オブジェクト型

type Query {
  rollDice(numDice: Int!, numSides: Int): [Int]
}

type RandomDie {
  roll(numRolls: Int!): [Int]
}

type Query {
  getDie(numSides: Int): RandomDie
}

class RandomDie {
  constructor(numSides) {
    this.numSides = numSides
  }

  rollOnce() {
    return 1 + Math.floor(Math.random() * this.numSides)
  }

  roll({ numRolls }) {
    var output = []
    for (var i = 0; i < numRolls; i++) {
      output.push(this.rollOnce())
    }
    return output
  }
}

var root = {
  getDie: ({ numSides }) => {
    return new RandomDie(numSides || 6)
  },
}

type RandomDie {
  numSides: Int!
  rollOnce: Int!
  roll(numRolls: Int!): [Int]
}

type Query {
  getDie(numSides: Int): RandomDie
}

var express = require("express")
var { createHandler } = require("graphql-http/lib/use/express")
var { buildSchema } = require("graphql")

// Construct a schema, using GraphQL schema language
var schema = buildSchema(`
  type RandomDie {
    numSides: Int!
    rollOnce: Int!
    roll(numRolls: Int!): [Int]
  }

  type Query {
    getDie(numSides: Int): RandomDie
  }
`)

// This class implements the RandomDie GraphQL type
class RandomDie {
  constructor(numSides) {
    this.numSides = numSides
  }

  rollOnce() {
    return 1 + Math.floor(Math.random() * this.numSides)
  }

  roll({ numRolls }) {
    var output = []
    for (var i = 0; i < numRolls; i++) {
      output.push(this.rollOnce())
    }
    return output
  }
}

// The root provides the top-level API endpoints
var root = {
  getDie: ({ numSides }) => {
    return new RandomDie(numSides || 6)
  },
}

var app = express()
app.all(
  "/graphql",
  createHandler({
    schema: schema,
    rootValue: root,
  })
)
app.listen(4000)
console.log("Running a GraphQL API server at localhost:4000/graphql")

{
  getDie(numSides: 6) {
    rollOnce
    roll(numRolls: 3)
  }
}