LINQ：查询结果不能列举不止一次

Question

更多的这是我的代码

searchDataContext db = new searchDataContext(); 

    var query = (from p in db.SearchFirst(city, area) 
       select new 
       { 
        ID = p.Id, 
        Address = p.address, 
        Level = p.agahilevel 

       }); 
    int count =query.Count(); 

    // records 
    var q = query.Skip(Convert.ToInt32(start)).Take(Convert.ToInt32(width)); 

    if (q.Count() > 0) 
    { 
     int index = 0; 
     str += "["; 
     foreach (var row in q) 
     { 
      if (index == 0) 

我在此代码

The query results cannot be enumerated more than once. 

请检查并回答我有一个错误。

Answer 1

物化查询：

var addresses = (from p in db.SearchFirst(city, area) 
       select new 
       { 
        ID = p.Id, 
        Address = p.address, 
        Level = p.agahilevel 

       }) 
       .Skip(Convert.ToInt32(start)) 
       .Take(Convert.ToInt32(width)) 
       .ToList(); 

然后用Enumerable.Any，以检查其是否包含元素：

if(addresses.Any()) 
{ 
    int index = 0; // ... 
} 

Answer 2

不能使用缓存的查询，并在它们之间迭代不止一次...
做它的List<T>，再次尝试

var q = query.ToList(); // work on this 

Answer 3

如果添加.ToList()您查询您的问题将得到解决