neo4j-multiple-database-graphql.md

Using Multiple Neo4j Databases

This section describes how to use multiple Neo4j databases with neo4j-graphql.js. Multiple active databases is a feature available in Neo4j v4.x

Neo4j supports multiple active databases. This feature is often used to support multi-tenancy use cases. Multiple databases can be used with neo4j-graphql.js by specifying a value in the GraphQL resolver context. If no value is specified for context.neo4jDatabase then the default database is used (as specified in neo4j.conf)

You can read more about managing and working with multiple databases in Neo4j in the manual here.

Specifying The Neo4j Database

The Neo4j database to be used is specified in the GraphQL resolver context object. The context object is passed to each resolver and neo4j-graphql.js at a minimum expects a Neo4j JavaScript driver instance under the driver key.

To specify the Neo4j database to be used, provide a value in the context object, under the key neo4jDatabase that evaluates to a string representing the desired database. If no value is provided then the default Neo4j database will be used.

For example, with Apollo Server, here we provide the database name sanmateo:

const neo4j = require('neo4j-driver');
const { ApolloServer } = require('apollo-server');

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

const server = new ApolloServer({
  schema,
  context: { driver, neo4jDatabase: 'sanmateo' }
});

server.listen(3004, '0.0.0.0').then(({ url }) => {
  console.log(`GraphQL API ready at ${url}`);
});

Specifying The Neo4j Database In A Request Header

We can also use a function to define the context object. This allows us to use a value from the request header or some middleware process to specify the Neo4j database.

Here we use the value of the request header x-database for the Neo4j database:

const neo4j = require('neo4j-driver');
const { ApolloServer } = require('apollo-server');

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

const server = new ApolloServer({
  schema,
  context: ({ req }) => {
    return { driver, neo4jDatabase: req.header['x-database'] };
  }
});

server.listen(3004, '0.0.0.0').then(({ url }) => {
  console.log(`GraphQL API ready at ${url}`);
});

Resources

• Multi-Tenant GraphQL With Neo4j 4.0 A Look At Using Neo4j 4.0 Multidatabase With neo4j-graphql.js