Status Codes

Part of the Express Basics section of Coddy's Node.js journey. Lesson 7 of 20.

A program reads the status code before the body, so an error sent with 200 looks like a success.

app.get('/api/loans', (req, res) => {
    if (!req.query.member) {
        res.status(400).json({ error: 'Say which member' });
        return;
    }
    res.json(loansOf(req.query.member));
});

res.status(code) sets the status and returns res, so .json(...) can follow on the same line. return stops the function after the error. The codes you meet most:

200: it worked (the default).
201: something was created.
400: the request is wrong, like a missing field.
404: nothing is at that path or id.
500: the server failed.

Challenge

Easy

An unknown id on GET /api/recipes/:id answers 404 with { "error": "No such recipe" }.

Send GET /api/recipes/99 and GET /api/recipes/abc, then GET /api/recipes/3, and compare the statuses.

Try it yourself

import express from 'express';
import { recipes } from './data.js';

const app = express();

app.get('/', (req, res) => {
    res.send('Welcome to Recipe Box');
});

// type('text') sends plain text, so each title shows on its own line.
app.get('/recipes', (req, res) => {
    const { tag } = req.query;
    const list = tag ? recipes.filter((recipe) => recipe.tags.includes(tag)) : recipes;
    res.type('text').send(list.map((recipe) => recipe.title).join('\n'));
});

app.get('/recipes/:id', (req, res) => {
    const recipe = recipes.find((r) => r.id === Number(req.params.id));
    if (!recipe) {
        res.status(404).send('No such recipe');
        return;
    }
    res.send(recipe.title);
});

app.get('/api/recipes', (req, res) => {
    res.json(recipes);
});

app.get('/api/recipes/:id', (req, res) => {
    const recipe = recipes.find((r) => r.id === Number(req.params.id));
    if (!recipe) {
        res.status(404).send('No such recipe');
        return;
    }
    res.json(recipe);
});

app.get('/about', (req, res) => {
    res.send('Recipe Box collects family recipes.');
});

app.listen(3000, () => {
    console.log('Recipe Box is running on port 3000');
});