Hello,
I'm new to Neo4j Cypher, trying to understand all the basics of syntax.
Found this code (source page here)
MATCH (p:Person) WITH collect(distinct p.country) as countries
WITH [cName IN countries | apoc.create.vNode(['Country'],{name:cName})] as countryNodes
WITH apoc.map.groupBy(countryNodes,'name') as countries
MATCH (p1:Person)-[:KNOWS]->(p2:Person)
WITH p1.country as cFrom, p2.country as cTo, count(*) as count, countries
RETURN countries[cFrom] as from, countries[cTo] as to, apoc.create.vRelationship(countries[cFrom],'KNOWS',{count:count},countries[cTo]) as rel;
Can't figure out how line 2 of the code works.
If I split it into blocks, it starts with the WITH keyword, and ends with a variable name:
WITH [] as countryNodes
Alright, so far so good. Variable countryNodes gets assigned some value that's coming from the square brackets.
But what do those square brackets do?
[cName IN countries | apoc.create.vNode(['Country'],{name:cName})]
I cannot find any manual page that suggests a syntax like this:
[ expression | expression ]
I would appreciate if someone could explain this and also provide some hints to documentation (if that is a documented syntax).
