andlehma / andrew-lehman-ei-assessment-api

Andrew Lehman's assessment for Expert Institute

Expert Institute Assessment API

This project is part of the intervew process at Expert Institute.

I was given the choice to create either a frontend or an API, and I chose to create an API, becuase I am under a time constraint and I have been working on the backend for the past two years.

Running Locally

npm install
npm run serve

API will be live on localhost:3000 or whatever port is specified in the environment variable PORT.

Testing

npm run test

API Endpoints

GET /assets

Lists all asset types

Params

• limit specifies how many assets to return
• offset specifies which asset to start the page on
  • For example, ?limit=10&offset=35 will return assets 36-45.
• search allows filtering on the id of the asset
• sort specifies which key to sort on
  • defaults to descending, put - in front of the parameter for ascending. ex: ?sort=-priceUsd

GET /assets/{{id}}

Returns details for the specified asset

GET /convert/{{id}}

Converts the specified asset to usd. Provide an amount in the query parameters

• ex: /convert/bitcoin?amount=3.5

GET /users

Lists all users in the database. Definitely wouldn't want to have this in a production app, but it's useful for this demo.

POST /users

Create a new user. A more robust user creation solution is out of scope for this project.

Expects a body with a user id and a user name:

{
    "id": 3,
    "userName": "Andrew Lehman"
}

GET /user/{{id}}

Returns details about the specified user.

GET /userAssets

Lists all assets owned by users. Again, this wouldn't be exposed in a real app.

GET /myAssets

Lists assets owned by the specified user.

Requres an authorization token.

For the purposes of this demo, the authorization token is equivalent to the User ID. In a real application, this would be a secure token which is refreshed periodically and on every login.

Token should be in the form Bearer {{id}} and should be passed as an authorization header.

POST /addAssets

Requires an authorization token.

Requires a body with an asset ID and an amount

{
    "assetId": "ethereum",
    "amount": 7.89
}

To remove assets, provide a negative amount.

GET /gainOverTime/{{id}}

Returns net gain/loss over a period of holding a specified asset.

Expects an acquired parameter, e.g. /gainOverTime/bitcoin?acquired=2018-06-29. In a real app, we would store the date that the user acquired the asset. That functionality is out of scope for this demo, so this endpoint requires you to specity a date. Format is anything Javascript can parse into a Date object.

Limitations

Because of the time constraint, the scope of this project is quite limited.

Security

I have decided that security is entirely out of scope. For user-specific tasks, an authorization token is requird, but it's just the User ID, which is not secure at all. In a real app like this, especially one dealing with money, security is, of course, hugely important. However, I am under limited time, and security is really hard.

Database

I'm using a SQLite database for this project. The database is destroyed and re-created every time the app is run. This makes local testing and development much simpler. Also, I am not a DB admin, so my schema and my SQL scripts could probably be better.

Transactions

A real app like this would have a database table of transactions, but I have decided that such a table is out of scope for this project.

Integration Test Data

Currently, the data in the integration tests just lives in a SQL file. I would prefer to populate the test db with generated data using a framework like faker.js