CODEWITHSUNDEEP
neo4jcyphergraph-databases
Mik378
Mik378

Reputation: 22171

Neo4j - Cypher / strange output when dealing with an array as node property

Using Cypher (Neo4j 2.1.2), it seems that array properties do not work well with aggregate functions.

For instance, I can have a RETURN clause like this:

RETURN meeting.title, count(participant) as number_part

Output: MyTitle 2

It well returns all the meetings's titles grouped by participants.

However, with an array as property rather than simple one like title, the output is strange:

 RETURN meeting.arrayProperty, count(participant) as number_part

Output: 

MyTitle [1,2,3]  1 
MyTitle [1,2,3]  1  //not grouped by ...

Better than text, here's a graphgist I made to explain the issue, the workaround I found and what I really expect.

Does anyone know the reason? (maybe obvious...)

Upvotes: 1

Views: 182

Answers (1)

Stefan Armbruster
Stefan Armbruster

Reputation: 39915

Just tried the following workaround: rebuild the array property as an collection:

RETURN extract(x in meeting.arrayProperty | x), count(participant) as number_part

Theory: the array property is handled as java native array whereas extract returns a collection (in Java sense). Comparing collections works based on comparing the elements whereas comparing a native array compares memory addresses which are different.

Upvotes: 2

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