index.js

const express = require("express");
const { postgraphile } = require("postgraphile");
const PostGraphileNestedMutations = require("postgraphile-plugin-nested-mutations");
const SimplifyInflectorPlugin = require("@graphile-contrib/pg-simplify-inflector");

const app = express();

app.use(
  postgraphile(process.env.DATABASE_URL, "public", {
    watchPg: true,
    graphiql: true,
    enhanceGraphiql: true,
    appendPlugins: [PostGraphileNestedMutations, SimplifyInflectorPlugin],
  })
);

app.listen(3000);

package.json

{
  "name": "pgpnm_29",
  "version": "1.0.0",
  "main": "index.js",
  "license": "MIT",
  "dependencies": {
    "@graphile-contrib/pg-simplify-inflector": "^6.1.0",
    "express": "^4.17.1",
    "postgraphile": "^4.11.0",
    "postgraphile-plugin-nested-mutations": "^1.1.0"
  },
  "scripts": {
    "start": "node index.js"
  }
}