Creating date nodes by looping through a start date and an end date

Neo4j Graph Platform Procedures & APOC
1

So I want to create 'n' number of nodes for 'n' number of days starting from a fixed start date (say 2020-01-01) to a fixed end date (current day).

How can I do this in a smart way (by using some kind of loop). I tried using UNWIND, but that seems to need me to create a list of all date first and then iterate through that. I want to avoid doing that kind of manual work.

Thanks!

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2

I got how to do this. I simply loaded a csv with all the dates in it.

However I would still love to know if there is a way to do it using ranges or something!

3

What do you mean by this? It's not manual work, and it is one of only two ways to efficiently handle lists. Avoiding UNWIND and collect is not a viable strategy in Neo4j, or any graph database.

That said, I'll admit that I struggled most with understanding those, than almost anything else, when I started learning Neo4j and Cypher. My personal favorite thread about it:
Cypher grammer, syntax, and documentation -- List, Collect, avg, etc are impenetrable to me - #5 by tony.chiboucas.

Your problem should be solved with creating, and unwinding, a list

Also, date, datetimes, and durations are similarly confusing. Here's some useful references for working with date and times:

WITH date("1985-01-01") AS startDate, date("1985-01-20") AS endDate
WITH startDate, endDate, range(0, duration.inDays(startDate, endDate).days) as dayDiffList
UNWIND dayDiffList AS dayDiff
WITH (startDate + duration({days: dayDiff})) as date RETURN date

...that will get you a list of dates, with which you can do whatever you want, like create nodes, and query or order results by date.

WITH date("1985-01-01") AS startDate, date("1985-01-20") AS endDate
WITH startDate, endDate, range(0, duration.inDays(startDate, endDate).days) as dayDiffList
UNWIND dayDiffList AS dayDiff
WITH (startDate + duration({days: dayDiff})) as dateVal
MERGE (:DateEntry {date: dateVal})

MATCH (d:DateEntry) 
WHERE d.date > date("1985-01-5")
RETURN d.date ORDER BY d.date DESC
1 Like
4

Wow that's great! Thanks for this, will try it out!