VariableEnumerator.Current 属性

定义

命名空间:

Microsoft.SqlServer.Dts.Runtime

程序集:

Microsoft.SqlServer.ManagedDTS.dll

从集合获取当前的 Variable 对象。

public:
 property Microsoft::SqlServer::Dts::Runtime::Variable ^ Current { Microsoft::SqlServer::Dts::Runtime::Variable ^ get(); };

public Microsoft.SqlServer.Dts.Runtime.Variable Current { get; }

member this.Current : Microsoft.SqlServer.Dts.Runtime.Variable

Public ReadOnly Property Current As Variable

属性值

Variable

当前的 Variable 对象。

示例

下面的代码示例将变量添加到包中。 代码示例使用各种方法查找变量并输出名称、值和命名空间。

using System;  
using System.Collections.Generic;  
using System.Text;  
using Microsoft.SqlServer.Dts.Runtime;  
namespace Adding_Variables  
{  
    class Program  
    {  
        static void Main(string[] args)  
        {  
            Application app = new Application();  
            // Load a sample package that contains a variable that sets the File Name.  
            Package pkg = app.LoadPackage(@"C:\Program Files\Microsoft SQL Server\100\Samples\Integration Services\Package Samples\CalculatedColumns Sample\CalculatedColumns\CalculatedColumns.dtsx", null);  
            Variables pkgVars = pkg.Variables;  
            Variable myVar = pkg.Variables.Add("myCustomVar", false, "User", "3");  

            // See if the variable is in the collection now.  
            Boolean hasMyVar = pkg.Variables.Contains("myCustomVar");  
            Console.WriteLine("The variable was found? {0}", hasMyVar);  

            // Loop over the collection using foreach keyword.  
            foreach (Variable pkgVar in pkgVars)  
            {  
                // Only print variables from the User namespace.  
                if (pkgVar.Namespace == "User")  
                {  
                Console.WriteLine("Variable: {0}, {1}", pkgVar.Name, pkgVar.Value.ToString());  
                 }  
            }  
            Console.WriteLine("---------------------------");  
            // Loop over the collection using the Enumerator.   
            VariableEnumerator myEnum = pkg.Variables.GetEnumerator();  
            int i = 0;  
            while ((myEnum.MoveNext()) && (myEnum.Current != null))  
                // Again only show User namespace variables.  
                if (myEnum.Current.Namespace == "User")  
                {                  
                    Console.WriteLine("[{0}] {1}, {2}", i++, myEnum.Current.Name, myEnum.Current.Namespace);  
                }  

            myEnum.Reset();  
            Console.WriteLine("---------------------------");  

            //Using the Item method syntax of [x], obtain the  
            // first entry in the collection.  
            myVar = pkgVars[0];  
            Console.WriteLine("The name and namespace of the first variable is: {0}, {1}", myVar.Name, myVar.Namespace);  
            String nameOfFirstItem = pkgVars[0].Name;  
            Console.WriteLine("The name of the first variable is: {0}", nameOfFirstItem);  
            //}  
        }  
    }  
}  

Imports System  
Imports System.Collections.Generic  
Imports System.Text  
Imports Microsoft.SqlServer.Dts.Runtime  

Namespace Adding_Variables  
    Class Program  
        Shared  Sub Main(ByVal args() As String)  
            Dim app As Application =  New Application()   
            ' Load a sample package that contains a variable that sets the File Name.  
            Dim pkg As Package =  app.LoadPackage("C:\Program Files\Microsoft SQL Server\100\Samples\Integration Services\Package Samples\CalculatedColumns Sample\CalculatedColumns\CalculatedColumns.dtsx",Nothing)   
            Dim pkgVars As Variables =  pkg.Variables   
            Dim myVar As Variable =  pkg.Variables.Add("myCustomVar",False,"User","3")   

            ' See if the variable is in the collection now.  
            Dim hasMyVar As Boolean =  pkg.Variables.Contains("myCustomVar")   
            Console.WriteLine("The variable was found? {0}", hasMyVar)  

            ' Loop over the collection using foreach keyword.  
            Dim pkgVar As Variable  
            For Each pkgVar In pkgVars  
                ' Only print variables from the User namespace.  
                If pkgVar.Namespace = "User" Then  
                Console.WriteLine("Variable: {0}, {1}", pkgVar.Name, pkgVar.Value.ToString())  
                End If  
            Next  
            Console.WriteLine("---------------------------")  
            ' Loop over the collection using the Enumerator.   
            Dim myEnum As VariableEnumerator =  pkg.Variables.GetEnumerator()   
            Dim i As Integer =  0   
            While (myEnum.MoveNext()) &&(myEnum.Current <> Nothing)  
                    Console.WriteLine("[{0}] {1}, {2}",i = Console.WriteLine("[{0}] {1}, {2}",i + 1  
            End While  

            myEnum.Reset()  
            Console.WriteLine("---------------------------")  

            'Using the Item method syntax of [x], obtain the  
            ' first entry in the collection.  
            myVar = pkgVars(0)  
            Console.WriteLine("The name and namespace of the first variable is: {0}, {1}", myVar.Name, myVar.Namespace)  
            Dim nameOfFirstItem As String =  pkgVars(0).Name   
            Console.WriteLine("The name of the first variable is: {0}", nameOfFirstItem)  
            '}  
        End Sub  
    End Class  
End Namespace  

示例输出：

找到了变量？ True

变量：myCustomVar，3

---------------------------

[0] myCustomVar， User

---------------------------

第一个变量的名称和命名空间为：CancelEvent、System

第一个变量的名称为：CancelEvent

注解

创建枚举器或调用 Reset 方法后， MoveNext 必须调用该方法才能将枚举器推进到集合的第一个元素，然后枚举器才能读取属性的值 Current ;否则， Current 未定义且引发异常。

Current如果最后一次调用返回MoveNextfalse，则也会引发异常，该调用指示集合的末尾。

Current不会移动枚举器的位置，并且连续调用以Current返回相同的对象，直到调用或MoveNextReset调用。

只要集合保持不变，枚举器就仍有效。 如果对集合进行了更改（例如添加、修改或删除元素），则枚举器将失效并变为不可恢复;因此，下一次调用 MoveNext 或 Reset 引发一个 InvalidOperationException。 但是，如果在调用 MoveNext 和 Current调用之间修改集合， Current 则返回它设置为的元素，即使枚举器已失效也是如此。