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LESSON 30 OF 188 · BACKEND: YOUR FIRST API

Only the First Few in Python

Practice

A real shop can have thousands of products, and a page often shows only a few. A client asks for that with a query parameter: ?limit=2 means "at most 2 products".

To keep the first few items of a list, use a slice. items[:n] goes from the start up to, but not including, position n. If n is bigger than the list, you simply get the whole list.

days = ["Mon", "Tue", "Wed", "Thu", "Fri"]
print(days[:2])    # ['Mon', 'Tue']
print(days[:10])   # the whole list, no error

Cut the list last, after filtering and sorting, so ?sort=price&limit=2 gives the two cheapest products. A limit of 0 or less makes no sense, so it gets 400. Without limit, the answer is the whole list, as before. The lists below show product names only.

GET /products?limit=2  →  200  [Mug, Notebook]
GET /products?sort=price&limit=2  →  200  [Pen, Notebook]
GET /products?category=office&limit=1  →  200  [Notebook]
GET /products?limit=10  →  200  [Mug, Notebook, Lamp, Pen]
GET /products?limit=0  →  400  {"error": "Limit must be 1 or more"}
GET /products?limit=-3  →  400  {"error": "Limit must be 1 or more"}

Your task: in GET /products, read limit as a whole number, answer 400 when it is less than 1, and cut the list to its first limit products.


Assignment
Follow the Coding Tutorial to add a limit to GET /products.


Hint
Read limit with type=int, like max_price. Check it before the loop, and slice result just before the return, after the sorting.


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    Shop Limit in Python

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