Queryable.Any Metodo

Definizione

Determina se un qualsiasi elemento di una sequenza IQueryable<T> esiste o soddisfa una condizione.Determines whether any element of an IQueryable<T> sequence exists or satisfies a condition.

Overload

Any<TSource>(IQueryable<TSource>)

Determina se una sequenza contiene elementi.Determines whether a sequence contains any elements.

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

Determina un qualsiasi elemento di una sequenza soddisfa una condizione.Determines whether any element of a sequence satisfies a condition.

Any<TSource>(IQueryable<TSource>)

Determina se una sequenza contiene elementi.Determines whether a sequence contains any elements.

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

Parametri di tipo

TSource

Tipo degli elementi di source.The type of the elements of source.

Parametri

source
IQueryable<TSource>

Una sequenza da verificare per controllare se è vuota.A sequence to check for being empty.

Restituisce

Boolean

true se la sequenza di origine contiene elementi; in caso contrario, false.true if the source sequence contains any elements; otherwise, false.

Eccezioni

source è null.source is null.

Esempio

Nell'esempio di codice riportato di seguito viene illustrato come utilizzare Any<TSource>(IQueryable<TSource>) per determinare se una sequenza contiene elementi.The following code example demonstrates how to use Any<TSource>(IQueryable<TSource>) to determine whether a sequence contains any elements.

List<int> numbers = new List<int> { 1, 2 };

// Determine if the list contains any elements.
bool hasElements = numbers.AsQueryable().Any();

Console.WriteLine("The list {0} empty.",
    hasElements ? "is not" : "is");

// This code produces the following output:
//
// The list is not empty.
Dim numbers As New List(Of Integer)(New Integer() {1, 2})

' Determine if the list contains any elements.
Dim hasElements As Boolean = numbers.AsQueryable().Any()

MsgBox(String.Format("The list {0} empty.", _
    IIf(hasElements, "is not", "is")))

' This code produces the following output:
'
' The list is not empty.

Il valore booleano Any<TSource>(IQueryable<TSource>) restituito dal metodo viene in genere utilizzato nel predicato di una where clausola ( Where clausola in Visual Basic) o di una chiamata diretta al Where<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) metodo.The Boolean value that the Any<TSource>(IQueryable<TSource>) method returns is typically used in the predicate of a where clause (Where clause in Visual Basic) or a direct call to the Where<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) method. Nell'esempio seguente viene illustrato l'utilizzo del Any metodo.The following example demonstrates this use of the Any method.

class Pet
{
    public string Name { get; set; }
    public int Age { get; set; }
}
class Person
{
    public string LastName { get; set; }
    public Pet[] Pets { get; set; }
}

public static void AnyEx2()
{
    List<Person> people = new List<Person>
        { new Person { LastName = "Haas",
                       Pets = new Pet[] { new Pet { Name="Barley", Age=10 },
                                          new Pet { Name="Boots", Age=14 },
                                          new Pet { Name="Whiskers", Age=6 }}},
          new Person { LastName = "Fakhouri",
                       Pets = new Pet[] { new Pet { Name = "Snowball", Age = 1}}},
          new Person { LastName = "Antebi",
                       Pets = new Pet[] { }},
          new Person { LastName = "Philips",
                       Pets = new Pet[] { new Pet { Name = "Sweetie", Age = 2},
                                          new Pet { Name = "Rover", Age = 13}} }
        };

    // Determine which people have a non-empty Pet array.
    IEnumerable<string> names = from person in people
                                where person.Pets.AsQueryable().Any()
                                select person.LastName;

    foreach (string name in names)
        Console.WriteLine(name);

    /* This code produces the following output:

       Haas
       Fakhouri
       Philips
    */
}
Structure Pet
    Public Name As String
    Public Age As Integer
End Structure

Structure Person
    Public LastName As String
    Public Pets() As Pet
End Structure

Sub AnyEx2()
    Dim people As New List(Of Person)(New Person() _
        {New Person With {.LastName = "Haas", _
                          .Pets = New Pet() {New Pet With {.Name = "Barley", .Age = 10}, _
                                             New Pet With {.Name = "Boots", .Age = 14}, _
                                             New Pet With {.Name = "Whiskers", .Age = 6}}}, _
          New Person With {.LastName = "Fakhouri", _
                           .Pets = New Pet() {New Pet With {.Name = "Snowball", .Age = 1}}}, _
          New Person With {.LastName = "Antebi", _
                           .Pets = New Pet() {}}, _
          New Person With {.LastName = "Philips", _
                           .Pets = New Pet() {New Pet With {.Name = "Sweetie", .Age = 2}, _
                                              New Pet With {.Name = "Rover", .Age = 13}}}})

    ' Determine which people have a non-empty Pet array.
    Dim names = From person In people _
                Where person.Pets.AsQueryable().Any() _
                Select person.LastName

    For Each name As String In names
        Console.WriteLine(name)
    Next

    ' This code produces the following output:
    '
    ' Haas
    ' Fakhouri
    ' Philips

End Sub

Commenti

Il Any<TSource>(IQueryable<TSource>) metodo genera un oggetto MethodCallExpression che rappresenta la chiamata a Any<TSource>(IQueryable<TSource>) se stesso come metodo generico costruito.The Any<TSource>(IQueryable<TSource>) method generates a MethodCallExpression that represents calling Any<TSource>(IQueryable<TSource>) itself as a constructed generic method. Passa quindi al MethodCallExpression Execute<TResult>(Expression) metodo dell'oggetto IQueryProvider rappresentato dalla Provider proprietà del source parametro.It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the source parameter.

Il comportamento della query che si verifica in seguito all'esecuzione di un albero delle espressioni che rappresenta la chiamata Any<TSource>(IQueryable<TSource>) dipende dall'implementazione del tipo di source parametro.The query behavior that occurs as a result of executing an expression tree that represents calling Any<TSource>(IQueryable<TSource>) depends on the implementation of the type of the source parameter. Il comportamento previsto è che determina se source contiene elementi.The expected behavior is that it determines if source contains any elements.

Si applica a

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

Determina un qualsiasi elemento di una sequenza soddisfa una condizione.Determines whether any element of a sequence satisfies a condition.

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

Parametri di tipo

TSource

Tipo degli elementi di source.The type of the elements of source.

Parametri

source
IQueryable<TSource>

Una sequenza i cui elementi sono da testare rispetto a una condizione.A sequence whose elements to test for a condition.

predicate
Expression<Func<TSource,Boolean>>

Funzione per testare ogni elemento rispetto a una condizione.A function to test each element for a condition.

Restituisce

Boolean

true se gli elementi nella sequenza di origine superano il test per il predicato specificato; in caso contrario, false.true if any elements in the source sequence pass the test in the specified predicate; otherwise, false.

Eccezioni

source o predicate è null.source or predicate is null.

Esempio

Nell'esempio di codice riportato di seguito viene illustrato come utilizzare Any<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) per determinare se un elemento di una sequenza soddisfa una condizione.The following code example demonstrates how to use Any<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) to determine whether any element in a sequence satisfies a condition.

class Pet
{
    public string Name { get; set; }
    public int Age { get; set; }
    public bool Vaccinated { get; set; }
}

public static void AnyEx3()
{
    // Create an array of Pet objects.
    Pet[] pets =
        { new Pet { Name="Barley", Age=8, Vaccinated=true },
          new Pet { Name="Boots", Age=4, Vaccinated=false },
          new Pet { Name="Whiskers", Age=1, Vaccinated=false } };

    // Determine whether any pets over age 1 are also unvaccinated.
    bool unvaccinated =
        pets.AsQueryable().Any(p => p.Age > 1 && p.Vaccinated == false);

    Console.WriteLine(
        "There {0} unvaccinated animals over age one.",
        unvaccinated ? "are" : "are not any");
}

// This code produces the following output:
//
//  There are unvaccinated animals over age one.
Structure Pet
    Dim Name As String
    Dim Age As Integer
    Dim Vaccinated As Boolean
End Structure

Shared Sub AnyEx3()
    ' Create an array of Pet objects.
    Dim pets() As Pet = _
        {New Pet With {.Name = "Barley", .Age = 8, .Vaccinated = True}, _
         New Pet With {.Name = "Boots", .Age = 4, .Vaccinated = False}, _
         New Pet With {.Name = "Whiskers", .Age = 1, .Vaccinated = False}}

    ' Determine whether any pets over age 1 are also unvaccinated.
    Dim unvaccinated As Boolean = _
    pets.AsQueryable().Any(Function(p) p.Age > 1 And p.Vaccinated = False)

    MsgBox(String.Format( _
        "There {0} unvaccinated animals over age one.", _
        IIf(unvaccinated, "are", "are not any") _
    ))
End Sub

' This code produces the following output:
'
'  There are unvaccinated animals over age one.

Commenti

Questo metodo ha almeno un parametro di tipo Expression<TDelegate> il cui argomento di tipo è uno dei Func<T,TResult> tipi.This method has at least one parameter of type Expression<TDelegate> whose type argument is one of the Func<T,TResult> types. Per questi parametri, è possibile passare un'espressione lambda che verrà compilata in un oggetto Expression<TDelegate> .For these parameters, you can pass in a lambda expression and it will be compiled to an Expression<TDelegate>.

Il Any<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) metodo genera un oggetto MethodCallExpression che rappresenta la chiamata a Any<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) se stesso come metodo generico costruito.The Any<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) method generates a MethodCallExpression that represents calling Any<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) itself as a constructed generic method. Passa quindi al MethodCallExpression Execute<TResult>(Expression) metodo dell'oggetto IQueryProvider rappresentato dalla Provider proprietà del source parametro.It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the source parameter.

Il comportamento della query che si verifica in seguito all'esecuzione di un albero delle espressioni che rappresenta la chiamata Any<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) dipende dall'implementazione del tipo di source parametro.The query behavior that occurs as a result of executing an expression tree that represents calling Any<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) depends on the implementation of the type of the source parameter. Il comportamento previsto prevede che determini se uno degli elementi di source soddisfi la condizione specificata da predicate .The expected behavior is that it determines if any of the elements of source satisfy the condition specified by predicate.

Si applica a