Artikel
05/23/2011

TaskHost.GetExpression Method

Returns the expression for the specified property. Null means no expression is assigned.

Namespace: Microsoft.SqlServer.Dts.Runtime
Assembly: Microsoft.SqlServer.ManagedDTS (in Microsoft.SqlServer.ManagedDTS.dll)

Syntax

'Declaration
Public Function GetExpression ( _
    propertyName As String _
) As String
'Usage
Dim instance As TaskHost
Dim propertyName As String
Dim returnValue As String

returnValue = instance.GetExpression(propertyName)

public string GetExpression(
    string propertyName
)

public:
virtual String^ GetExpression(
    String^ propertyName
) sealed

abstract GetExpression : 
        propertyName:string -> string 
override GetExpression : 
        propertyName:string -> string

public final function GetExpression(
    propertyName : String
) : String

Parameters

propertyName
Type: System.String
The name of the property whose expression you want to see.

Return Value

Type: System.String
A String that contains the expression used to evaluate the property.

Implements

IDTSPropertiesProvider.GetExpression(String)

Remarks

The propertyName can be any property available on the object.

Examples

The following code example shows how to use the SetExpression and GetExpression methods of the TaskHost. For this code example, the hosted task is the BulkInsertTask.

using System;
using System.Collections.Generic;
using System.Text;
using Microsoft.SqlServer.Dts.Runtime;
using Microsoft.SqlServer.Dts.Tasks.BulkInsertTask;


namespace Microsoft.SqlServer.SSIS.Sample
{
    class Program
        {
        static void Main(string[] args)
        {
            Package pkg = new Package();
            TaskHost th = (TaskHost)pkg.Executables.Add("STOCK:BulkInsertTask");

            // View information about the CheckConstraints property
            // before setting it using the SetExpression method.
            Boolean checkConstraint = (Boolean)th.Properties["CheckConstraints"].GetValue(th);
            Console.WriteLine("Original value of CheckConstraints: {0}", checkConstraint);

            // Use SetExpression to set the value to true.
            String myTrueString = "true";
            th.Properties["CheckConstraints"].SetExpression(th, myTrueString);

            // Validate the package to set the expression onto the property.
            DTSExecResult valResult = pkg.Validate(null, null, null, null);

            // Retrieve the new value and the expression.
            checkConstraint = (Boolean)th.Properties["CheckConstraints"].GetValue(th);
            String myExpression = th.Properties["CheckConstraints"].GetExpression(th);
            Console.WriteLine("New value of CheckConstraints: {0}", checkConstraint);
            Console.WriteLine("Expression for CheckConstraints: {0}", myExpression);
        }
    }
}

Sample Output:

Original value of CheckConstraints: False

New value of CheckConstraints: True

Expression for CheckConstraints: true

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