Add a workflow to a SharePoint list in all sites of a site collection using PowerShell

This script sets up a function to add a workflow association to a specifically named list or document library in all sites of a site collection. For example, adding a workflow to the “Pages” document library in all publishing sites. You use the function by first running the script and then calling it using the following command:

AddWorkflowToLibraries -SiteCollection http://portal -ListName Pages -WfName "Collect Feedback - SharePoint 2010" -WfAssociationName "Collect Feedback"

The example above adds the out-of-box SharePoint 2010 Collect Feedback workflow to the Pages library in each site of the http://portal site collection, calling it “Collect Feedback”. If a site does not have a Pages library (e.g., a Team site), the script will pass over it and continue on to the next site. The script will also continue to the next site if the workflow already exists in the list and I have added an optional delete section (commented out in the script below) which you can use to delete a workflow associated with each list – this will allow you to bulk delete workflow associations before creating new ones.

Run this script first before typing the AddWorkflowToLibraries command above:

function AddWorkflowToLibraries ($SiteCollection, $ListName, $WfName, $WfAssociationName)
{

    #Get site object and create blank guid to store workflow template ID
    $site = Get-SPSite $SiteCollection
    [Guid]$wfTemplateId = New-Object Guid

    #Step through each web in site collection
    $site | Get-SPWeb -limit all | ForEach-Object {

        #Do the following if a list exists with the name specified by the user - e.g., Pages
        if ($_.Lists[$ListName]) {

            write-host $_.Title"has a list called"$ListName -ForegroundColor green

            $list = $_.Lists[$ListName]
            #Go through each workflow installed in the site to find the correct ID           
            foreach ($wfTemplate in $_.WorkflowTemplates) {
                if ($wfTemplate.Name -eq $WfName) {
                $wfTemplateId = $wfTemplate.Id
                }
            }
            #Set up the template from the ID found
            $wfTemplate = $_.WorkflowTemplates[$wfTemplateId]
            #Check if the site already has a workflow history list - if not, create it
            if(!$_.Lists["Workflow History"])
            {
                $_.Lists.Add("Workflow History", "A system library used to store workflow history information that is created in this site.  It is created by the Publishing feature.",
                "WorkflowHistory", "00BFEA71-4EA5-48D4-A4AD-305CF7030140", 140, "100")
                if (!$_.Features["00BFEA71-4EA5-48D4-A4AD-305CF7030140"]) {
                    Enable-SPFeature -Identity WorkflowHistoryList -Url $_.Url
                }
                $wfHistory = $_.Lists["Workflow History"]
                $wfHistory.Hidden = $true
                $wfHistory.Update()
            }
            else
            {
                $wfHistory = $_.Lists["Workflow History"]
            }
            #Check if the site already has a workflow tasks list - if not, create it
            if(!$_.Lists["Workflow Tasks"])
            {
                $_.Lists.Add("Workflow Tasks", "This system library was created by the Publishing feature to store workflow tasks that are created in this site.", "WorkflowTasks", "BF611337-1591-49f4-BF42-CE7BE53852D8", 107, "100")
            }
            $wfTasks = $_.Lists["Workflow Tasks"]
            #Set up workflow association (extra associated data can be added if you have it)
            $wfAssociation = [Microsoft.SharePoint.Workflow.SPWorkflowAssociation]::CreateListAssociation($wfTemplate, $WfAssociationName, $wfTasks, $wfhistory)
            #Check to see if the association has already been added to the list
            [guid]$wfId = New-Object Guid
            [bool]$wfFound = $false
            foreach ($wf in $list.WorkflowAssociations) {
                if ($wf.Name -eq $wfAssociation.Name) {
                    $wfId = $wf.Id
                    write-host "Workflow"$wf.Name"already exists on"$list.Title"list in site"$_.Title -ForegroundColor green
                    $wfFound = $true
                }
            }
            #If association is already there, ignore the add (and optionally delete it)
            if ($wfFound -eq $true) {
                #Command to remove existing workflow from list before adding new one, if required
                #$list.WorkflowAssociations.Remove($wfId)
                #write-host "Removed workflow"$wfAssociation.Name"from"$list.Title"in site"$_.Title -ForegroundColor green
            }
            #else, add it to the workflow association to the list
            else
            {
                $list.WorkflowAssociations.Add($wfAssociation)
                write-host "Added workflow"$wfAssociation.Name"to"$list.Title"in site"$_.Title -ForegroundColor green
            }
        }
        #Report if the site does not have the list specified by the user
        else {
            write-host $_.Title"does not have a list called"$listName -ForegroundColor green
        }
    }
    #Dispose of Site object
    $site.Dispose()
}

Another thing to note here are the names of the history and task lists associated with the workflow. I have gone with “Workflow History” and “Workflow Tasks” but you can change these as required. The script will create these lists if they do not exist already on a site (e.g., when a Publishing site template is used without the approval workflow).