README.md

Backend developer application guide

Build a GraphQL API: CRUD and Caching

Welcome to the guide for applying as a backend developer! In this document, you'll find instructions on how to build a GraphQL API with essential features like CRUD operations and caching.

Get started

Run

npm i
docker compose up

Prerequisites

• Use knex to query builder
• Use Redis for caching (add to docker-compose)
• Use Apollo sandbox to run queries (leave queries organized so we can run them live)

Functional Prerequisites

1. We expect all resolvers to be implemented (use pre-defined types on schema.graphql to guide)

   • Define resolvers to query for user (sorted playlists by name)
   • Define resolvers to query for songs (sorted by name)
   • Define resolvers to query for playlists (sorted by name)
   • Define mutation to add/remove song
   • Define mutation to add/remove playlist
   • Define mutation to add/remove song from playlist
   • Define mutation to update user

2. Implement a Cache-Aside strategy

   • Lazy Loading: The query User should be fully cached through Lazy Loading (Implement availability with cache hit and cache miss)

     • Ensure the cache invalidation when changes occur in user email only
     • E.g., query User

     query Query($userId: ID!) {
       user(id: $userId) {
         id
         email
         name
         playlists {
           id
           name
           songs {
             id
             name
           }
         }
         songs {
           id
           name
         }
       }
     }
     

   • Write Through - reverse the order of how the cache is populated (only after lazy loading)

     • Should change the cache first and then the Postgres, apply on the following mutations:
       • add / remove songs for a user
       • add / remove songs for a playlist
       • add / remove playlists for a user
     • Keep cache lists sorted

3. PLUS: Write integration tests for resolvers, mutations and cache

How to Share Your Work

When you're ready to share your completed application, follow these steps:

1. Fork and Commit: Fork this repository and commit your developed code to the new forked repository.
2. GitHub Repository: Push your forked repository to your GitHub account.
3. Share the Link: Once your code is on GitHub, share the repository link with us. This will enable us to review your application effectively.