Queryable.All<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) Metoda

Definice

Určuje, zda všechny prvky sekvence splní podmínku.Determines whether all the elements of a sequence satisfy a condition.

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

Parametry typu

TSource

Typ prvků source .The type of the elements of source.

Parametry

source
IQueryable<TSource>

Sekvence, jejíž prvky mají být testovány na podmínku.A sequence whose elements to test for a condition.

predicate
Expression<Func<TSource,Boolean>>

Funkce pro otestování každého prvku podmínky.A function to test each element for a condition.

Návraty

Boolean

true Pokud každý prvek zdrojové sekvence předá test v zadaném predikátu, nebo pokud je sekvence prázdná; v opačném případě false .true if every element of the source sequence passes the test in the specified predicate, or if the sequence is empty; otherwise, false.

Výjimky

source nebo predicate je null .source or predicate is null.

Příklady

Následující příklad kódu ukazuje, jak použít All<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) k určení, zda všechny prvky v sekvenci splní podmínku.The following code example demonstrates how to use All<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) to determine whether all the elements in a sequence satisfy a condition.

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

public static void AllEx1()
{
    // Create an array of Pets.
    Pet[] pets = { new Pet { Name="Barley", Age=10 },
                   new Pet { Name="Boots", Age=4 },
                   new Pet { Name="Whiskers", Age=6 } };

    // Determine whether all pet names in the array start with 'B'.
    bool allStartWithB =
        pets.AsQueryable().All(pet => pet.Name.StartsWith("B"));

    Console.WriteLine(
        "{0} pet names start with 'B'.",
        allStartWithB ? "All" : "Not all");
}

// This code produces the following output:
//
//  Not all pet names start with 'B'.

Sub AllEx()
    ' Create an array of Pets.
    Dim pets() As Pet = _
        {New Pet With {.Name = "Barley", .Age = 10}, _
         New Pet With {.Name = "Boots", .Age = 4}, _
         New Pet With {.Name = "Whiskers", .Age = 6}}

    ' Determine whether all pet names in the array start with 'B'.
    Dim allStartWithB As Boolean = _
        pets.AsQueryable().All(Function(ByVal pet) pet.Name.StartsWith("B"))

    MsgBox(String.Format( _
        "{0} pet names start with 'B'.", _
        IIf(allStartWithB, "All", "Not all")))
End Sub

Public Structure Pet
    Dim Name As String
    Dim Age As Integer
End Structure

' This code produces the following output:
'
'  Not all pet names start with 'B'. 

Logická hodnota, kterou All<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) Metoda vrátí, se obvykle používá v predikátu where klauzule ( Where klauzule v Visual Basic) nebo přímém volání Where metody.The Boolean value that the All<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) method returns is typically used in the predicate of a where clause (Where clause in Visual Basic) or a direct call to the Where method. Následující příklad ukazuje toto použití All metody.The following example demonstrates this use of the All 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 AllEx2()
{
    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 Pet { Name = "Belle", Age = 8} }},
          new Person { LastName = "Philips",
                       Pets = new Pet[] { new Pet { Name = "Sweetie", Age = 2},
                                          new Pet { Name = "Rover", Age = 13}} }
        };

    // Determine which people have pets that are all older than 5.
    IEnumerable<string> names = from person in people
                                where person.Pets.AsQueryable().All(pet => pet.Age > 5)
                                select person.LastName;

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

    /* This code produces the following output:
     *
     * Haas
     * Antebi
     */
}
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 AllEx2()
    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 Pet With {.Name = "Belle", .Age = 8}}}, _
          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 pets that are all older than 5.
    Dim names = From person In people _
                Where person.Pets.AsQueryable().All(Function(pet) pet.Age > 5) _
                Select person.LastName

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

    ' This code produces the following output:
    '
    ' Haas
    ' Antebi

End Sub

Poznámky

Tato metoda má alespoň jeden parametr typu, Expression<TDelegate> jehož argumentem typu je jeden z Func<T,TResult> typů.This method has at least one parameter of type Expression<TDelegate> whose type argument is one of the Func<T,TResult> types. Pro tyto parametry můžete předat výraz lambda a bude zkompilován do Expression<TDelegate> .For these parameters, you can pass in a lambda expression and it will be compiled to an Expression<TDelegate>.

All<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>)Metoda generuje MethodCallExpression , který reprezentuje volání All<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) sebe sama jako vytvořenou obecnou metodu.The All<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) method generates a MethodCallExpression that represents calling All<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) itself as a constructed generic method. Poté předá MethodCallExpression Execute<TResult>(Expression) metodě IQueryProvider reprezentované Provider vlastností source parametru.It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the source parameter.

Chování dotazu, ke kterému dochází v důsledku provádění stromu výrazů, který představuje volání, All<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) závisí na implementaci source typu parametru.The query behavior that occurs as a result of executing an expression tree that represents calling All<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) depends on the implementation of the source parameter's type. Očekávané chování je, že určuje, zda všechny prvky v source splňuje podmínky v predicate .The expected behavior is that it determines if all the elements in source satisfy the condition in predicate.

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