Where $survey.user_identifier is from a collected_info_collection. It does not work. It fetches users if I remove the attribute filter so there must be something wrong with the filter.
What I want to accomplish is to display the users name (firstname, lastname) of the user who submitted a collected_info_collection.
The user_identifier attribute of an ezinformationcollection object return something like '12905d5437cf0f07165ede3c8d893fea'.
How do I use this to fetch the coresponding user object? I can't find any attributes in the user object that contain a value similar to that of ezinformationcollection.user_identifier.
But in your case, this won't do. The problem is that the remote_id of the user isn't a content class attribute in the user class, but a database field in the ezcontentobject table.
To filter on remote id you will need to write an extended attribute filter which filters on this field. The following link explains what it is and how it works.
I found out that the user_identifier attribute of an ezinformationcollection is actually a md5-sum of the string "user-" and the user_id of the user who submitted the information. So my filter would not have worked anyway.
eZ systems have made an extension that will translate this to user_id's. This will make it possible to filter ezinformationcollections based on the user_identifier attribute. It will appear under contributions very soon.