Setting author field in SPListItem will not be saved

Question

I am trying to copy SPListItem (with file) from one site collection to another. I do this by creating a file as follows:

var archiveFile = newsArchive.Lists[listName].RootFolder.Files.Add(originalItem.File.Name, originalItem.File.OpenBinary());
var archiveItem = archiveFile.Item;

using the utility that I wrote, I then set all the field values ​​of the new element to match the original element in this way

Utilities.PopulateListItemMetadata(....)

The fact is that this is not stored in the Author field.

I tried to customize the Author field explicitly for all possible purposes, for example:

string userName = originalItem.GetUser("Created by").LoginName;
SPUser user = newsArchive.SiteUsers[userName];
archiveItem["Author"] = user.ID + ";#" + user.LoginName;
archiveItem.Update();

And so

string userName = originalItem.GetUser("Created by").LoginName;
SPUser user = newsArchive.SiteUsers[userName];
archiveItem["Author"] = user;
archiveItem.Update();

But as soon as the SPListItem.Update () method was called, the archiveItem ["Author"] field returned to sharepoint \ system. I'm a little at a loss, this should work.

PS method SPListItem.GetUser is an extension method

PPS Code starts from timer job ...

: , , , , . , web.EnsureUser( ) . ?!

Answer 1

,

SPFieldUserValue val = new SPFieldUserValue(newsArchive, user.ID, user.Name);
archiveItem["Author"] = val; 
archiveItem.SystemUpdate(false);

!

Answer 2

. .

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Edit

:

SPUser user = newsArchive.SiteUsers[userName];

:

SPUser user = newsArchive.EnsureUser(userName);

, , . SiteUsers - . SharePoint , , , .