SharePoint 工作流:如何在不再次触发工作流的情况下更新项目 [英] SharePoint Workflow: how to update the item without triggering the workflow again

问题描述

我有一个 SharePoint 工作流程，它在项目更改时运行.工作流与外部 REST 服务进行通信.如果服务返回一个字符串，我想用该字符串更新字段值之一.不幸的是，一旦当前工作流终止，此更新将触发此项目的另一个工作流实例.我最终陷入了无限循环！

I have a SharePoint workflow which is running whenever the item changes. The workflow communicates with an external REST service. If the service returns a string, I want to update one of the field values with that string. Unfortunately, this update will trigger another instance of the workflow for this item once the current workflow terminates. I end up with an infinite loop!

如何防止这种情况发生? SPListItem 具有 Update()、UpdateOverwriteVersion() 和 SystemUpdate() 方法，但它们似乎都无法阻止触发后续工作流.

How I can prevent this from happening? SPListItem has Update(), UpdateOverwriteVersion(), and SystemUpdate() methods but none of them seem to prevent subsequent workflows from being triggered.

如果上次更新发生在特定时间跨度内，我可以检查项目的上次修改时间戳并终止工作流程，但我正在寻找更强大的解决方案.

I could inspect the last modified timestamp of the item and terminate the workflow if the last update happened within a certain timespan, but I am looking for a more robust solution.

推荐答案

您可以使用一些扩展方法来静默更新项目.

You could use some extension method to update item silently.

public static class SPListItemExtensions
{
/// <summary>
/// Provides ability to update list item without firing event receiver.
/// </summary>
/// <param name="item"></param>
/// <param name="doNotFireEvents">Disables firing event receiver while updating item.</param>
public static void Update(this SPListItem item, bool doNotFireEvents)
{
    SPItemEventReceiverHandling rh = new SPItemEventReceiverHandling();
    if (doNotFireEvents)
    {
        try
        {
            rh.DisableEventFiring();
            item.Update();
        }
        finally
        {
            rh.EnableEventFiring();
        }
    }
    else
    {
        item.Update();
    }
}

/// <summary>
/// Provides ability to update list item without firing event receiver.
/// </summary>
/// <param name="item"></param>
/// <param name="incrementListItemVersion"></param>
/// <param name="doNotFireEvents">Disables firing event receiver while updating item.</param>
public static void SystemUpdate(this SPListItem item, bool incrementListItemVersion, bool doNotFireEvents)
{
    SPItemEventReceiverHandling rh = new SPItemEventReceiverHandling();
    if (doNotFireEvents)
    {
        try
        {
            rh.DisableEventFiring();
            item.SystemUpdate(incrementListItemVersion);
        }
        finally
        {
            rh.EnableEventFiring();
        }
    }
    else
    {
        item.SystemUpdate(incrementListItemVersion);
    }
}

/// <summary>
/// Provides ability to update list item without firing event receiver.
/// </summary>
/// <param name="item"></param>
/// <param name="doNotFireEvents">Disables firing event receiver while updating item.</param>
public static void SystemUpdate(this SPListItem item, bool doNotFireEvents)
{
    SPItemEventReceiverHandling rh = new SPItemEventReceiverHandling();
    if (doNotFireEvents)
    {
        try
        {
            rh.DisableEventFiring();
            item.SystemUpdate();
        }
        finally
        {
            rh.EnableEventFiring();
        }
    }
    else
    {
        item.SystemUpdate();
    }
}

private class SPItemEventReceiverHandling : SPItemEventReceiver
{
    public SPItemEventReceiverHandling() { }

    new public void DisableEventFiring()
    {
        base.DisableEventFiring();
    }

    new public void EnableEventFiring()
    {
        base.EnableEventFiring();
    }


   }
}

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