neo4j-graphql-js-quickstart.md

neo4j-graphql.js Quickstart

A GraphQL to Cypher query execution layer for Neo4j and JavaScript GraphQL implementations.

Installation and usage

Install

npm install --save neo4j-graphql-js

Usage

Start with GraphQL type definitions:

const typeDefs = `
type Movie {
    title: String
    year: Int
    imdbRating: Float
    genres: [Genre] @relation(name: "IN_GENRE", direction: OUT)
}
type Genre {
    name: String
    movies: [Movie] @relation(name: "IN_GENRE", direction: IN)
}
`;

Create an executable GraphQL schema with auto-generated resolvers for Query and Mutation types, ordering, pagination, and support for computed fields defined using the @cypher GraphQL schema directive:

import { makeAugmentedSchema } from 'neo4j-graphql-js';

const schema = makeAugmentedSchema({ typeDefs });

Create a neo4j-javascript-driver instance:

import neo4j from 'neo4j-driver';

const driver = neo4j.driver(
  'bolt://localhost:7687',
  neo4j.auth.basic('neo4j', 'letmein')
);

Use your favorite JavaScript GraphQL server implementation to serve your GraphQL schema, injecting the Neo4j driver instance into the context so your data can be resolved in Neo4j:

import { ApolloServer } from 'apollo-server';

const server = new ApolloServer({ schema, context: { driver } });

server.listen(3003, '0.0.0.0').then(({ url }) => {
  console.log(`GraphQL API ready at ${url}`);
});

If you don't want auto-generated resolvers, you can also call neo4jgraphql() in your GraphQL resolver. Your GraphQL query will be translated to Cypher and the query passed to Neo4j.

import { neo4jgraphql } from 'neo4j-graphql-js';

const resolvers = {
  Query: {
    Movie(object, params, ctx, resolveInfo) {
      return neo4jgraphql(object, params, ctx, resolveInfo);
    }
  }
};

Benefits

• Send a single query to the database
• No need to write queries for each resolver
• Exposes the power of the Cypher query language through GraphQL

Features

• Translate basic GraphQL queries to Cypher
• first and offset arguments for pagination
• @cypher schema directive for exposing Cypher through GraphQL
• Handle fragments
• Ordering
• Filtering
• Handle interface types
• Handle inline fragments
• Native database temporal types (Date, DateTime, LocalDateTime)
• Native Point database type