Queryable.OfType(IQueryable) Queryable.OfType(IQueryable) Queryable.OfType(IQueryable) Queryable.OfType(IQueryable) Method

Definição

Filtra os elementos de um IQueryable com base em um 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)

Parâmetros de tipo

TResult

O tipo no qual filtrar os elementos da sequência.The type to filter the elements of the sequence on.

Parâmetros

source
IQueryable IQueryable IQueryable IQueryable

Um IQueryable cujos elementos devem ser filtrados.An IQueryable whose elements to filter.

Retornos

IQueryable<TResult>

Uma coleção que contém os elementos de source que tem o tipo TResult.A collection that contains the elements from source that have type TResult.

Exceções

Exemplos

O exemplo de código a seguir demonstra como OfType usar o para filtrar elementos que não são do PropertyInfo tipo de uma lista de elementos do MemberInfotipo.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

Comentários

O OfType método gera um MethodCallExpression que representa a OfType chamada a si próprio como um método genérico construído.The OfType method generates a MethodCallExpression that represents calling OfType itself as a constructed generic method. Em seguida, ele MethodCallExpression passa o CreateQuery(Expression) para o método IQueryProvider Provider do representado pela propriedade do source parâmetro.It then passes the MethodCallExpression to the CreateQuery(Expression) method of the IQueryProvider represented by the Provider property of the source parameter.

O comportamento da consulta que ocorre como resultado da execução de uma árvore de expressão que OfType representa a chamada depende da implementação do tipo source do parâmetro.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. O comportamento esperado é que ele filtra os elementos source que não são do tipo. TResultThe expected behavior is that it filters out any elements in source that are not of type TResult.

Aplica-se a