#Purpose : Script to Populate Workflow history Column for an Item from the hidden workflow history list.
 #Enviornmnets : SharePoint 2010, SharePoint 2013 (Change the Add-Type -Path to point to 15 folder).
 #Author : Isha Kapoor 

 Add-Type -Path "C:\Program Files\Common Files\microsoft shared\Web Server Extensions\14\ISAPI\Microsoft.SharePoint.Client.dll" 
 Add-Type -Path "C:\Program Files\Common Files\microsoft shared\Web Server Extensions\14\ISAPI\Microsoft.SharePoint.Client.Runtime.dll" 
 Add-Type -Path "C:\Program Files\Common Files\microsoft shared\Web Server Extensions\14\ISAPI\Microsoft.Online.SharePoint.Client.Tenant.dll" 


$BatchSize="1000"


# Add path for your SP2010 site. 

$siteUrl = "{yoursiteurl}"

$ctx = New-Object Microsoft.SharePoint.Client.ClientContext($siteUrl)

$ctx.Load($ctx.Web.Lists)
$ctx.Load($ctx.Web)

 try
 {
   $ctx.ExecuteQuery()
     
   $_lists = $ctx.Web.Lists

   #Get Items from the Document Library. Change the library name below if running on another library. 

   $_list = $_lists.GetByTitle("Documents")
     

   $Query = New-Object Microsoft.SharePoint.Client.CamlQuery
   $Query.ViewXml = @"
    <View Scope='RecursiveAll'>
        <Query>
            <OrderBy><FieldRef Name='ID' Ascending='TRUE'/></OrderBy>
        </Query>
        <RowLimit Paged="TRUE">$BatchSize</RowLimit>
    </View>
"@


  
  Do 
  {

    $items = $_list.GetItems($Query);

    $ctx.Load($_list);

    $ctx.Load($items);

    $ctx.ExecuteQuery()
   

    Write-Host "Retreving Number of Items : " $items.Count + "from Source List with Id : " + $_list.Id -foregroundcolor green;

    foreach($listItem in $items)
	{

     
     #Run a query to get WF items related to the above List ID and Item Id

     $_WFlist = $_lists.GetByTitle("Workflow history");

     $_listID = $_list.Id.ToString().TrimEnd();
     $ItemID = $listItem["ID"];

      Write-Host "Retriving Workflow History for Item ID : " $ItemID;
 

     $Query1 = New-Object Microsoft.SharePoint.Client.CamlQuery
   
   $Query1.ViewXml = @"
    <View Scope='RecursiveAll'>
        <Query>
            <Where>
             <And>
                   <Eq><FieldRef Name='List' /><Value Type='Text'>$_listID</Value></Eq>
                   <Eq><FieldRef Name='Item' /><Value Type='Integer'>$ItemID</Value></Eq>   
             </And>
             </Where>
            <OrderBy><FieldRef Name='List' decending='TRUE'/></OrderBy>
        </Query>
     </View>
"@


              
   $wfitems = $_WFlist.GetItems($Query1)

   #Load the Workflow list items in current context

   $ctx.Load($_WFlist);

   $ctx.Load($wfitems);

     
   $ctx.ExecuteQuery()
   
   Write-Host "Retrived Number of Matching Items (by List Id) from WF history list : " $wfitems.Count -foregroundcolor green


   Write-Host "Generating Workflow History Array";

   $WFvariable = "";

   foreach($WflistItem in $wfitems)
   {
        Write-Host "Updating value for Workflow History field";
 	$WFvariable = "OutCome = " $WflistItem["Outcome"] + "Desciption : " +  $WflistItem["Description"] + "\n";

   }

      #Updating Original Item with WF history

      $listItem["WorkflowHistory"] = " ";
       
      $listItem["WorkflowHistory"] = $WFvariable;
        
      $listItem.Update();

      $Ctx.ExecuteQuery();

      Write-Host "Item Updated."
    
     }  
   
   $Query.ListItemCollectionPosition = $items.ListItemCollectionPosition

   }
      
    While($Query.ListItemCollectionPosition -ne $null)
 

  }
        catch
        {
            $ErrorMessage = $_.Exception.Message
         write-host "Error : " $ErrorMessage -foregroundcolor red
        }