Query with optional match

[lx2pwnd]

I'm using neovis.js in my web app to connect with neo4j db where there are a node (:user) and some nodes (:Friend)
For each nodes (:Friend) there are a relationship [:FRIEND] between they and the (:user) like in the screen below

Some nodes (:Friend) are connected by a relationship [s:TAGGED_TOGETHER] like in the screen below, which have an attribute s.tagged_together

Every nodes (n:Friend) have an attribute n.timestamp.

My goal is to return every relationship [:TAGGED_TOGETHER] greater then a specific value and every relationship [:FRIEND] in a specific range of time

I write this query

MATCH x=(:fbUser)-[:FRIEND]-(f) 
OPTIONAL MATCH y=(f)-[s:TAGGED_TOGETHER]-(d:Friend) 
WITH x,f,y,s,d, case d when null then [] else [1] end as iterList  
WHERE 
(f.timestamp>'2018/01/01'  AND f.timestamp< '2019/01/01' ) AND
ALL (x in iterList WHERE 
s.tagged_together>=0) 
RETURN x,y

But in this way the query return for each node (n:Friend)all the [:TAGGED_TOGETHER] relationship.
So, I thinked to modify the query as follow:

MATCH x=(:fbUser)-[:FRIEND]-(f) 
OPTIONAL MATCH y=(f)-[s:TAGGED_TOGETHER]-(d:Friend) 
WITH x,f,y,s,d, case d when null then [] else [1] end as iterList  
WHERE 
(f.timestamp>'2018/01/01'  AND f.timestamp< '2019/01/01' ) AND
ALL (x in iterList WHERE 
s.tagged_together>=0 AND d.timestamp>'2018/01/01'  AND d.timestamp< '2019/01/01' ) 
RETURN x,y

But i think that it's incorrect because not all the node (:Friend) are connected with the (:user) although they have the timestamp in the range of time specified

How can I correct the query ?

[ameyasoft · Accepted solution]

Try this:

MATCH (a:User)-[:FRIEND]-(f:Friend) 
WHERE f.timestamp >= '2018/01/01' and f.timestamp <= '2019/01/01'
OPTIONAL MATCH (f)-[:TAGGED_TOGETHER]->(d:Friend)
RETURN a, f, d

[lx2pwnd]

I add the where clause under the optional match and it works. Thanks