apollo-context-example.js

const express = require ('express')
const { ApolloServer, gql } = require('apollo-server-express')

const typeDefs = gql`

    type Query {
        greeting: String
    }
`
const resolvers = {
    Query: {
        greeting: (root, args, context) => {
            return `hello ${context.username}`
        }
    }
}

const createContext = (request) => {

    if(!request.req.headers.authorization)
        return { username: 'Unknown' }
    else
        return { username: getUserFromToken(request.req.headers.authorization) }

}

const server = new ApolloServer({typeDefs, resolvers, context: createContext})

const app = express()

server.applyMiddleware( {app} )

app.listen({port: 4000}, () => {
    console.log('Server is running')
})