Unable to type cast <AnonymousType#1> to <WindowsFormsApplication1.Attributes> [ C#3.0 ]

I have

 List<Attributes> la = new List<Attributes>();
la = (from t in result
                 let t1 = t.AttributeCollection
                 from t2 in t1
                 where t2.AttributeCode.Equals(attributeType)
                 let t3 = t2.TimeSeriesData
                 from k in t3.ToList()
                 where k.Key.Equals(startDate) && k.Key.Equals(endDate)
                 select new
                 {
                     AttributeCode = attributeType,
                     TimeSeriesData = fn(k.Key, k.Value.ToString())
                 }).ToList<Attributes>();

I am getting the error:

'System.Collections.Generic.IEnumerable<AnonymousType#1>开发者_运维知识库;' does not contain a definition for 'ToList' and the best extension method overload 'System.Linq.Enumerable.ToList<TSource>(System.Collections.Generic.IEnumerable<TSource>)' has some invalid arguments

I understood tye error meaning but how to type cast it. I have used var and then iterating over it got the result. But without that any other way by which I can do it?

Using C# 3.0

Thanks

---

may be:

 List<Attributes> la = new List<Attributes>();
la = (from t in result
                 let t1 = t.AttributeCollection
                 from t2 in t1
                 where t2.AttributeCode.Equals(attributeType)
                 let t3 = t2.TimeSeriesData
                 from k in t3.ToList()
                 where k.Key.Equals(startDate) && k.Key.Equals(endDate)
                 select new Attributes()
                 {
                     AttributeCode = attributeType,
                     TimeSeriesData = fn(k.Key, k.Value.ToString())
                 }).ToList<Attributes>();

you are constructing anonymous type with same fields as Attributes. But they are different types and can't be cast to each other.

---

Basically save it to an anonymous list type, and then call a conversion function.

public void TestMethod(){
  List<Attributes> la = new List<Attributes>();


  var annonyType = (from t in result
             let t1 = t.AttributeCollection
             from t2 in t1
             where t2.AttributeCode.Equals(attributeType)
             let t3 = t2.TimeSeriesData
             from k in t3.ToList()
             where k.Key.Equals(startDate) && k.Key.Equals(endDate)
             select new
             {
                 AttributeCode = attributeType,
                 TimeSeriesData = fn(k.Key, k.Value.ToString())
             });

   la = annonyType.ConvertAll(x=>ConvertToAttribute(x.AttributeCode , x.TimeSeriesData ));

   ....
 //End test method
 }

  //... (where TimeSeriesDataType  = type returned by fn( 
  public Attributes ConvertToAttribute(string AttributeType, TimeSeriesDataType d){
     return new Attribute()....;

   }