File or folder	Description
`src/index.ts`	The entry file. This is where we setup middleware, attach routes, initialize database and express.
`src/routes.ts`	This is where we define all routes, both public and private.
`src/constants`	Constants are values that never change and are used in multiple places across the codebase.
`src/controllers`	Controllers listen to client's requests and work with entities and the database to fetch, add, update, or delete data.
`src/database`	Database related code and seeds go here.
`src/entities`	This is where we put TypeORM entities, you could think of them as models. We define columns, relations, validations for each database entity.
`src/errors`	This is where we define custom errors. The `catchErrors` function helps us avoid repetitive `try/catch` blocks within controllers.
`src/middleware`	Middleware functions can modify request and response objects, end the request-response cycle, etc. For example `authenticateUser` method verifies the authorization token and attaches `currentUser` to the request object.
`src/serializers`	Serializers transform the data fetched from the database before it's sent to the client.
`src/utils`	Utility(helper) functions that are used in multiple places across the codebase. For example `utils/typeorm.ts` functions help us validate data and avoid writing repetitive code.

What's missing?

There are features missing from this showcase API which should exist in a real product:

Migrations

We're currently using TypeORM's synchronize feature which auto creates the database schema on every application launch. It's fine to do this in a showcase product or during early development while the product is not used by anyone, but before going live with a real product, we should introduce migrations.

Proper authentication system

We currently auto create an auth token and seed a project with issues and users for anyone who visits the API without valid credentials. In a real product we'd want to implement a proper email and password authentication system.

Unit/Integration tests

This API is currently tested by the Client through end-to-end Cypress tests. That's good enough for a relatively simple application such as this, even if it was a real product. However, as the API grows in complexity, it might be wise to start writing additional API-specific unit/integration tests.