ObjectQuery<T>::SelectValue<TResultType> Method (String^, array<ObjectParameter^>^)

 

Limits the query results to only the property specified in the projection.

Namespace:   System.Data.Objects
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.

No code example is currently available or this language may not be supported.

.NET Framework
Available since 3.5
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