GraphQL quick start

Run Memgraph

If you’re new to Memgraph or you’re in a developing stage, we recommend using the Memgraph Platform. Besides the database, it also includes all the tools you might need to analyze your data, such as command-line interface mgconsole, web interface Memgraph Lab and a complete set of algorithms within a MAGE library.

Ensure Docker is running in the background. Depending on your operating system, execute the appropriate command in the console:

For Linux and macOS:

curl https://install.memgraph.com | sh

For Windows:

iwr https://windows.memgraph.com | iex

The command above will start Memgraph Platform, which includes Memgraph database, Memgraph Lab and Memgraph MAGE. Memgraph uses Bolt protocol to communicate with the client using the exposed 7687 port. Memgraph Lab is a web application you can use to visualize the data. It’s accessible at http://localhost:3000 if Memgraph Platform is running correctly. The 7444 port enables Memgraph Lab to access and preview the logs, which is why both of these ports need to be exposed.

For more information visit the getting started guide on how to run Memgraph with Docker.

Create a work directory

Next, create a directory for your project and position yourself in it:

mkdir graphql-example
cd graphql-example

Initialize the Node.js project

Initialize the project using the following code:

npm init es6 --yes

Setup the Neo4j GraphQL Library

Install the library, its dependencies, and a GraphQL server (such as Apollo Server) by running the following command:

npm install @neo4j/graphql@7.2.0 graphql neo4j-driver @apollo/server

Create the Schema

GraphQL APIs need to be aware of the shape of the data they are working with, which is abstracted into the concept of GraphQL schemas. This must be explicitly specified in the Node.js application file. In terms of a property graph, the schema must contain the labels and properties of nodes and relationships. (Whilst the Neo4j GraphQL Library has support for automatic graph introspection, Memgraph currently does not support this feature.)

More information on defining a GraphQL schema can be found in the GraphQL documentation.

Given the following dataset:

CREATE (u1:User {id: "user1", name: "Alice"})
CREATE (u2:User {id: "user2", name: "Bob"})
CREATE (p1:Post {id: "post1", content: "Alice's first post!"})
CREATE (p2:Post {id: "post2", content: "Bob's great idea."})
CREATE (p3:Post {id: "post3", content: "Another thought from Alice."})
CREATE (u1)-[:HAS_POST]->(p1)
CREATE (u2)-[:HAS_POST]->(p2)
CREATE (u1)-[:HAS_POST]->(p3);

We could create the following schema, where type Post @node corresponds to a vertex with a :Post label, content: String to a content property on the vertex, and :HAS_POST edges are notated using the @relationship directive with type HAS_POST.

type Post @node {
    id: ID! @id
    content: String!
    creator: [User!]! @relationship(type: "HAS_POST", direction: IN)
}
 
type User @node {
    id: ID! @id
    name: String
    posts: [Post!]! @relationship(type: "HAS_POST", direction: OUT)
}

Create the application file

The application file will be used to setup the Neo4j GraphQL Library and connect to the running Memgraph instance.

Create the file:

touch index.js

Add the content below. Note that the schema we created above is used as a string literal for typeDefs:

import { Neo4jGraphQL } from "@neo4j/graphql";
import { ApolloServer } from '@apollo/server'
import { startStandaloneServer } from '@apollo/server/standalone';
import neo4j from 'neo4j-driver'
 
const typeDefs = `
type Post @node {
    id: ID! @id
    content: String!
    creator: [User!]! @relationship(type: "HAS_POST", direction: IN)
}
 
type User @node {
    id: ID! @id
    name: String
    posts: [Post!]! @relationship(type: "HAS_POST", direction: OUT)
}
`;
 
const driver = neo4j.driver(
    "bolt://localhost:7687",
    neo4j.auth.basic("", "")
);
 
const neoSchema = new Neo4jGraphQL({ typeDefs, driver });
 
const server = new ApolloServer({
    schema: await neoSchema.getSchema(),
});
 
const { url } = await startStandaloneServer(server, {
    context: async ({ req }) => ({
        req,
        sessionConfig: { database: "memgraph" },
        cypherQueryOptions: { addVersionPrefix: false }
    }),
    listen: { port: 4000 },
});
 
console.log(`🚀 Server ready at ${url}`);
 

To set up a GraphQL client against a running Memgraph instance, you have to specify the GraphQL schema, set up the used drivers, and specify Memgraph as the used database. Specifying the used database is especially important because the default database name in the driverConfig is not compatible with Memgraph. You must also use cypherQueryOptions: { addVersionPrefix: false } to ensure that any Cypher queries are compatible with Memgraph.

Run the application

Run the application using the following code:

node index.js

Interact with Memgraph

You are now ready to interact with Memgraph using GraphQL queries through the GraphQL server on localhost:4000 or 127.0.0.1:4000.

Running a GraphQL query on the example dataset, such as:

query Users {
  users {
    name
    posts {
      content
    }
  }
}

will yield the following results:

{
  "data": {
    "users": [
      {
        "name": "Alice",
        "posts": [
          {
            "content": "Alice's first post!"
          },
          {
            "content": "Another thought from Alice."
          }
        ]
      },
      {
        "name": "Bob",
        "posts": [
          {
            "content": "Bob's great idea."
          }
        ]
      }
    ]
  }
}