Creating a Neo4j Date Tree that will work with py2neo

Question

I'm trying to build a date tree in my Neo4j database that will work with the calendar module in Nigel Small's py2neo library.

I used Mark Needham's starter code from here (http://java.dzone.com/articles/neo4j-cypher-creating-time), but that doesn't connect all of the Year nodes to a master calendar node, which is required for the py2neo library. (docs here: http://book.py2neo.org/en/latest/calendar/)

I've modified Mark's code to try and create a master node to connect all of the years like this:

CREATE (x:Calendar {name:'master'})
WITH range(2005, 2014) AS years, range(1,12) as months
FOREACH(year IN years | 
  CREATE (y:Year {year: year})
  MERGE (x)-[:YEAR]->(y)
  FOREACH(month IN months | 
    CREATE (m:Month {month: month})
    MERGE (y)-[:MONTH]->(m)
    FOREACH(day IN (CASE 
                      WHEN month IN [1,3,5,7,8,10,12] THEN range(1,31) 
                      WHEN month = 2 THEN 
                        CASE
                          WHEN year % 4 <> 0 THEN range(1,28)
                          WHEN year % 100 <> 0 THEN range(1,29)
                          WHEN year % 400 <> 0 THEN range(1,29)
                          ELSE range(1,28)
                        END
                      ELSE range(1,30)
                    END) |      
      CREATE (d:Day {day: day})
      MERGE (m)-[:DAY]->(d))))

What's happening is that there's a node (with Calendar label) that's getting created but no relationships attached to it, while there's a node (with no label) that's getting created and attached to each Year node.

I know this is probably a really easy fix, but I'm new to CYPHER and am really struggling to figure this out.

score 5 · Accepted Answer · answered Jul 14 '14 at 16:03

You forgot to transport the calendar master "x" through the WITH

CREATE (master:Calendar { name:'master' })
WITH range(2005,2014) AS years, range(1,12) AS months,master
FOREACH (year IN years | 
         CREATE (y:Year { year: year })
         MERGE (master)-[:YEAR]->(y)
         FOREACH (month IN months | 
                  CREATE (m:Month { month: month })
                  MERGE (y)-[:MONTH]->(m)
                  FOREACH (day IN (
                    CASE
                    WHEN month IN [1,3,5,7,8,10,12]
                    THEN range(1,31)
                    WHEN month = 2
                    THEN
                    CASE
                    WHEN year % 4 <> 0
                    THEN range(1,28)
                    WHEN year % 100 <> 0
                    THEN range(1,29)
                    WHEN year % 400 <> 0
                    THEN range(1,29)
                    ELSE range(1,28) END ELSE range(1,30) END )| 
                           CREATE (d:Day { day: day })
                           MERGE (m)-[:DAY]->(d))))

It took me a few minutes to see your change in line 2; I get it now. Thanks! — Jed Christiansen, Jul 14 '14 at 16:21

Creating a Neo4j Date Tree that will work with py2neo

1 Answers1