How to programmatically restart a workflow

Question

I have a workflow linked to my list. Is there any programmatically way to select a list item and restart the associated workflow?

Something like:

SPListItem item = List.Items.GetById(1);
item.Workflows[GUID].Restart();

Is there any other way to get the same result?

Thank you very much!

Answer 1

SharePoint does not provide a method of restarting a workflow. You can however cancel a running workflow and start it again. A good example of canceling a running workflow can be found here: http://blog.brianfarnhill.com/2008/10/how-to-cancel-a-workflow-programmatically

The snippit of code below will start your workflow.

private static void StartWorkflow(SPListItem listItem, string workflowName)
{
    // Get the workflow by name that's associated with the list item
    SPWorkflowAssociation wfAssoc = listItem.ParentList.WorkflowAssociations.GetAssociationByName(workflowName, System.Globalization.CultureInfo.CurrentCulture);

    // Start the workflow
    listItem.Web.Site.WorkflowManager.StartWorkflow(listItem, wfAssoc, wfAssoc.AssociationData, true);
    listItem.Update();
}

Answer 2

The problem of the Bruce answer is that if the workflow is already started if throws an exption..

To fix this I modified his code, checking and removing the Workflow if there is!

   private static void RestartWorkflow(SPListItem listItem, string workflowName)
    {
        SPWorkflowAssociation wfAssoc = listItem.ParentList.WorkflowAssociations.GetAssociationByName(workflowName, System.Globalization.CultureInfo.CurrentCulture); 
        var WF = listItem.Workflows.Cast<SPWorkflow>().Where(X => X.ParentAssociation.Name == "Flusso di gestione delle informazioni"); //My wf name
        if (WF.Any()) //if there is remove
        {
            listItem.Web.Site.WorkflowManager.RemoveWorkflowFromListItem(WF.First());
        } //start
        listItem.Web.Site.WorkflowManager.StartWorkflow(listItem, wfAssoc, wfAssoc.AssociationData, true);
    }

Answer 3

If you use reusable Workflow. Change "...listItem.ParentList.WorkflowAssociations..." to "...listItem.ContentType.WorkflowAssociations..."