有没有办法简化这个 linq

Question

我有 2 个布尔标志，需要相应地过滤我的集合。必须有一种更清洁的方法来做到这一点。如果有人能指出我正确的方向，我将不胜感激。谢谢。

var _filteredEvents = from ev in _events 
                      select ev;
if (!queueEmail) // don't queue email
{
    if (!queueTextMessaging) // don't queue textmessaging
    {
        _filteredEvents = from ev in _events
                              where ev.QueueTypeEnumText != QueueType.TextMessage.ToString() 
                                && ev.QueueTypeEnumText !=QueueType.Email.ToString()
                              select ev;
    }
    else
    {
         _filteredEvents = from ev in _events
                              where ev.QueueTypeEnumText != QueueType.Email.ToString()
                              select ev;
    }
}
else //queue email
{
    if (!queueTextMessaging) //don't queue textmessaging
    {
        _filteredEvents = from ev in _events
                          where ev.QueueTypeEnumText != QueueType.TextMessage.ToString()
                          select ev;
    }
}

Answer 1

由于 LINQ 使用延迟执行，因此您只需更改对象的 Where() 扩展名，然后随时重新分配它：

var _filteredEvents = _events; 
if (!queueEmail)
     _filteredEvents =  _filteredEvents.Where(ev => ev.QueueTypeEnumText != QueueType.Email.ToString());
if (!queueTextMessaging)
     _filteredEvents =  _filteredEvents.Where(ev => ev.QueueTypeEnumText != QueueType.TextMessage.ToString());

Answer 2

您可以创建一个 where 子句：

where 
     (queueTextMessaging || ev.QueueTypeEnumText != QueueType.TextMessage.ToString())
   &&(queueEmail || ev.QueueTypeEnumText !=QueueType.Email.ToString())

Answer 3

var _filteredEvents =
  from ev in _events where (
    queueTextMessaging || ev.QueueTypeEnumText != QueueType.TextMessage.ToString() &&
    queueEmail || ev.QueueTypeEnumText !=QueueType.Email.ToString())
  select ev;

Answer 4

我只是创建一个方法来为您测试条件


var _filteredEvents = 来自 _events 中的 ev
其中测试（queueEmail，queueTextMessaging，ev）
选择电动车；


...

bool Test(bool foo, bool bar, Event ev) {...}