The result of a query cannot be enumerated more than once
I am using the entity framework (ef) and am getting the following error:
"The result of a query cannot be enumerated more than once.".
I have a repository class which contains the ef data context. I then have a controller class (not to be confused with MVC controllers) which contains an instance of the repository. So far so good... I have a search method on the controller which is supposed to return an array of RadComboBoxItemData
, which is used to populate a Telerik RadComboBox control.
public RadComboBoxItemData[] Search(int id, string searchText)
{
var query = context.Search(id, searchText);
List<RadComboBoxItemData> result = new List<RadComboBoxItemData>();
foreach (var item in query)
{
RadComboBoxItemData itemData = new RadComboBoxItemData();
itemData.Text = ""; // assign some text here..;
itemData.Value = ""; /*assign some value here..*/
result.Add(itemData);
}
return result.ToArray();
}
When I debug my code, I can get into the foreach loop, but then I get an error saying:
An exception of type 'System.InvalidOperationException' occurred in System.Data.Entity.dll but was not handled in user code
Additional information: The result of a query cannot be enumerated more than once.
My entity uses a function import of an existing stored proc.
// EF repository method calling the function imported method on the data context.
public IEnumerable<SearchItem> Search(int id, string searchText)
{
return this.entityContext.Search(id, searchText);
}
The function import Search
calls a stored precedure to return a collection of SearchItem
.
I have a feeling that the foreach loop can't iterate because of something with the ef.
Solution 1:
Try explicitly enumerating the results by calling ToList()
.
Change
foreach (var item in query)
to
foreach (var item in query.ToList())
Solution 2:
Try replacing this
var query = context.Search(id, searchText);
with
var query = context.Search(id, searchText).tolist();
and everything will work well.