Ruby on Rails: Stock Trades API

Project Specifications

Read-Only Files

• spec/*
• db/migrate/*

Environment

• Ruby version: 2.7.1
• Rails version: 6.0.2
• Default Port: 8000

Commands

• run:

bin/bundle exec rails server --binding 0.0.0.0 --port 8000

• install:

bin/env_setup && source ~/.rvm/scripts/rvm && rvm --default use 2.7.1 && bin/bundle install

• test:

RAILS_ENV=test bin/rails db:migrate && RAILS_ENV=test bin/bundle exec rspec

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

Example of a trade data JSON object:

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

Requirements:

The model implementation is provided, you may add methods, but you cannot alter its schema. It has a timestamp field of DateTime type, which must be serialized to/from JSON's timestamp of integer type.

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

POST request to /trades

• creates a new trade
• expects a JSON trade object without an id property as a body payload. You can assume that the given object is always 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 request to /trades

• return a collection of all trades
• the response code is 200, and the response body is an array of all trades objects ordered by their ids in increasing order
• optionally accepts query parameters trade_type and user_id, for example /trades?trade_type=buy&user_id=122. All these parameters are optional. In case they are present, only objects matching the parameters must be returned.

GET request to /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