LINQ:选择不包含列表项的对象

Question

我正在努力与LINQ语法在这里…我想我应该把它扔在这里。我在别的地方也找不到我要找的东西。

好的，假设我得到了这个:

public class Bar
{
   public int BarId { get; set; }
}
public class Foo
{
   public List<Bar> BarList { get; set; }
}
List<Foo> fooBunch = GetABunchOfFoos(); //let's just assume I'm getting more than one
List<Foo> fooSelect = new List<Foo>;
List<Bar> filterBars = GetAFewBars(); //assume I'm getting like 2 or 3
fooSelect = (from f in fooBunch
             where !(from b in f.BarList select b.BarId).Contains(ITEM FROM filterBars.BarId)
             select f).ToList();

所以，长话短说，我想使用LINQ根据另一个列表中的对象过滤出我的对象列表。我希望这是有意义的。我想我只是在包含部分上迷路了…我不知道怎么写

Answer 1

一般情况下，您要寻找的是"Except"扩展名。

var rejectStatus = GenerateRejectStatuses();
var fullList = GenerateFullList();
var rejectList = fullList.Where(i => rejectStatus.Contains(i.Status));
var filteredList = fullList.Except(rejectList);

在本例中，GenerateRegectStatuses()应该是您希望拒绝的状态列表(或者根据您的示例更具体地说，是id的List<int>)

Answer 2

将其转储到您不想要的id的更具体的集合

var notTheseBarIds = filterBars.Select(fb => fb.BarId);

那么试试这个:

fooSelect = (from f in fooBunch
             where !notTheseBarIds.Contains(f.BarId)
             select f).ToList();

或:

fooSelect = fooBunch.Where(f => !notTheseBarIds.Contains(f.BarId)).ToList();

Answer 3

试试下面这个简单的LINQ:

//For a file list/array
var files = Directory.GetFiles(folderPath, "*.*", SearchOption.AllDirectories);
//simply use Where ! x.Contains
var notContain = files.Where(x => ! x.Contains(@"$RECYCLE.BIN")).ToList();
//Or use Except()
var containing = files.Where(x => x.Contains(@"$RECYCLE.BIN")).ToList();
    notContain = files.Except(containing).ToList();

Answer 4

我没有尝试过，所以我不保证任何东西，但是

foreach Bar f in filterBars
{
     search(f)
}
Foo search(Bar b)
{
    fooSelect = (from f in fooBunch
                 where !(from b in f.BarList select b.BarId).Contains(b.ID)
                 select f).ToList();
    return fooSelect;
}