Question

LINQ split error

Asked by: arthrex

Hi experts,

I try to split entries of a collection using LINQ.
I think it works how I try to do it, but the cast doesn't seem to be possible.

But I don't get why, because my class implements List<QuoteDTO>

This is the error:
Error      1      Cannot convert type 'System.Collections.Generic.List<System.Collections.Generic.List<SLQuoteApp.Web.DTOs.Activities.QuoteDTO>>' to 'System.Collections.Generic.List<SLQuoteApp.Web.DTOs.Activities.Quotes.QuoteCollection>'      C:\Applications\SLQuoteApp\SLQuoteApp.Web\DTOs\Activities\Quotes\QuoteCollection.cs      34      20      SLQuoteApp.Web

public class QuoteCollection : List<QuoteDTO>
{      
 
      public List<QuoteCollection> splitIntoCountries()
        {
            return (List<QuoteCollection>) (this.GroupBy(n => n.Staat)
                                             .Select(n => n.ToList())
                                             .ToList());
        }
}

                                  
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Asked On
2009-10-02 at 08:28:01ID24780514
Topics

Language Integrated Query - LINQ

,

C# Programming Language

Participating Experts
1
Points
500
Comments
4

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Answers

 

by: naspinskiPosted on 2009-10-02 at 08:37:32ID: 25478921

when you do 'Select(n => n.ToList())' you are selecting a list of lists, so you are not simply returning a List<QuoteCollection> - what are you trying to return?

 

by: arthrexPosted on 2009-10-02 at 23:56:31ID: 25484185

I know.
What I'm returning is this:
List<List<QuoteDTO>>

But my class QuoteCollection extends the class List<QuoteDTO>.

So why can't I cast the above statement to List<QuoteCollection>?

Am I missing something?

 

by: naspinskiPosted on 2009-10-03 at 00:23:13ID: 25484233

You cant cast the above into a List<List<QuoteDTO>> into a List<QuoteCollection> because they are not the same thing.  You are returning "public List<QuoteCollection>" NOT a "public List<List<<QuoteCollection>>" - maybe you want to try something like this:

public List<List<QuoteCollection>> splitIntoCountries()
{
  return this.GroupBy(n => n.Staat).Select(n => n.ToList().Cast<QuoteCollection>()).ToList();
}
//did not test, but I think it gets the point across

                                              
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by: arthrexPosted on 2009-10-05 at 07:01:56ID: 25495284

Thanks for the hint.
Below the exact way

        public List<QuoteCollection> splitIntoCountries()
        {
            List<QuoteCollection> lists =  (List<QuoteCollection>) (this.GroupBy(n => n.Staat)
                                             .Select(n => n.ToList())
                                            .ToList().Cast<QuoteCollection>());
            return lists;
        }

                                              
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