Cypher Query - conditionally return a relationship - cypher

Question

I have been trying to figure out how to perform specific query for quite a while, and have been through several attempts to no avail. Below is an example to illustrate the problem:
There are 2 types of nodes, users and documents. Users can have a relationship type labeled collaborates_with, and can be related to documents as can_edit, created, or have no relationship.
Now what I would like to do is perform a query that will return all documents that fit a set of search criteria (say created within the last week), AND if the document was created by a collaborator of a specific user, return that relationship.
To fetch the documents and the creator of each document, the query is pretty straight forward:
MATCH (doc:document)<-[rel:created]-(u1:user)
WHERE doc.createddate > TIMESTAMP_FOR_ONE_WEEK_AGO
RETURN doc, u1
where TIMESTAMP_FOR_ONE_WEEK_AGO is just the unix timestamp corresponding to right now minus 7*24*60*60*1000.
The difficulty comes when trying to conditionally return the relationship with the current user.
I have played with CASE statements and OPTIONAL MATCH, but nothing seems to get what I'm looking for. One example of my attempts:
MATCH (doc:document)<-[rel:created]-(u1:user)
WHERE doc.createddate > TIMESTAMP_FOR_ONE_WEEK_AGO
WITH doc, u1
MATCH u1-[rel:collaborates_with]-(me:user)
WHERE me.username = MY_USERNAME
RETURN doc, rel
This, however, only returns the documents that have been created by one of my collaborators. Instead, I'd like it to return ALL of the documents fitting the search, and only return the relationship if it exists.
Has anyone been able to perform something like this?
NOTE: This question is similar, but not quite what I'm running into.

Answer 1

Optional Match should do it:
MATCH (doc:document)<-[rel:created]-(u1:user)
WHERE doc.createddate > TIMESTAMP_FOR_ONE_WEEK_AGO
WITH doc, u1 //find all docs that satisfy search conditions
OPTIONAL MATCH u1-[rel:collaborates_with]-(me:user) //optionally see if the creator collaborates with me
WHERE me.username = MY_USERNAME
RETURN doc, rel