what is linq stored procedure result error of "The query results cannot be enumerated more than once" in foreach loop?

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hi all
i try to use foreach loop on a linq query but up this error:
"The query results cannot be enumerated more than once"
C#

string st = "Adel"; dbDidDataContext db = new dbDidDataContext(); var res = db.spJobmenu(st); foreach (var item in res) { Console.Write(item.name.ToString()); }

and it clear works on:
C#

string s = res.First().name.ToString();

Posted 13-Aug-15 4:59am

mohamadMahmodi

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Andy Lanng · Accepted Answer · 2015-08-13T05:21:00

The result set cannot be queried. It is an ISingleResult<t> which works a bit differently to IQueriable and IEnumerable.

Try adding ToList(). This will make sure that the SP has returned the data before you start iterating through it:

C#

string st = "Adel";
dbDidDataContext db = new dbDidDataContext();
var res = db.spJobmenu(st).ToList();
foreach (var item in res)
{
    Console.Write(item.name.ToString());
}

the .First() method will also cause the results to be fetched, same as ToList. That is why the example you gave works

Hope that helps ^_^
Andy