Queryable.Concat<TSource>(IQueryable<TSource>, IEnumerable<TSource>) 方法
定义
连接两个序列。Concatenates two sequences.
public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
static System::Linq::IQueryable<TSource> ^ Concat(System::Linq::IQueryable<TSource> ^ source1, System::Collections::Generic::IEnumerable<TSource> ^ source2);
public static System.Linq.IQueryable<TSource> Concat<TSource> (this System.Linq.IQueryable<TSource> source1, System.Collections.Generic.IEnumerable<TSource> source2);
static member Concat : System.Linq.IQueryable<'Source> * seq<'Source> -> System.Linq.IQueryable<'Source>
<Extension()>
Public Function Concat(Of TSource) (source1 As IQueryable(Of TSource), source2 As IEnumerable(Of TSource)) As IQueryable(Of TSource)
类型参数
- TSource
输入序列中的元素的类型。The type of the elements of the input sequences.
参数
- source1
- IQueryable<TSource>
要连接的第一个序列。The first sequence to concatenate.
- source2
- IEnumerable<TSource>
要与第一个序列连接的序列。The sequence to concatenate to the first sequence.
返回
- IQueryable<TSource>
一个包含两个输入序列的连接元素的 IQueryable<T>。An IQueryable<T> that contains the concatenated elements of the two input sequences.
例外
source1 或 source2 为 null。source1 or source2 is null.
示例
下面的代码示例演示如何使用 Concat<TSource>(IQueryable<TSource>, IEnumerable<TSource>) 来连接两个序列。The following code example demonstrates how to use Concat<TSource>(IQueryable<TSource>, IEnumerable<TSource>) to concatenate two sequences.
class Pet
{
public string Name { get; set; }
public int Age { get; set; }
}
// This method creates and returns an array of Pet objects.
static Pet[] GetCats()
{
Pet[] cats = { new Pet { Name="Barley", Age=8 },
new Pet { Name="Boots", Age=4 },
new Pet { Name="Whiskers", Age=1 } };
return cats;
}
// This method creates and returns an array of Pet objects.
static Pet[] GetDogs()
{
Pet[] dogs = { new Pet { Name="Bounder", Age=3 },
new Pet { Name="Snoopy", Age=14 },
new Pet { Name="Fido", Age=9 } };
return dogs;
}
public static void ConcatEx1()
{
Pet[] cats = GetCats();
Pet[] dogs = GetDogs();
// Concatenate a collection of cat names to a
// collection of dog names by using Concat().
IEnumerable<string> query =
cats.AsQueryable()
.Select(cat => cat.Name)
.Concat(dogs.Select(dog => dog.Name));
foreach (string name in query)
Console.WriteLine(name);
}
// This code produces the following output:
//
// Barley
// Boots
// Whiskers
// Bounder
// Snoopy
// Fido
' This method creates and returns an array of Pet objects.
Shared Function GetCats() As Pet()
Dim cats() As Pet = _
{New Pet With {.Name = "Barley", .Age = 8}, _
New Pet With {.Name = "Boots", .Age = 4}, _
New Pet With {.Name = "Whiskers", .Age = 1}}
Return cats
End Function
' This method creates and returns an array of Pet objects.
Shared Function GetDogs() As Pet()
Dim dogs() As Pet = _
{New Pet With {.Name = "Bounder", .Age = 3}, _
New Pet With {.Name = "Snoopy", .Age = 14}, _
New Pet With {.Name = "Fido", .Age = 9}}
Return dogs
End Function
Shared Sub ConcatEx1()
Dim cats() As Pet = GetCats()
Dim dogs() As Pet = GetDogs()
' Concatenate a collection of cat names to a
' collection of dog names by using Concat().
Dim query As IEnumerable(Of String) = _
cats.AsQueryable() _
.Select(Function(cat) cat.Name) _
.Concat(dogs.Select(Function(dog) dog.Name))
For Each name As String In query
MsgBox(name)
Next
End Sub
Structure Pet
Dim Name As String
Dim Age As Integer
End Structure
' This code produces the following output:
'
' Barley
' Boots
' Whiskers
' Bounder
' Snoopy
' Fido
注解
Concat<TSource>(IQueryable<TSource>, IEnumerable<TSource>)方法生成一个 MethodCallExpression ,它表示调用 Concat<TSource>(IQueryable<TSource>, IEnumerable<TSource>) 自身作为构造的泛型方法。The Concat<TSource>(IQueryable<TSource>, IEnumerable<TSource>) method generates a MethodCallExpression that represents calling Concat<TSource>(IQueryable<TSource>, IEnumerable<TSource>) itself as a constructed generic method. 然后,它将传递 MethodCallExpression 给 CreateQuery<TElement>(Expression) IQueryProvider 由参数的属性表示的的方法 Provider source1 。It then passes the MethodCallExpression to the CreateQuery<TElement>(Expression) method of the IQueryProvider represented by the Provider property of the source1 parameter.
由于执行表示调用的表达式树而发生的查询行为 Concat<TSource>(IQueryable<TSource>, IEnumerable<TSource>) 取决于参数类型的实现 source1 。The query behavior that occurs as a result of executing an expression tree that represents calling Concat<TSource>(IQueryable<TSource>, IEnumerable<TSource>) depends on the implementation of the type of the source1 parameter. 预期的行为是,中的元素 source2 连接到的元素 source1 以创建新序列。The expected behavior is that the elements in source2 are concatenated to those of source1 to create a new sequence.