A Node API built by Cadell in 2020.
- Postgres and node-postgres for the database.
- TypeScript for type checking.
- Jest for testing.
- Express for routing.
Install dependencies first.
npm install
Start the Postgres database.
docker-compose up
Run the server with automatic restarts. Run in another terminal alongside the database.
npm run start
Run the tests with automatic restarts. Run in another terminal alongside the database.
npm run test:watch
Integration tests are the focus of this project, testing from the endpoint to the database and back again.
Postgres is run in a docker and is populated with some common test data that all tests can run against.
Then, for each test:
- We start a database transaction
- Supertest calls the endpoint.
- The response is validated.
- The database is validated.
- The transaction is rolled back leaving the database in a clean state.
Transactions mean that tests can run concurrently and you don't have to write any cleanup scripts.
Jest has a watch mode that runs the appropriate tests as you save your changes.
Each task has tags but how do we return the tags of each task without sacrificing performance?
The first way would be to check if your really need to display a toMany relationship in a list view. If it has more than a few results then you might be better off displaying the relations in a 'detail' view instead of a list.
Let's assume we definitely want to display tags on a list view. In that case I would recommend an upper limit of maybe 5 tags per task for example. You'll probably be limited by frontend real estate more than anything.
Fetch toMany relationships in a separate query based on the ids from an initial select which is filtered and paginated. This has the following advantages:
- The view and list logic has clear separation.
- The initial select can leave pagination to the database.
Other ORM solutions include:
- (Lazily) loading each toMany relation for each task, causing N+1 queries and poor performance (N is the number of tasks and 1 being the initial query).
- (Eagerly) joining the tags table. Pagination can no longer be done with limit and offset because they will refer to rows of tag-task combinations instead of just tasks. You can also only do this once or you'll run into other problems.
clean- remove coverage data, Jest cache and transpiled files,build- transpile TypeScript to ES6,build:watch- interactive watch mode to automatically transpile source files,test- run tests,test:watch- interactive watch mode to automatically re-run tests
The docker-compose.yml file that runs the Postgres database is from https://github.com/khezen/compose-postgres so you can follow the instructions from Access to PgAdmin.