neo4j-graphql.js
A GraphQL to Cypher query execution layer for Neo4j and JavaScript GraphQL implementations.
neo4j-graphql-js is in active development. There are rough edges and APIs may change. Please file issues for any bugs that you find or feature requests.
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 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 { v1 as 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);
}
}
};
What is neo4j-graphql.js
A package to make it easier to use GraphQL and Neo4j together. neo4j-graphql.js translates GraphQL queries to a single Cypher query, eliminating the need to write queries in GraphQL resolvers and for batching queries. It also exposes the Cypher query language through GraphQL via the @cypher schema directive.
Goals
- Translate GraphQL queries to Cypher to simplify the process of writing GraphQL resolvers
- Allow for custom logic by overriding of any resolver function
- Work with
graphql-tools,graphql-js, andapollo-server - Support GraphQL servers that need to resolve data from multiple data services/databases
- Expose the power of Cypher through GraphQL via the
@cypherdirective
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
Contributing
See our detailed contribution guidelines.
Examples
See /examples
Documentation
Full docs can be found on GRANDstack.io/docs
Debugging and Tuning
You can log out the generated cypher statements with an environment variable:
DEBUG=neo4j-graphql-js node yourcode.js
This helps to debug and optimize your database statements. E.g. visit your Neo4J
browser console at http://localhost:7474/browser/ and paste the following:
:params :params { offset: 0, first: 12, filter: {}, cypherParams: { currentUserId: '42' } }
and now profile the generated query:
EXPLAIN MATCH (`post`:`Post`) WITH `post` ORDER BY post.createdAt DESC RETURN `post` { .id , .title } AS `post`
You can learn more by typing:
:help EXPLAIN
:help params