How to disable list event firing from SharePoint 2013 workflow?

Question

I have a list with an ItemUpdating event receiver that blocks all item updates.

I have a workflow where I want to update an item in this list.

Is there any way to disable the event receiver from the SP2013 workflow, perform the update, then re-enable the event receiver?

Or, if there was a way to check whether it is a user or a workflow that is making the update, I could add a condition in the event receiver and only allow updates from workflows.

Answer 1

The easiest workaround is to add a hidden field into the list. And let the workflow update a predefined value into that field.

In the event receiver check the hidden field is equal to predefined value. Then that means it's been invoked from the workflow. Then reset the field to empty so the next update can be validated using the same field.

Answer 2

Create a class that derives from SPItemEventReceiver and IDisposable. Example:

public class EventReceiverScope : SPItemEventReceiver, IDisposable
{
    private bool mOriginal = false;

    public EventReceiverScope(bool enabled)
    {
        this.mOriginal = this.EventFiringEnabled;
        this.EventFiringEnabled = enabled;
    }

    public void Dispose()
    {
        this.EventFiringEnabled = this.mOriginal;
    }
}

Then call the above class like this in the Workflow code:

using (EventReceiverScope scope = new EventReceiverScope(false))
{
    //WF code here to perform update
}

Answer 3

In the end, the event receiver looked like this:

    public override void ItemUpdating(SPItemEventProperties properties)
    {
        base.ItemUpdating(properties);

        var fromWorkflow = properties.AfterProperties["hFromWorkflow"];

        if (fromWorkflow != null)
        {
            if (fromWorkflow.ToString() != "y")
            {                  
                properties.Status = SPEventReceiverStatus.CancelWithError;
                properties.ErrorMessage = "A message";
            }
            else
                properties.AfterProperties["hFromWorkflow"] = "n";
        }
    }