kimmobrunfeldt / express-example

Example of good Express.js architecture with Promises and nice error handling

Express example

This example will not run! Some parts are not implemented.

This API specific Express app example is demonstrating in my opinion a good architecture.

You can also read these slides for presentation called "Good Express.js Architecture":

• PDF with speaker notes
• PDF without speaker notes

Note: the terminology in this exampls is a bit different than in the slides. controller = endpoint = http-layer and service = core = business logic.

Here's how the Express API application has been architectured in the example:

Good with this setup:

• Your code can leverage Promises

• Testable

  • Express app instance can be created with a function

  • Router instance can be created with a function

  • Core methods are testable. This would allow you to write some lower level tests.

    Note: even though they are testable, usually you get the best ROI by testing with real HTTP API calls. In other words: put your express app running locally, init db to certain state, and fire http requests to localhost with e.g. supertest lib.

• Provides a minimal but nice "frame" around your development with separation of concerns

• Error handling is done in one place, in the error-handling middlewares defined in app.js

• Your request handling code can throw errors and they will be handled at the app level

  No need to repeat the next(err) pattern in all your request handlers.