Generating typescript definitions from .graphql files using apollo-codegen and graphql-code-generator

regen-domain-types.js

const { introspectSchema } = require("apollo-codegen");
const { executeWithOptions } = require("graphql-code-generator/dist/cli");
const fs = require("fs");
const path = require("path");

const graphqlPath = "./src/graphql/";
const schemaInput = "./src/graphql/temp.graphql";
const jsonOutput = "./src/graphql/temp.json";
const dtsOutput = "./src/graphql/domain.d.ts";

function regen() {
  cleanTempFiles();
  combineSchema(schemaInput);
  introspectSchema(schemaInput, jsonOutput)
    .then(async () => {
      const dts = await executeWithOptions({
        file: jsonOutput,
        out: dtsOutput,
        template: "typescript",
        schema: true
      });
      fs.writeFileSync(dts[0].filename, dts[0].content);
    })
    .catch(err => {
      console.log(err);
    })
    .then(() => {
      cleanTempFiles();
    });
}

function cleanTempFiles() {
  if (fs.existsSync(schemaInput)) {
    fs.unlinkSync(schemaInput);
  }
  if (fs.existsSync(jsonOutput)) {
    fs.unlinkSync(jsonOutput);
  }
}

function combineSchema(outputFilename) {
  const files = fs.readdirSync(graphqlPath);
  const schemas = files.filter(f => f.endsWith(".graphql"));
  const outputFile = fs.openSync(outputFilename, "ax");
  schemas.forEach(s =>
    fs.appendFileSync(outputFile, fs.readFileSync(path.resolve(graphqlPath, s)))
  );
  fs.closeSync(outputFile);
}

regen();