CODEWITHSUNDEEP
neo4jcypher
shameem sattar
shameem sattar

Reputation: 11

Neo4J query to join multiple matches to return results

When I run the query below query 1 is producing result returning all categories label for a document for all documents. Note a document can have multiple categories hence collecting them in on go.

START doc = node:entities(type = "document-link")
MATCH  category-[:category]-doc<-[:`document-link`]-id
RETURN 
  doc.title    as title,
  COLLECT(COALESCE(category.category, "")) as categories

query 2 is producing result returning language of the document for all documents. A document can have only one language type. 

START  doc = node:entities(type = "document-link")
MATCH  lan-[:language]-doc<-[:`document-link`]-id
RETURN 
  doc.title    as title,
  lan.language as language

query 3 which is join of 1 and 2 is producing empty result. Can someone highlight what I am doing wrong?

START  doc = node:entities(type = "document-link")
MATCH  category-[:category]-lan-[:language]-doc<-[:`document-link`]-id
RETURN 
doc.title    as title,
lan.language as language,
COLLECT(COALESCE(category.category, "")) as categories

Upvotes: 1

Views: 1293

Answers (1)

David ten Hove
David ten Hove

Reputation: 2826

In your third query you match on a relation between category and a language, which you don't do in your first 2 queries. How about this:

START  doc = node:entities(type = "document-link")
MATCH category-[:category]-doc<-[:`document-link`]-id
MATCH doc-[:language]-lan
RETURN 
doc.title    as title,
lan.language as language,
COLLECT(COALESCE(category.category, "")) as categories

Upvotes: 1

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