ObjectQuery<T>::SelectValue<TResultType> Method (String^, array<ObjectParameter^>^)
Limits the query results to only the property specified in the projection.
Assembly: System.Data.Entity (in System.Data.Entity.dll)
public: generic<typename TResultType> ObjectQuery<TResultType>^ SelectValue( String^ projection, ... array<ObjectParameter^>^ parameters )
Parameters
- projection
-
Type:
System::String^
The projection list.
- parameters
-
Type:
array<System.Data.Objects::ObjectParameter^>^
An optional set of query parameters that should be in scope when parsing.
Return Value
Type: System.Data.Objects::ObjectQuery<TResultType>^A new ObjectQuery<T> instance of a type compatible with the specific projection. The returned ObjectQuery<T> is equivalent to the original instance with SELECT VALUE applied.
Type Parameters
- TResultType
The type of the ObjectQuery<T> returned by the SelectValue<TResultType> method.
| Exception | Condition |
|---|---|
| ArgumentNullException | projection is null. -or- parameters is null. |
| ArgumentException | The projection is an empty string. |
SelectValue<TResultType> is used to return values that are simple types, entity types, or complex types. Use the Select method for projections that require a row type instead of a value type. For more information, see Object Queries.
The SelectValue<TResultType> method applies the projection specified by the projection parameter. The ObjectQuery<T> returned by the SelectValue<TResultType> method must be of a value type that is compatible with the projection and must be the same type as the type of SelectValue<TResultType>.
This example is based on the AdventureWorks Sales Model. The example creates a new ObjectQuery<T> that contains results that are a sequence of ProductID values projected from the results of the existing query.
Available since 3.5