SharePoint Documents Library - Change "Document Created By" field

I have a code that changes the username in various SharePoint lists, mostly b开发者_C百科y the "Author" column. It all works fine on normal lists, but it doesn't seem to work on the "Shared Documents" list which is a document library.

Whether I change the username in "Created By" or "Document Created By", the change doesn't seem to take effect. The item.Update command doesn't throw any exception, but it clearly doesn't update the field(s).

What can I do if I want to change this field through code?

Thanks

I found a workaround for my problem.

Only the last field I'm trying to update is being "overwritten".

So, while the following code won't work:

item["Author"] = 22;

item.SystemUpdate();

This one will do:

item["Author"] = 22;

item["Modified By"] = item["Modified By"]; //Or any other field 

item.SystemUpdate();

Maybe this could help How to change the value of "Created By"...

Pay attention on AllowUnsafeUpdates property.