Queryable.Cast<TResult>(IQueryable) Method

Definition

Convierte los elementos de IQueryable en el tipo especificado.Converts the elements of an IQueryable to the specified type.

public:
generic <typename TResult>
[System::Runtime::CompilerServices::Extension]
 static System::Linq::IQueryable<TResult> ^ Cast(System::Linq::IQueryable ^ source);
public static System.Linq.IQueryable<TResult> Cast<TResult> (this System.Linq.IQueryable source);
static member Cast : System.Linq.IQueryable -> System.Linq.IQueryable<'Result>
<Extension()>
Public Function Cast(Of TResult) (source As IQueryable) As IQueryable(Of TResult)

Type Parameters

TResult

Tipo al que se convierten los elementos de source.The type to convert the elements of source to.

Parameters

source
IQueryable

IQueryable que contiene los elementos que se van a convertir.The IQueryable that contains the elements to be converted.

Returns

IQueryable<TResult>

IQueryable<T> que contiene cada elemento de la secuencia de origen convertido en el tipo especificado.An IQueryable<T> that contains each element of the source sequence converted to the specified type.

Exceptions

source es null.source is null.

Un elemento de la secuencia no se puede convertir al tipo TResult.An element in the sequence cannot be cast to type TResult.

Examples

En el ejemplo de código siguiente se muestra cómo usar Cast<TResult>(IQueryable) para convertir objetos de una secuencia en un tipo String.The following code example demonstrates how to use Cast<TResult>(IQueryable) to convert objects in a sequence to type String.


// Create a list of objects.
List<object> words =
    new List<object> { "green", "blue", "violet" };

// Cast the objects in the list to type 'string'
// and project the first letter of each string.
IEnumerable<string> query =
    words.AsQueryable()
    .Cast<string>()
    .Select(str => str.Substring(0, 1));

foreach (string s in query)
    Console.WriteLine(s);

/*  This code produces the following output:

    g
    b
    v
*/


' Create a list of objects.
Dim words As New List(Of Object)(New Object() {"green", "blue", "violet"})

' Cast the objects in the list to type 'string'
' and project the first letter of each string.
Dim query As IEnumerable(Of String) = _
    words.AsQueryable() _
            .Cast(Of String)() _
            .Select(Function(str) str.Substring(0, 1))

For Each s As String In query
    MsgBox(s)
Next

' This code produces the following output:
'
' g
' b
' v

Remarks

El método Cast<TResult>(IQueryable) genera un MethodCallExpression que representa la llamada a Cast<TResult>(IQueryable) como un método genérico construido.The Cast<TResult>(IQueryable) method generates a MethodCallExpression that represents calling Cast<TResult>(IQueryable) itself as a constructed generic method. A continuación, pasa el MethodCallExpression al método CreateQuery(Expression) de la IQueryProvider representada por la propiedad Provider del parámetro source.It then passes the MethodCallExpression to the CreateQuery(Expression) method of the IQueryProvider represented by the Provider property of the source parameter.

El comportamiento de la consulta que se produce como resultado de ejecutar un árbol de expresión que representa la llamada a Cast<TResult>(IQueryable) depende de la implementación del tipo del parámetro source.The query behavior that occurs as a result of executing an expression tree that represents calling Cast<TResult>(IQueryable) depends on the implementation of the type of the source parameter. El comportamiento esperado es que convierta los valores de source al tipo TResult.The expected behavior is that it converts the values in source to type TResult.

Applies to