CODEWITHSUNDEEP
neo4jcypher
user3115696
user3115696

Reputation: 311

Nested has_many relationships in cypher

I have a nested has_many relationship that I'm trying to map to a json result.

The following example from the blog shows the kind of thing I want to do, except it's not nested

 MATCH (a:Person { name: "Andres" })-[:FATHER_OF]->(child)
  RETURN 
  {name:a.name, kids:collect(child.name)} as document

What I want instead is something like this

 MATCH (a:Person { name: "Andres" })-[:FATHER_OF]->(child)-[:has_read]->(book)-[:has_chapter]->(chapter)
  RETURN 
  {name:a.name, kids:collect({"name":child.name, has_read:collect(book)})} as document

In this case I would like to return a json object of a structure like this:

{
  "name": "Andres"
  "kids": [
           {
             "name":"Bob"
             "has_read": [
                           {
                            "name":"Lord of the Rings",
                            "chapters": ["chapter1","chapter2","chapter3"]
                           },
                           {
                            "name":"The Hobbit",
                            "chapters": ["An unexpected party","Roast mutton"]
                           }
                         ]
           },
           {
             "name":"George"
             "has_read": [
                           {
                            "name":"Lord of the Rings",
                            "chapters": ["chapter1","chapter2","chapter3"]
                           },
                           {
                            "name":"Silmarillion",
                            "chapters": ["chapter1","chapter2"]
                           }
                         ]
           }

          ]
}

Upvotes: 3

Views: 1460

Answers (1)

Michael Hunger
Michael Hunger

Reputation: 41706

Can you try:

if you keep the match to the chapter you will need distinct collect(distinct book.title) otherwise not.

MATCH (a:Person { name: "Andres" })-[:FATHER_OF]->(child),
      (child)-[:has_read]->(book)-[:has_chapter]->(chapter)
WITH a,child,collect(distinct book.title) as books
RETURN 
  {name:a.name, 
   kids:collect({name:child.name, 
                 has_read:books})} as document

Oh and if you want to include the chapters in the results too, then just add another with :)

MATCH (a:Person { name: "Andres" })-[:FATHER_OF]->(child),
      (child)-[:has_read]->(book)-[:has_chapter]->(chapter)
WITH a,child, {title: book.title, chapters: collect(chapter.title)} as book_doc
WITH a,child, collect(book_doc) as books
RETURN 
  {name:a.name, 
   kids:collect({name:child.name, 
                 has_read:books})} as document

see: http://console.neo4j.org/r/kua2pi

Upvotes: 6

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