Queryable.ThenByDescending Método

public:
generic <typename TSource, typename TKey>
[System::Runtime::CompilerServices::Extension]
 static System::Linq::IOrderedQueryable<TSource> ^ ThenByDescending(System::Linq::IOrderedQueryable<TSource> ^ source, System::Linq::Expressions::Expression<Func<TSource, TKey> ^> ^ keySelector);

public static System.Linq.IOrderedQueryable<TSource> ThenByDescending<TSource,TKey> (this System.Linq.IOrderedQueryable<TSource> source, System.Linq.Expressions.Expression<Func<TSource,TKey>> keySelector);

static member ThenByDescending : System.Linq.IOrderedQueryable<'Source> * System.Linq.Expressions.Expression<Func<'Source, 'Key>> -> System.Linq.IOrderedQueryable<'Source>

<Extension()>
Public Function ThenByDescending(Of TSource, TKey) (source As IOrderedQueryable(Of TSource), keySelector As Expression(Of Func(Of TSource, TKey))) As IOrderedQueryable(Of TSource)

Parámetros de tipo

Parámetros

Devoluciones

IOrderedQueryable<TSource>

Una interfaz IOrderedQueryable<T> cuyos elementos se ordenan de manera descendente con arreglo a una clave.An IOrderedQueryable<T> whose elements are sorted in descending order according to a key.

Excepciones

Comentarios

Este método tiene al menos un parámetro de tipo Expression<TDelegate> cuyo argumento de tipo es uno de los Func<T,TResult> tipos.This method has at least one parameter of type Expression<TDelegate> whose type argument is one of the Func<T,TResult> types. Para estos parámetros, puede pasar una expresión lambda y se compilará en un Expression<TDelegate> .For these parameters, you can pass in a lambda expression and it will be compiled to an Expression<TDelegate>.

El ThenByDescending<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>) método genera un MethodCallExpression que representa la llamada a ThenByDescending<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>) sí mismo como un método genérico construido.The ThenByDescending<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>) method generates a MethodCallExpression that represents calling ThenByDescending<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>) itself as a constructed generic method. A continuación, pasa el MethodCallExpression al CreateQuery<TElement>(Expression) método de IQueryProvider representado por la Provider propiedad del source parámetro.It then passes the MethodCallExpression to the CreateQuery<TElement>(Expression) method of the IQueryProvider represented by the Provider property of the source parameter. El resultado de la llamada CreateQuery<TElement>(Expression) a se convierte al tipo IOrderedQueryable<T> y se devuelve.The result of calling CreateQuery<TElement>(Expression) is cast to type IOrderedQueryable<T> and returned.

El comportamiento de la consulta que se produce como resultado de ejecutar un árbol de expresión que representa ThenByDescending<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>) la llamada depende de la implementación del tipo del source parámetro.The query behavior that occurs as a result of executing an expression tree that represents calling ThenByDescending<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>) depends on the implementation of the type of the source parameter. El comportamiento esperado es que realiza una ordenación secundaria de los elementos de source en orden descendente, en función de la clave obtenida al invocar keySelector en cada elemento de source .The expected behavior is that it performs a secondary sort of the elements of source in descending order, based on the key obtained by invoking keySelector on each element of source. Se conservan todos los criterios de ordenación previamente establecidos.All previously established sort orders are preserved.

public:
generic <typename TSource, typename TKey>
[System::Runtime::CompilerServices::Extension]
 static System::Linq::IOrderedQueryable<TSource> ^ ThenByDescending(System::Linq::IOrderedQueryable<TSource> ^ source, System::Linq::Expressions::Expression<Func<TSource, TKey> ^> ^ keySelector, System::Collections::Generic::IComparer<TKey> ^ comparer);

public static System.Linq.IOrderedQueryable<TSource> ThenByDescending<TSource,TKey> (this System.Linq.IOrderedQueryable<TSource> source, System.Linq.Expressions.Expression<Func<TSource,TKey>> keySelector, System.Collections.Generic.IComparer<TKey> comparer);

public static System.Linq.IOrderedQueryable<TSource> ThenByDescending<TSource,TKey> (this System.Linq.IOrderedQueryable<TSource> source, System.Linq.Expressions.Expression<Func<TSource,TKey>> keySelector, System.Collections.Generic.IComparer<TKey>? comparer);

static member ThenByDescending : System.Linq.IOrderedQueryable<'Source> * System.Linq.Expressions.Expression<Func<'Source, 'Key>> * System.Collections.Generic.IComparer<'Key> -> System.Linq.IOrderedQueryable<'Source>

<Extension()>
Public Function ThenByDescending(Of TSource, TKey) (source As IOrderedQueryable(Of TSource), keySelector As Expression(Of Func(Of TSource, TKey)), comparer As IComparer(Of TKey)) As IOrderedQueryable(Of TSource)

Parámetros de tipo

Parámetros

Devoluciones

IOrderedQueryable<TSource>

Colección cuyos elementos están ordenados de manera descendente de acuerdo con una clave.A collection whose elements are sorted in descending order according to a key.

Excepciones

Ejemplos

En el ejemplo de código siguiente se muestra cómo utilizar ThenByDescending<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>, IComparer<TKey>) para realizar una ordenación secundaria de los elementos de una secuencia en orden descendente mediante un comparador personalizado.The following code example demonstrates how to use ThenByDescending<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>, IComparer<TKey>) to perform a secondary ordering of the elements in a sequence in descending order by using a custom comparer.

public class CaseInsensitiveComparer : IComparer<string>
{
    public int Compare(string x, string y)
    {
        return string.Compare(x, y, true);
    }
}

public static void ThenByDescendingEx1()
{
    string[] fruits =
    { "apPLe", "baNanA", "apple", "APple", "orange", "BAnana", "ORANGE", "apPLE" };

    // Sort the strings first ascending by their length and
    // then descending using a custom case insensitive comparer.
    IEnumerable<string> query =
        fruits.AsQueryable()
        .OrderBy(fruit => fruit.Length)
        .ThenByDescending(fruit => fruit, new CaseInsensitiveComparer());

    foreach (string fruit in query)
        Console.WriteLine(fruit);
}

/*
    This code produces the following output:

    apPLe
    apple
    APple
    apPLE
    orange
    ORANGE
    baNanA
    BAnana
*/

Class CaseInsensitiveComparer
    Implements IComparer(Of String)

    Function Compare(ByVal x As String, ByVal y As String) As Integer _
        Implements IComparer(Of String).Compare

        ' Compare values and ignore case.
        Return String.Compare(x, y, True)
    End Function
End Class

Sub ThenByDescendingEx1()
    Dim fruits() As String = _
        {"apPLe", "baNanA", "apple", "APple", "orange", "BAnana", "ORANGE", "apPLE"}

    ' Sort the strings first ascending by their length and 
    ' then descending by using a custom case insensitive comparer.
    Dim query = fruits.AsQueryable() _
        .OrderBy(Function(fruit) fruit.Length) _
        .ThenByDescending(Function(fruit) fruit, New CaseInsensitiveComparer())

    Dim output As New System.Text.StringBuilder
    For Each fruit As String In query
        output.AppendLine(fruit)
    Next

    ' Display the results.
    MsgBox(output.ToString())
End Sub

' This code produces the following output:

' apPLe
' apple
' APple
' apPLE
' orange
' ORANGE
' baNanA
' BAnana

Comentarios

Este método tiene al menos un parámetro de tipo Expression<TDelegate> cuyo argumento de tipo es uno de los Func<T,TResult> tipos.This method has at least one parameter of type Expression<TDelegate> whose type argument is one of the Func<T,TResult> types. Para estos parámetros, puede pasar una expresión lambda y se compilará en un Expression<TDelegate> .For these parameters, you can pass in a lambda expression and it will be compiled to an Expression<TDelegate>.

El ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>, IComparer<TKey>) método genera un MethodCallExpression que representa la llamada a ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>, IComparer<TKey>) sí mismo como un método genérico construido.The ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>, IComparer<TKey>) method generates a MethodCallExpression that represents calling ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>, IComparer<TKey>) itself as a constructed generic method. A continuación, pasa el MethodCallExpression al CreateQuery<TElement>(Expression) método de IQueryProvider representado por la Provider propiedad del source parámetro.It then passes the MethodCallExpression to the CreateQuery<TElement>(Expression) method of the IQueryProvider represented by the Provider property of the source parameter. El resultado de la llamada CreateQuery<TElement>(Expression) a se convierte al tipo IOrderedQueryable<T> y se devuelve.The result of calling CreateQuery<TElement>(Expression) is cast to type IOrderedQueryable<T> and returned.

El comportamiento de la consulta que se produce como resultado de ejecutar un árbol de expresión que representa ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>, IComparer<TKey>) la llamada depende de la implementación del tipo del source parámetro.The query behavior that occurs as a result of executing an expression tree that represents calling ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>, IComparer<TKey>) depends on the implementation of the type of the source parameter. El comportamiento esperado es que realiza una ordenación secundaria de los elementos de source en orden descendente, en función de la clave obtenida al invocar keySelector en cada elemento de source .The expected behavior is that it performs a secondary sort of the elements of source in descending order, based on the key obtained by invoking keySelector on each element of source. Se conservan todos los criterios de ordenación previamente establecidos.All previously established sort orders are preserved. El comparer parámetro se usa para comparar los valores de clave.The comparer parameter is used to compare key values.