How To give alias in linq when use with WCF

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I am using LINQ with WCF
in the .dbml file I dragged the sql table, my code in IService1.cs file is:

XML

[OperationContract]
List<ASX_D> ASX_D12(String tablename, String company);

and my code in Service1.svc.cs is

XML

public List<ASX_D> ASX_D12(string tablename, string company)
{
    var q = (from p in db.ASX_Ds
            where p.ASX_D_name == company
            select new      
    {
      qq=p.ASX_D_close ,
      ff=p.ASX_D_date,
      ss=p.ASX_D_exchange,
      oo=p.ASX_D_high,
      gg=p.ASX_D_low,
      fg=p.ASX_D_name,
      dfgdfg=p.ASX_D_open
      qweqwe=p.ASX_D_sector,
      cvbcvb=p.ASX_D_symbol,
      aedasew=p.ASX_D_time,
      sdfsdf=p.ASX_D_type,ruwoeru=p.ASX_D_volume
   });
   return q.ToList();

but it give the error

XML

Cannot implicitly convert type 'System.Collections.Generic.List<AnonymousType#2>' to 'System.Collections.Generic.List<SilverlightProjectwithWCF.Web.ASX_D>' C:\Documents and Settings\hgtech\Desktop\SilverlightProjectwithWCF\SilverlightProjectwithWCF.Web\Service1.svc.cs    134 20  SilverlightProjectwithWCF.Web

How we can give an alias to columns in a LINQ query?

Posted 27-Apr-11 0:19am

Rohit from Delhi

Updated 27-Apr-11 2:38am

Keith Barrow

v4

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Comments

Keith Barrow 27-Apr-11 8:39am

I improved the English a little and formatted the code for you.

Bruno Tagliapietra 27-Apr-11 8:52am

linq is c# not sql, you have no aliases. If your method return type is List<TypeName> you must return a list of TypeName, not a list of anonymous type. So in your select you should do something like "... select new ASX_D{ PublicProperty1 = value1, publicField = value2, }" ... ...

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Keith Barrow · Answer 1 · 2011-04-27T02:53:00

This code should work:

C#

var q = (from p in db.ASX_Ds
         where p.ASX_D_name == company
          select p;
return q.ToList();

The intermediate anonymous type is not required, in fact it can't be cast to the return type in the generic, so the type aliasing you want is a non-starter in a strongly OO language like C#.

If you want to restrict the fields you should declare a DataContract[^]with the fields you want and convert, you can write convertor method and an call
q.ToList().ConvertAll<datacontracttype>(ConversionFunction);

See List<T>.ConvertAll<TOutput> Method [^]

Such conversion is worthwhile even if you want to send all the data as it de-couples your interface from your object model and database implementation and allows versioning of the service.