Question

我无法将var转换回List<CustomObject>。

private void PopulateChart(List<CustomObject> rawData)
 {
   var groupedByCategory1 = rawData.GroupBy(co => co.Category1)
   //List<CustomObject> data = groupedByCategory1.GroupBy(co => co.Category1).ToList();    
 }

注意：从rawData我必须获取Groupby数据。再次使用该结果我必须对数据进行分组。

Answer 1

Linq GroupBy返回System.Linq.IQueryable<IGrouping<TKey,TSource>>。因此，您应该从组中选择一些数据：

List<CustomObject> data = groupedByCategory1
     .GroupBy(co => co.Category1)
     .Select(grp => new CustomObject 
          {
              Category1 = grp.Key
          }
     .ToList();

Answer 2

 var data = groupedByCategory1
         .GroupBy(co => co.Category1)
         .Select(grp => new 
              {
                  Category1 = grp.Key// This is the key that you used to group
                  groupList=grp.ToList();//This will be the list of CustomObject
              }
         .ToList();

实际上，GroupBy将您的列表分组到Category1相同的另一个列表中。

您可以按如下所示访问它

foreach (var group in data)
{// This group is List<CustomObject>. If you don't want to access it like this, whats the meaning of group by?
  var groupKey=group.Category1;
  foreach(CustomObject myObj in group.groupList)
   {

   }
}

Answer 3

你试过吗

var groupedByCategory1 = rawData
   .GroupBy(co => co.Category1)    
   .SelectMany(c => c)
   .ToList();

将var转换为c＃</t>中的List <t>

3 个答案: