Queryable.Where Queryable.Where Queryable.Where Queryable.Where Method

Definición

Filtra una secuencia de valores en función de un predicado.Filters a sequence of values based on a predicate.

Sobrecargas

Where<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) Where<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) Where<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) Where<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>)

Filtra una secuencia de valores en función de un predicado.Filters a sequence of values based on a predicate.

Where<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32,Boolean>>) Where<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32,Boolean>>) Where<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32,Boolean>>) Where<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32,Boolean>>)

Filtra una secuencia de valores en función de un predicado.Filters a sequence of values based on a predicate. El índice de cada elemento se usa en la lógica de la función de predicado.Each element's index is used in the logic of the predicate function.

Where<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) Where<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) Where<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) Where<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>)

Filtra una secuencia de valores en función de un predicado.Filters a sequence of values based on a predicate.

public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
 static System::Linq::IQueryable<TSource> ^ Where(System::Linq::IQueryable<TSource> ^ source, System::Linq::Expressions::Expression<Func<TSource, bool> ^> ^ predicate);
public static System.Linq.IQueryable<TSource> Where<TSource> (this System.Linq.IQueryable<TSource> source, System.Linq.Expressions.Expression<Func<TSource,bool>> predicate);
static member Where : System.Linq.IQueryable<'Source> * System.Linq.Expressions.Expression<Func<'Source, bool>> -> System.Linq.IQueryable<'Source>
<Extension()>
Public Function Where(Of TSource) (source As IQueryable(Of TSource), predicate As Expression(Of Func(Of TSource, Boolean))) As IQueryable(Of TSource)

Parámetros de tipo

TSource

Tipo de los elementos de source.The type of the elements of source.

Parámetros

source
IQueryable<TSource>

IQueryable<T> que se va a filtrar.An IQueryable<T> to filter.

predicate
Expression<Func<TSource,Boolean>>

Función para probar cada elemento de una condición.A function to test each element for a condition.

Devoluciones

IQueryable<TSource>

IQueryable<T> que contiene los elementos de la secuencia de entrada que satisfacen la condición especificada en predicate.An IQueryable<T> that contains elements from the input sequence that satisfy the condition specified by predicate.

Excepciones

source o predicate es null.source or predicate is null.

Ejemplos

En el ejemplo de código siguiente se muestra Where<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) cómo utilizar para filtrar una secuencia.The following code example demonstrates how to use Where<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) to filter a sequence.

List<string> fruits =
    new List<string> { "apple", "passionfruit", "banana", "mango", 
                       "orange", "blueberry", "grape", "strawberry" };

// Get all strings whose length is less than 6.
IEnumerable<string> query =
    fruits.AsQueryable().Where(fruit => fruit.Length < 6);

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

/*
    This code produces the following output:

    apple
    mango
    grape
*/

Dim fruits As New List(Of String)(New String() _
                        {"apple", "passionfruit", "banana", "mango", _
                         "orange", "blueberry", "grape", "strawberry"})

' Get all strings whose length is less than 6.
Dim query = fruits.AsQueryable().Where(Function(fruit) fruit.Length < 6)

' Display the results.
Dim output As New System.Text.StringBuilder
For Each fruit As String In query
    output.AppendLine(fruit)
Next
MsgBox(output.ToString())

' This code produces the following output:

' apple
' mango
' grape

Comentarios

Este método tiene al menos un parámetro de tipo Expression<TDelegate> cuyo argumento de tipo es uno de Func<T,TResult> los 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 Where<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) método genera un MethodCallExpression que representa la Where<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) llamada a sí mismo como un método genérico construido.The Where<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) method generates a MethodCallExpression that represents calling Where<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) itself as a constructed generic method. A continuación, pasa MethodCallExpression el CreateQuery(Expression) al método de IQueryProvider representado por la Provider propiedad del 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 Where<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) representa la llamada depende de la implementación del tipo source del parámetro.The query behavior that occurs as a result of executing an expression tree that represents calling Where<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) depends on the implementation of the type of the source parameter. El comportamiento esperado es que devuelva los elementos de source que satisfacen la condición especificada predicatepor.The expected behavior is that it returns the elements from source that satisfy the condition specified by predicate.

Where<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32,Boolean>>) Where<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32,Boolean>>) Where<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32,Boolean>>) Where<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32,Boolean>>)

Filtra una secuencia de valores en función de un predicado.Filters a sequence of values based on a predicate. El índice de cada elemento se usa en la lógica de la función de predicado.Each element's index is used in the logic of the predicate function.

public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
 static System::Linq::IQueryable<TSource> ^ Where(System::Linq::IQueryable<TSource> ^ source, System::Linq::Expressions::Expression<Func<TSource, int, bool> ^> ^ predicate);
public static System.Linq.IQueryable<TSource> Where<TSource> (this System.Linq.IQueryable<TSource> source, System.Linq.Expressions.Expression<Func<TSource,int,bool>> predicate);
static member Where : System.Linq.IQueryable<'Source> * System.Linq.Expressions.Expression<Func<'Source, int, bool>> -> System.Linq.IQueryable<'Source>
<Extension()>
Public Function Where(Of TSource) (source As IQueryable(Of TSource), predicate As Expression(Of Func(Of TSource, Integer, Boolean))) As IQueryable(Of TSource)

Parámetros de tipo

TSource

Tipo de los elementos de source.The type of the elements of source.

Parámetros

source
IQueryable<TSource>

IQueryable<T> que se va a filtrar.An IQueryable<T> to filter.

predicate
Expression<Func<TSource,Int32,Boolean>>

Función que va a probar cada elemento para determinar si satisface una condición; el segundo parámetro de la función representa el índice del elemento de la secuencia de origen.A function to test each element for a condition; the second parameter of the function represents the index of the element in the source sequence.

Devoluciones

IQueryable<TSource>

IQueryable<T> que contiene los elementos de la secuencia de entrada que satisfacen la condición especificada en predicate.An IQueryable<T> that contains elements from the input sequence that satisfy the condition specified by predicate.

Excepciones

source o predicate es null.source or predicate is null.

Ejemplos

En el ejemplo de código siguiente se muestra Where<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32,Boolean>>) cómo utilizar para filtrar una secuencia basada en un predicado que incorpora el índice de cada elemento.The following code example demonstrates how to use Where<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32,Boolean>>) to filter a sequence based on a predicate that incorporates the index of each element.

int[] numbers = { 0, 30, 20, 15, 90, 85, 40, 75 };

// Get all the numbers that are less than or equal to
// the product of their index in the array and 10.
IEnumerable<int> query =
    numbers.AsQueryable()
    .Where((number, index) => number <= index * 10);

foreach (int number in query)
    Console.WriteLine(number);

/*
    This code produces the following output:

    0
    20
    15
    40
*/

Dim numbers() As Integer = {0, 30, 20, 15, 90, 85, 40, 75}

' Get all the numbers that are less than or equal to
' the product of their index in the array and 10.
Dim query = numbers.AsQueryable() _
    .Where(Function(number, index) number <= index * 10)

' Display the results.
Dim output As New System.Text.StringBuilder
For Each number As Integer In query
    output.AppendLine(number)
Next
MsgBox(output.ToString())

' This code produces the following output:

' 0
' 20
' 15
' 40

Comentarios

Este método tiene al menos un parámetro de tipo Expression<TDelegate> cuyo argumento de tipo es uno de Func<T,TResult> los 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 Where<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32,Boolean>>) método genera un MethodCallExpression que representa la Where<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32,Boolean>>) llamada a sí mismo como un método genérico construido.The Where<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32,Boolean>>) method generates a MethodCallExpression that represents calling Where<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32,Boolean>>) itself as a constructed generic method. A continuación, pasa MethodCallExpression el CreateQuery(Expression) al método de IQueryProvider representado por la Provider propiedad del 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 Where<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32,Boolean>>) representa la llamada depende de la implementación del tipo source del parámetro.The query behavior that occurs as a result of executing an expression tree that represents calling Where<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32,Boolean>>) depends on the implementation of the type of the source parameter. El comportamiento esperado es que devuelva los elementos de source que satisfacen la condición especificada predicatepor.The expected behavior is that it returns the elements from source that satisfy the condition specified by predicate. El índice de cada elemento de origen se proporciona como el segundo argumento predicatede.The index of each source element is provided as the second argument to predicate.

Se aplica a