Guided Practice - Notepad

This repo contains a barebones API that tracks a list of notes. In this guided practice, you'll set up error handling middleware and refactor the existing routes into a separate router.

Getting Started

1. Create a new repository using this one as a template.
2. Clone down your repository and run npm install to install the dependencies.
3. Start the development server with npm run dev.
4. Test the requests in .http. They should all be working, except for the POST request!

Adding Middleware

1. Right before app.listen, add a catch-all middleware that calls next with a status of 404 and the message "Endpoint not found". This will be the default 404 middleware.

   See solution

   app.use((req, res, next) => {
     next({ status: 404, message: "Endpoint not found." });
   });

2. Right after your new 404 middleware but before app.listen, add a default error-handling middleware. Log the error to the console with console.error. The response status should default to 500, unless the error has a status. Similarly, the response message should default to "Sorry, something went wrong!", unless the error has a message.

   See solution

   app.use((err, req, res, next) => {
     console.error(err);
     res.status(err.status ?? 500);
     res.json(err.message ?? "Sorry, something went wrong!");
   });

3. The handlers for GET /notes/:id and POST /notes directly send an error response when the request fails. Refactor them to call next instead with the corresponding status and message.

   See solution

   - res.status(404).send(`Note with id ${id} does not exist.`);
   + next({ status: 404, message: `Note with id ${id} does not exist.` });

   - res.status(400).send(`New note must have text.`);
   + next({ status: 400, message: `New note must have text.` });

4. Add middleware near the top of the file to parse JSON. The POST request in .http should now work.

   See solution

   app.use(express.json());

At this point, every request in .http should work. Add more requests to make sure errors are handled correctly!

Refactoring to Router

1. In api/notes.js, create a new Express Router and export it.

   See solution

   const express = require("express");
   const router = express.Router();
   module.exports = router;

2. Remove the notes import from server.js. Import the notes array into api/notes.js instead.

   See solution

   const notes = require("../data/notes");

3. Move the 3 /notes middleware from server.js into api/notes.js. Use the router variable instead of app, and remove /notes from the path of each middleware.

   See solution

   router.get("/", (req, res) => {
     // unchanged
   });
   
   router.get("/:id", (req, res, next) => {
     // unchanged
   });
   
   router.post("/", (req, res, next) => {
     // unchanged
   });

4. In server.js, where the /notes middleware used to be, add middleware to route /notes to the router exported from api/notes.js.

   See solution

   app.use("/notes", require("./api/notes"));

5. Test the requests in .http to ensure that they all still work.

Solution

The final solution code can be viewed in the solution branch of the starter repository.