SPListItem.SystemUpdate updates SPListItem.File.ModifiedBy

Question

As can be seen from the debug image when I call SystemUpdate(false) of a SPItem, that SPItem's File object's ModifiedBy attribute changes to "SHAREPOINT\system". Sorry, it's a bit weird way to present it :). 'destinationFile' is an SPFile object. And since the object is not the same as the one in the Database after SystemUpdate call, it doesn't change on the debugger.

But why? It does as promised and it doesn't change the item's ModifiedBy etc.. But the SPFile object under it does change.

Anyway, how can I make sure both SPItem.ModifiedBy and SPFile.ModifiedBy don't change after I make some changes on SPItem.Properties?

Answer 1

The reason you're seeing this is because of references crossing each other.

You say destinationFile is an SPFile.

You call destinationFile.Item.SystemUpdate(false). Which is fine. You have to watch though, because SPFile.Item returns a reference to an SPListItem. If you call this twice, you get a different reference to the SPListItem. Therefore, if you call that, then try to access SPFile.Item.File You'll actually get a different reference to the SPListItem than you last checked, therefore it appears to the debugger that it's inconsistent.

Try this method (pseudo-coded):

SPFile destinationFile = ... (get the file reference somehow)
SPListItem destinationFileItem = destinationFile.Item;
destinationFileItem["someProperty"] = someValue;
// do some other stuff on the destinationFileItem object
destinationFileItem.SystemUpdate(false); // do not refer back to destinationFileItem after this point
// If you need to refer to the item again, get a new reference to store it in a variable. You can re-use destinationFileItem, though I'd set it to null first.

Answer 2

Hope this link can help you link

http://social.msdn.microsoft.com/Forums/en-US/sharepointdevelopment/thread/bea2b5e9-7a47-46bf-afd3-2c815bc9fb34