Cypher Querie for compare two node attribute recurcively

Neo4j Graph Platform Cypher
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1

I try to find a right queries, at moment from the browser. I have a simple graph with node dependencies like parent -[:depend]-> child, each node have a modification_date attribute. From the last child I want to return all the "younger" parent in relation to their direct children, it's a real headache for me =].
Here a simple schema:

Screenshot_20181211_180054
Screenshot_20181211_180054.png1270×550 18.1 KB

I notice the comparison result under connections.

From the 'node10' the expected result should be : node09, node06, node08.

Thanks a lot for your help.

2

At moment I am stuck with this kind of queries:

match (A:Node)-[:DEPEND*..4]->(AC:Node {name:'node10'}) where A.modification_date>AC.modification_date return A

the problem is that it compare modification date with last node (node10) not with its direct child.

3

At the moment I can't think of a good query to use that would evaluate dynamically during traversal, but here's a query that will filter afterwards:

MATCH path = (AC:Node {name:10})<-[:DEPEND*..4]-(A:Node)
WITH A, [node in nodes(path) | node.modif_date] as dates
WHERE all(i in range(0, size(dates) - 2) WHERE dates[i] < dates[i + 1])
RETURN A
4

Thanks a lot !
Just I don't understand the - 2 in range(0, size(dates) - 2).

5

I understand the logi behind it, but in fact in my case is little bit more complicated :

Screenshot_20181212_171437
Screenshot_20181212_171437.png1309×793 29.3 KB

as we can see in this graph, the modification date is hold by a [:CURRENT] relationship attribute connect to a (M:Media) node.

With your previous answer I tried to find a result... but nothing, I still don't master well enough...

Your help will be marvelous !
Thanks

6

This one is a bit tricky, we need to use a nested pattern comprehension within the list comprehension (and make sure to project out the first element from that pattern comprehension):

MATCH path = (AC:Node {name:10})<-[:DEPEND*..4]-(A:Node)
WITH A, [node in nodes(path) | [(node)-[r:CURRENT]->() | r.modification_date][0]] as dates
WHERE all(i in range(0, size(dates) - 2) WHERE dates[i] < dates[i + 1])
RETURN A
7

Thanks a lot, Cypher is very powerful ! However my real case is still a bit tricky because r.modification_date is not always present ... Therefore I have some null values in dates lists : [null, 1544706574.1611595, null, 1543230042.1031768]. I tried to filter like that in the nested list but I still have those null :

[(node)-[r:CURRENT]->() where not r.modification_date is null | r.modification_date]
8

@andrew_bowman any idea why I keep those null event if they filter them ?
Thanks !!

9

Which version of Neo4j and APOC are you using? The WHERE r.modification_date IS NOT NULL should have worked here.

10

Neo4j Browser version: 3.2.5
Neo4j Server version: 3.4.5(community)

And honestly I have no idea about APOC version, where I can find this information.

11

You can use return apoc.version() to get the APOC version

12

Unknown function 'apoc.version' hum ... have I APOC ?

13

My mistake, I confused this question with a different one. You aren't using APOC Procedures here, it's not relevant to your question. Please disregard the request for the APOC version.

14

You may want to try upgrading your version, I know there was a bug affecting the planning of nested pattern comprehensions in 3.4.5 and below. Try upgrading to 3.4.10 (or 3.4.11) and see if you get expected results.

15

Hi again @andrew_bowman.
I upgraded neo4j 3.5.1, but unfortunately I still those null values.... what is weird that is :
[node in nodes(path) | [(node)-[r:CURRENT]->() where r.modification_date is null | r.modification_date][0]]
give me null only, which mean not is the problem... ?