Getting single column of a table using LINQ in Silverlight

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2.50/5 (2 votes)

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Salam.o.alaikum,

I am developing an Silverlight application, i have connected to my database through a WCF Data Service.. I can succeffuly get a table using

XML

var query1 = (from s in catx.Traders where s.BranchCode == selectedBranchCode select s)  ;
var dquery1 = (query1) as DataServiceQuery<CatsMainService.Trader> ;
dquery1.BeginExecute(AccountsLoaded, dquery1);

i want to get a single column of this table... so i tried

XML

var query1 = (from s in catx.Traders where s.BranchCode == selectedBranchCode select s.Accounts)  ;
var dquery1 = (query1) as DataServiceQuery<CatsMainService.Trader> ;
dquery1.BeginExecute(AccountsLoaded, dquery1);

'Accounts' is my column name...
I am getting nullReferenceException at BeginExecute() because query1 is not being translated.. it says
"{Error translating Linq expression to URI: Can only specify query options (orderby, where, take, skip) after last navigation.}"

I googled... and tried this thing with many other queries... but had the same exception... kindly correct me... where i m mistaking...

Thanks

Posted 19-Apr-11 21:51pm

kas07

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dasblinkenlight · Answer 1 · 2011-04-20T00:38:00

Solution 1

I would guess that CatsMainService.Trader in DataServiceQuery<CatsMainService.Trader> should be changed to the type of the Accounts column.

Posted 20-Apr-11 0:38am

dasblinkenlight

Comments

kas07 20-Apr-11 6:50am

couldnt get u bro... can u please ellaborate?

dasblinkenlight 20-Apr-11 8:46am

From here: http://msdn.microsoft.com/en-us/library/cc646677.aspx, class DataServiceQuery<TElement>, TElement [is the] type of results returned by the query. Your first query (the one that works) returns rows of type CatsMainService.Trader. Your second query returns rows of another type (whatever is the type of the Accounts column), so you should change the second line of your second example to match that type, whatever it is. For example, if s.Accounts is a string, the second line should be var dquery1 = (query1) as DataServiceQuery<string> ;