Queryable.ThenBy 方法

定义

按升序对序列中的元素执行后续排序。Performs a subsequent ordering of the elements in a sequence in ascending order.

重载

ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>, IComparer<TKey>)

使用指定的比较器按升序对序列中的元素执行后续排序。Performs a subsequent ordering of the elements in a sequence in ascending order by using a specified comparer.

ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>)

根据某个键按升序对序列中的元素执行后续排序。Performs a subsequent ordering of the elements in a sequence in ascending order according to a key.

ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>, IComparer<TKey>)

使用指定的比较器按升序对序列中的元素执行后续排序。Performs a subsequent ordering of the elements in a sequence in ascending order by using a specified comparer.

public:
generic <typename TSource, typename TKey>
[System::Runtime::CompilerServices::Extension]
 static System::Linq::IOrderedQueryable<TSource> ^ ThenBy(System::Linq::IOrderedQueryable<TSource> ^ source, System::Linq::Expressions::Expression<Func<TSource, TKey> ^> ^ keySelector, System::Collections::Generic::IComparer<TKey> ^ comparer);
public static System.Linq.IOrderedQueryable<TSource> ThenBy<TSource,TKey> (this System.Linq.IOrderedQueryable<TSource> source, System.Linq.Expressions.Expression<Func<TSource,TKey>> keySelector, System.Collections.Generic.IComparer<TKey> comparer);
public static System.Linq.IOrderedQueryable<TSource> ThenBy<TSource,TKey> (this System.Linq.IOrderedQueryable<TSource> source, System.Linq.Expressions.Expression<Func<TSource,TKey>> keySelector, System.Collections.Generic.IComparer<TKey>? comparer);
static member ThenBy : System.Linq.IOrderedQueryable<'Source> * System.Linq.Expressions.Expression<Func<'Source, 'Key>> * System.Collections.Generic.IComparer<'Key> -> System.Linq.IOrderedQueryable<'Source>
<Extension()>
Public Function ThenBy(Of TSource, TKey) (source As IOrderedQueryable(Of TSource), keySelector As Expression(Of Func(Of TSource, TKey)), comparer As IComparer(Of TKey)) As IOrderedQueryable(Of TSource)

类型参数

TSource

source 的元素类型。The type of the elements of source.

TKey

keySelector 表示的函数返回的键类型。The type of the key returned by the function represented by keySelector.

参数

source
IOrderedQueryable<TSource>

一个包含要排序的元素的 IOrderedQueryable<T>An IOrderedQueryable<T> that contains elements to sort.

keySelector
Expression<Func<TSource,TKey>>

用于从每个元素中提取键的函数。A function to extract a key from each element.

comparer
IComparer<TKey>

用于比较键的 IComparer<T>An IComparer<T> to compare keys.

返回

IOrderedQueryable<TSource>

一个 IOrderedQueryable<T>,将根据键对其元素排序。An IOrderedQueryable<T> whose elements are sorted according to a key.

例外

sourcekeySelectorcomparernullsource or keySelector or comparer is null.

注解

此方法至少具有一个类型为的参数, Expression<TDelegate> 其类型参数为类型之一 Func<T,TResult>This method has at least one parameter of type Expression<TDelegate> whose type argument is one of the Func<T,TResult> types. 对于这些参数,可以传入 lambda 表达式,并将其编译为 Expression<TDelegate>For these parameters, you can pass in a lambda expression and it will be compiled to an Expression<TDelegate>.

ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>, IComparer<TKey>)方法生成一个 MethodCallExpression ,它表示调用 ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>, IComparer<TKey>) 自身作为构造的泛型方法。The ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>, IComparer<TKey>) method generates a MethodCallExpression that represents calling ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>, IComparer<TKey>) itself as a constructed generic method. 然后,它将传递 MethodCallExpressionCreateQuery<TElement>(Expression) IQueryProvider 由参数的属性表示的的方法 Provider sourceIt then passes the MethodCallExpression to the CreateQuery<TElement>(Expression) method of the IQueryProvider represented by the Provider property of the source parameter. 调用的结果 CreateQuery<TElement>(Expression) 将强制转换为类型 IOrderedQueryable<T> ,并返回。The result of calling CreateQuery<TElement>(Expression) is cast to type IOrderedQueryable<T> and returned.

由于执行表示调用的表达式树而发生的查询行为 ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>, IComparer<TKey>) 取决于参数类型的实现 sourceThe query behavior that occurs as a result of executing an expression tree that represents calling ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>, IComparer<TKey>) depends on the implementation of the type of the source parameter. 预期的行为是根据 source 通过 keySelector 对的每个元素调用而获得的键来执行的元素的次要排序 sourceThe expected behavior is that it performs a secondary sort of the elements of source based on the key obtained by invoking keySelector on each element of source. 所有以前建立的排序顺序都将保留。All previously established sort orders are preserved. comparer参数用于比较键值。The comparer parameter is used to compare key values.

ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>)

根据某个键按升序对序列中的元素执行后续排序。Performs a subsequent ordering of the elements in a sequence in ascending order according to a key.

public:
generic <typename TSource, typename TKey>
[System::Runtime::CompilerServices::Extension]
 static System::Linq::IOrderedQueryable<TSource> ^ ThenBy(System::Linq::IOrderedQueryable<TSource> ^ source, System::Linq::Expressions::Expression<Func<TSource, TKey> ^> ^ keySelector);
public static System.Linq.IOrderedQueryable<TSource> ThenBy<TSource,TKey> (this System.Linq.IOrderedQueryable<TSource> source, System.Linq.Expressions.Expression<Func<TSource,TKey>> keySelector);
static member ThenBy : System.Linq.IOrderedQueryable<'Source> * System.Linq.Expressions.Expression<Func<'Source, 'Key>> -> System.Linq.IOrderedQueryable<'Source>
<Extension()>
Public Function ThenBy(Of TSource, TKey) (source As IOrderedQueryable(Of TSource), keySelector As Expression(Of Func(Of TSource, TKey))) As IOrderedQueryable(Of TSource)

类型参数

TSource

source 的元素类型。The type of the elements of source.

TKey

keySelector 表示的函数返回的键类型。The type of the key returned by the function represented by keySelector.

参数

source
IOrderedQueryable<TSource>

一个包含要排序的元素的 IOrderedQueryable<T>An IOrderedQueryable<T> that contains elements to sort.

keySelector
Expression<Func<TSource,TKey>>

用于从每个元素中提取键的函数。A function to extract a key from each element.

返回

IOrderedQueryable<TSource>

一个 IOrderedQueryable<T>,将根据键对其元素排序。An IOrderedQueryable<T> whose elements are sorted according to a key.

例外

sourcekeySelectornullsource or keySelector is null.

示例

下面的代码示例演示如何使用 ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>) 对序列中的元素执行次要排序。The following code example demonstrates how to use ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>) to perform a secondary ordering of the elements in a sequence.

string[] fruits = { "grape", "passionfruit", "banana", "apple",
                      "orange", "raspberry", "mango", "blueberry" };

// Sort the strings first by their length and then
// alphabetically by passing the identity selector function.
IEnumerable<string> query =
    fruits.AsQueryable()
    .OrderBy(fruit => fruit.Length).ThenBy(fruit => fruit);

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

/*
    This code produces the following output:

    apple
    grape
    mango
    banana
    orange
    blueberry
    raspberry
    passionfruit
*/

Dim fruits() As String = _
    {"grape", "passionfruit", "banana", "mango", _
     "orange", "raspberry", "apple", "blueberry"}

' Sort the strings first by their length and then 
' alphabetically by passing the identity selector function.
Dim query = fruits.AsQueryable() _
    .OrderBy(Function(fruit) fruit.Length).ThenBy(Function(fruit) fruit)

' 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
'grape
'mango
'banana
'orange
'blueberry
'raspberry
'passionfruit

注解

此方法至少具有一个类型为的参数, Expression<TDelegate> 其类型参数为类型之一 Func<T,TResult>This method has at least one parameter of type Expression<TDelegate> whose type argument is one of the Func<T,TResult> types. 对于这些参数,可以传入 lambda 表达式,并将其编译为 Expression<TDelegate>For these parameters, you can pass in a lambda expression and it will be compiled to an Expression<TDelegate>.

ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>)方法生成一个 MethodCallExpression ,它表示调用 ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>) 自身作为构造的泛型方法。The ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>) method generates a MethodCallExpression that represents calling ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>) itself as a constructed generic method. 然后,它将传递 MethodCallExpressionCreateQuery<TElement>(Expression) IQueryProvider 由参数的属性表示的的方法 Provider sourceIt then passes the MethodCallExpression to the CreateQuery<TElement>(Expression) method of the IQueryProvider represented by the Provider property of the source parameter. 调用的结果 CreateQuery<TElement>(Expression) 将强制转换为类型 IOrderedQueryable<T> ,并返回。The result of calling CreateQuery<TElement>(Expression) is cast to type IOrderedQueryable<T> and returned.

由于执行表示调用的表达式树而发生的查询行为 ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>) 取决于参数类型的实现 sourceThe query behavior that occurs as a result of executing an expression tree that represents calling ThenBy<TSource,TKey>(IOrderedQueryable<TSource>, Expression<Func<TSource,TKey>>) depends on the implementation of the type of the source parameter. 预期的行为是根据 source 通过 keySelector 对的每个元素调用而获得的键来执行的元素的次要排序 sourceThe expected behavior is that it performs a secondary sort of the elements of source based on the key obtained by invoking keySelector on each element of source. 所有以前建立的排序顺序都将保留。All previously established sort orders are preserved.

适用于