/trades-api-flask

Primary LanguagePython

Python Flask: Stock Trades API

Project Specifications

Read-Only Files

  • tests/internal*

Environment

  • Python version: 3.7
  • Flask version: 1.1.2
  • Flask-SQLAlchemy: 2.4.4
  • Default Port: 8000

Commands

  • install:
python3 -m venv venv; source venv/bin/activate; pip3 install -r requirements.txt;
  • run:
flask init-db; flask run -p 8000
  • test:
pytest

Question description

In this challenge, your task is to implement a simple REST API to manage a collection of stock trades.

Each trade has the following structure:

  • id: The unique ID of the trade. (Integer)
  • type: The type of the trade, either 'buy' or 'sell'. (String)
  • user_id: The unique user ID. (Integer)
  • symbol: The stock symbol of the trade. (String)
  • shares: The total number of shares traded. The traded shares value is between 10 and 30 shares, inclusive. (Integer)
  • price: The price of one share of stock at the time of the trade. (Integer)
  • timestamp: The epoch time of the stock trade in milliseconds. (Integer)

What you have to do?

We would like to have a reusable, maintainable and testable code, so we want to create this API following some of those principles:

  • Clean code
  • SOLID principles
  • Decoupling
  • Design patterns
  • Error handling
  • Unit testing
  • TDD
  • Hexagonal architecture

You don't have to implement them all, but make the code better to be more comfortable with it.

Example of a trade data JSON object:

{
    "id": 1,
    "type": "buy",
    "user_id": 23,
    "symbol": "ABX",
    "shares": 30,
    "price": 134,
    "timestamp": 1531522701000
}

Requirements:

The REST service must expose the /trades endpoint, which allows for managing the collection of trade records in the following way:

POST /trades:

  • creates a new trade
  • expects a JSON trade object without an id property as a body payload. The shares value might be out of accepted [1, 100] range, and type might be invalid (i.e., not 'buy' or 'sell'), and in such cases, the API must return 400 error code. You can assume that besides that, the given payload is always valid.
  • if parameters are valid, adds the given trade object to the collection of trades and assigns a unique integer id to it. The first created trade must have id 1, the second one 2, and so on.
  • the response code is 201, and the response body is the created trade object

GET /trades:

  • returns a collection of all trades
  • the response code is 200, and the response body is an array of all trade objects ordered by their ids in increasing order
  • accepts the optional query parameter user_id. When user_id is provided, it returns trades of a specified user only.
  • accepts the optional query parameter type. When type is provided, it returns trades of a specified type only.

GET /trades/<id>:

  • returns a trade with the given id
  • if the matching trade exists, the response code is 200 and the response body is the matching trade object
  • if there is no trade with the given id in the collection, the response code is 404

DELETE, PUT, PATCH request to /trades/<id>:

  • the response code is 405 because the API does not allow deleting or modifying trades for any id value