Queryable.Cast(IQueryable) Queryable.Cast(IQueryable) Queryable.Cast(IQueryable) Queryable.Cast(IQueryable) Method

Definición

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)

Parámetros de tipo

TResult

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

Parámetros

source
IQueryable IQueryable IQueryable IQueryable

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

Devoluciones

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.

Excepciones

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

Ejemplos

En el ejemplo de código siguiente se muestra cómo usar Cast<TResult>(IQueryable) para convertir objetos en una secuencia al 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

Comentarios

El Cast<TResult>(IQueryable) método genera una MethodCallExpression que representa la llamada 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 a la CreateQuery(Expression) método de la IQueryProvider representado por la Provider propiedad de la source parámetro.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 Cast<TResult>(IQueryable) depende de la implementación del tipo de la source parámetro.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 convierte los valores de source escriba TResult.The expected behavior is that it converts the values in source to type TResult.

Se aplica a