 
{ 
    TeamName = t.Name 
    PaperTotal = t.People.SelectMany(p=>p.Papers).Count() 
}).ToList()