Queryable.Any Method
Definition
Important
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Determines whether any element of an IQueryable<T> sequence exists or satisfies a condition.
Overloads
| Any<TSource>(IQueryable<TSource>) |
Determines whether a sequence contains any elements. |
| Any<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>) |
Determines whether any element of a sequence satisfies a condition. |
Any<TSource>(IQueryable<TSource>)
- Source:
- Queryable.cs
- Source:
- Queryable.cs
- Source:
- Queryable.cs
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 BooleanType Parameters
- TSource
The type of the elements of source.
Parameters
- source
- IQueryable<TSource>
A sequence to check for being empty.
Returns
true if the source sequence contains any elements; otherwise, false.
Exceptions
source is null.
Examples
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.
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. 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
Remarks
The Any<TSource>(IQueryable<TSource>) method generates a MethodCallExpression that represents calling Any<TSource>(IQueryable<TSource>) itself as a constructed generic method. It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the source parameter.
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. The expected behavior is that it determines if source contains any elements.
Applies to
Any<TSource>(IQueryable<TSource>, Expression<Func<TSource,Boolean>>)
- Source:
- Queryable.cs
- Source:
- Queryable.cs
- Source:
- Queryable.cs
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 BooleanType Parameters
- TSource
The type of the elements of source.
Parameters
- source
- IQueryable<TSource>
A sequence whose elements to test for a condition.
- predicate
- Expression<Func<TSource,Boolean>>
A function to test each element for a condition.
Returns
true if any elements in the source sequence pass the test in the specified predicate; otherwise, false.
Exceptions
source or predicate is null.
Examples
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.
Remarks
This method has at least one parameter of type Expression<TDelegate> whose type argument is one of the Func<T,TResult> types. For these parameters, you can pass in a lambda expression and it will be compiled to an Expression<TDelegate>.
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. It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the source parameter.
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. The expected behavior is that it determines if any of the elements of source satisfy the condition specified by predicate.
