apoc.nodes.group seems unable to use DateTime as a grouping operator

[neo-technology-build-agent]

Issue by jgaskins
Saturday Mar 23, 2019 at 07:40 GMT
Originally opened as neo4j-contrib/neo4j-apoc-procedures#1129

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Expected Behavior (Mandatory)

Specifying min or max as a grouping operator on a datetime property groups

Actual Behavior (Mandatory)

Specifying min or max as a grouping operator on a datetime property results in an empty set.

I imagine this applies to other temporal types, as well, but I just happened to be using datetime when I discovered it.

How to Reproduce the Problem

Simple Dataset (where it's possibile)

First we create some nodes with datetime timestamps:

UNWIND range(1, 1000) AS minutes
CREATE (:Foo {
    created_at: datetime({ year: 2019, month: 3, day: 23 }) - duration({minutes: minutes})
})

Then we truncate those timestamps to some level of granularity we'll be grouping on:

MATCH (foo:Foo)
WHERE NOT exists(foo.created_at_hour)
SET foo.created_at_hour = datetime.truncate('hour', foo.created_at)

Steps (Mandatory)

1. Build the data set with the 2 Cypher queries above
2. Execute [Query 1] below with no grouping operators, data is returned
3. Execute [Query 2] below with a grouping operator specified for one of the datetime properties, no data is returned

[Query 1]

CALL apoc.nodes.group(['Foo'], ['created_at_hour'], [{}]) YIELD node
RETURN node

[Query 2]

CALL apoc.nodes.group(['Foo'], ['created_at_hour'], [{ created_at: 'min' }]) YIELD node
RETURN node

Screenshots (where it's possibile)

Specifications (Mandatory)

Currently used versions

Versions

• OS: Ubuntu 18.04
• Neo4j: 3.5.3 Community
• Neo4j-Apoc: 3.5.0.2

[neo-technology-build-agent]

Comment by jexp
Saturday Mar 23, 2019 at 07:45 GMT

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Good find, I guess it was because it was implemented before those datatypes were added.