Queryable.OfType<TResult>(IQueryable) Method

Definition

Filtra los elementos de IQueryable en función de un tipo especificado.Filters the elements of an IQueryable based on a specified type.

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

Type Parameters

TResult

El tipo según el cual se van a filtrar los elementos de la secuencia.The type to filter the elements of the sequence on.

Parameters

source
IQueryable

IQueryable cuyos elementos se van a filtrar.An IQueryable whose elements to filter.

Returns

IQueryable<TResult>

Colección que contiene los elementos de source que son de tipo TResult.A collection that contains the elements from source that have type TResult.

Exceptions

source es null.source is null.

Examples

En el ejemplo de código siguiente se muestra cómo usar OfType para filtrar los elementos que no son de tipo PropertyInfo de una lista de elementos de tipo MemberInfo.The following code example demonstrates how to use OfType to filter out elements that are not of type PropertyInfo from a list of elements of type MemberInfo.

// Create a list of MemberInfo objects.
List<System.Reflection.MemberInfo> members = typeof(String).GetMembers().ToList();

// Return only those items that can be cast to type PropertyInfo.
IQueryable<System.Reflection.PropertyInfo> propertiesOnly =
    members.AsQueryable().OfType<System.Reflection.PropertyInfo>();

Console.WriteLine("Members of type 'PropertyInfo' are:");
foreach (System.Reflection.PropertyInfo pi in propertiesOnly)
    Console.WriteLine(pi.Name);

/*
    This code produces the following output:

    Members of type 'PropertyInfo' are:
    Chars
    Length
*/

' Create a list of MemberInfo objects.
Dim members As List(Of System.Reflection.MemberInfo) = GetType(String).GetMembers().ToList()

' Return only those items that can be cast to type PropertyInfo.
Dim propertiesOnly As IQueryable(Of System.Reflection.PropertyInfo) = _
        members.AsQueryable().OfType(Of System.Reflection.PropertyInfo)()

Dim output As New System.Text.StringBuilder
output.AppendLine("Members of type 'PropertyInfo' are:")
For Each pi As System.Reflection.PropertyInfo In propertiesOnly
    output.AppendLine(pi.Name)
Next

' Display the output.
MsgBox(output.ToString())

' This code produces the following output:

' Members of type 'PropertyInfo' are:
' Chars
' Length

Remarks

El método OfType genera un MethodCallExpression que representa la llamada a OfType como un método genérico construido.The OfType method generates a MethodCallExpression that represents calling OfType 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 OfType 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 OfType depends on the implementation of the type of the source parameter. El comportamiento esperado es que filtre los elementos de source que no sean de tipo TResult.The expected behavior is that it filters out any elements in source that are not of type TResult.

Applies to