📑 Apollo Server

Apollo Server

for (const [name, value] of Object.entries(option.headers)) {
	res.setHeader(name, value)
}

function getMiddleware({ path, cors, bodyParser } = {}) {
	const router = express.Router()
	router.use(path, (_req, _res, next) => {
		Promise.resolve()
			.then(next)
			.catch(next)
	})
}

📑 async, await

• async/await works with most loops, but won’t work with loops that require a callback.
• For example, for(), for-of works, but forEach, map, filter, and reduce NOT.
• forEach is not promise-aware. It cannot support async and await. You cannot use await in forEach.

• map:

  const promises = ary.map(async item => Promise.resolve(item))
  
  await Promise.all(promises)

📑 Key Takeaways

1. If you want to execute await calls in series, use a for-loop (or any loop without a callback).
2. Don’t ever use await with forEach. Use a for-loop (or any loop without a callback) instead.
3. Don’t await inside filter and reduce. Always await an array of promises with map, then filter or reduce accordingly.

📑 Sequelize

bin/init_db.sh:

$ npm install -g sequelize-cli

• create
• update, save
• findAll
• findByPk
• findOne
• findOrCreate
• findAndCountAll
• count
• max
• min
• sum

📑 Reference

1. apllographql fullstack-tutorial final branch
2. graphql-bookstore

📑 Steps

• utils.js
• databases/
• resolver.js
• schema.js
• server.js
• Setup DB, here is sqlite3: Not use sequelize init to create configs/ and models/ folders, just a simple utils.js
• create models: define Sqlite3-Schema in utils.js
• inside databases/ folder, extends apollo-datasource class to implement crud
• define apollo-server schema.js, mapping utils.js sqlite3 schema.
• define resolver.js, associate databases-middleware with schema/utils.
• inject to apollo-server: {typeDefs, resolvers, datasources}
• test

🪕 QA:

• There are at least two GraphQL clients available:

  • Relay, the former implementation by Facebook, highly tangled together with React;
  • Apollo, which strives to be a framework-agnostic (不可知论的) project.