Exercise #07 - ShoppingCart

Write a server that manages a shopping cart.
This is the first exercise that involves JSON. Items in the cart will look like { "model": "something", "quantity": 10 }.

A cart is just a list of items. Items are appended at the end of the cart.
Only adding items is supported. Expose two routes:

The cart starts empty. Don't worry about the same item getting added twice for now. 

    GET /cart
    >>> expected []

    POST /cart
    { "model": "first thing", "quantity": 2 }

    GET /cart
    >>> expected
      [
        { "model": "first thing", "quantity": 2 }
      ]

    POST /cart
    { "model": "another thing", "quantity": 30 }

    GET /cart
    >>> expected
      [
        { "model": "first thing", "quantity": 2 },
        { "model": "another thing", "quantity": 30 }
      ]

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Reference node.js implementation

          
const app = require("express")()
const bodyParser = require("body-parser")

app.use(bodyParser.json())

// Mutable state!
let currentCart = []

app.post("/cart", (req, res) => {
  const item = req.body

  if (item.model && item.quantity)
  {
    currentCart.push(item)
    res.send("ok")
  }
  else {
    throw new Error("Not a valid item")
  }
})

app.get("/cart", (req, res) => {
  res.json(currentCart)
})

console.log("Starting server...")
app.listen(7879)

Where to get help

Got stuck? Don't worry! Join the discussion on Github (issue #7). It might be that the exercise could be clearer or there's something you really can't wrap your head around. That's totally fine! 🙂

You can also have a look at my solution. No shame in having a peek. 🧐
But do share your thoughts on the exercises, it would be really helpful!