Despite the “Graph” in the name, GraphQL is mostly used to query relational databases or object models. But it is really well suited to querying graph databases too. In this talk, I’ll demonstrate how I implemented a GraphQL endpoint for the Neo4j graph database and how you would use it in your app.

2. neo4j.com/developer

3. Property Graph Model
CAR
name: “Dan”
born: May 29, 1970
twitter: “@dan”
name: “Ann”
born: Dec 5, 1975
since:
Jan 10, 2011
brand: “Volvo”
model: “V70”
LOVES
LOVES
LIVES WITH
PERSON PERSON

4. Whiteboard Model Is the Physical Model

5. Cypher: Powerful & Expressive Graph Query Language
MATCH (:Person { name:“Dan”} ) -[:LOVES]-> (:Person { name:“Ann”} )
LOVES
Dan Ann
LABEL PROPERTY
NODE NODE
LABEL PROPERTY

7. Use Neo4j like a regular
backing database
https://launchpad.graphql.com/3wzp7qnjv

8. Or ... turn Neo4j into
a native GraphQL backend

9. 1. take GraphQL query
2. transform to Cypher
3. execute against graph
4. return results

10. Based on ... what?
Schema!
Which schema?

11. Neo4j is schema-free, so:
[x] Use GraphQL Schema

12. Neo4j is
open source
& extensible
Let‘s build an extension

13. How hard can it be?

14. Transform + project
Query / Results
Thank you!

15. Introducing:
neo4j-graphql
What‘s in the box?

16. Basics
Endpoint with basic auth
host:port/graphql
POST schema file
run queries with params
project results

17. Cool Features
generate & run single graph query
auto generated mutations for types
first, offset, orderBy, @relation
lookup by any field
fragments, unlimited nesting

18. Power Up: @cypher
computed fields
custom mutations & queries
parameter support

19. Cool!
How can I use it?

20. npm install -g neo4j-graphql-cli
neo4j-graphql [my.schema]

24. movies.schema

27. add superpower
type Actor {
totalMovies:Int @cypher(statement:
"RETURN size( (this)-[:ACTED_IN]->(:Movie) ) as total")
...
type Movie {
similar:[Movie] @cypher(statement:
"MATCH (this)-->(:Genre)<--(o:Movie) RETURN o LIMIT 10")
...
type QueryType {
topRatedMovies(score:Int) [Movie] @cypher(statement:
"MATCH (m:Movie)<-[r:RATED]-(:User) WHERE r.score > $score
RETURN m, avg(r.score) as score
ORDER BY score DESC LIMIT 10")

28. github.com/neo4j-graphql

29. graphql.communitygraph.org