Lookup field value is not getting set when using Client object model

Question

I have a document library (contact). Have created a custom list (workstatus). Have added column to contact library which is lookup of workstatus.

Below is my code using which i am setting the lookup column value. Unfortunately code runs fine (no exceptions) but when i check in SharePoint value is not set for the given column

FieldLookupValue lvworkstatus = new FieldLookupValue();
lvworkstatus.LookupId = workstatus;
item["crmworkstatus"] = lvworkstatus;
 item.Update();
context.Load(uploadFile);
context.ExecuteQuery();

Kindly let me know what is wrong / missing.

Answer 1

As Rob mentioned, the lookup value must be set by ID

$lookupfield = $l.Fields["lookupfield"] -as [Microsoft.SharePoint.SPFieldLookup];            
$lookuplist = $w.Lists[[Guid]$lookupfield.LookupList];            
$sourcefield =  $lookupfield.LookupField;            
$lookupitem = $lookuplist.Items[0];             
#-or-            
$lookupitem = $lookuplist.GetItemByUniqueId([Guid]"{fc71b84c-74d4-4f7c-9eed-fb7a5fbe24a6}")  
#-or-            
$lookupitem = $lookuplist.GetItemById(1)            
$lookupvalue = New-Object Microsoft.SharePoint.SPFieldLookupValue($lookupitem.ID,$lookupitem.ID.ToString());            
$i["lookupfield"] = $lookupvalue;            
$i.Update();

Here is an excellent reference for getting/setting various types in Sharepoint using Powershell:

http://social.technet.microsoft.com/wiki/contents/articles/20831.sharepoint-a-complete-guide-to-getting-and-setting-fields-using-powershell.aspx