The Backend Interview Test - NETZSCH

• What we will see?

  • Clean code
  • Use of https://grpc.io/
  • Use of https://go-chi.io/#/
  • Use of https://gorm.io/docs/
  • Database Integration
  • Unit Tests

• Not a requirement, but will be good to see if possible:

  • Use of https://github.com/swaggo/swag and a public swagger documentation
  • The Docker file with the PostgresSQl, service, and APIs

Details

One of our customers bought a TVBox display, which can call APIs and display some books, a random book need to be displayed at the TVBox with the last book displayed (except at the first API request), and the TVBox will send this in an interval of 1m, the customer wants every next book not to be among the last 10 books displayed.

• The customer will send a request to our public service, and we need to provide some books about "Dungeon&Dragons" to be displayed on a TVBox at the company reception
  • He sent to us a list of the books he needs (see create_database.sql)
• The customer will need one public API with a hash authentication at the request header, just for authentication

Architecture

//                       All endpoint at public
//                       api need a header: "api-Key: string"
// 
//                           +-------------+               +---------------+       
// +-------------+           |             |               |               |       
// |             |           |             |               |               |       +---------------+
// |    User     |           |             |               |    Private    |       |               |
// |             |<----------|   Public    |<--------------|      API      |------>|    Database   |
// |             +---------->|             +-------------->|               |<------|               |
// |             |           |    Api      |      GRPC     |     GRPC      |       +---------------+
// |             |           |             |               |     only      |       
// |             |           |             |               |               |       
// +-------------+           |             |               |               |       
//                           +-------------+               +---------------+       

• Create a user hash to use at the body header
  • Key: Api-Key - Type: string

Public API

• Each endpoint will need to be validated with the Authentication Key given in the request header

GET - Create a simple endpoint to return the random book and the latest book displayed

• The first book displayed doesn’t need to have a latest_book
• The public-api will call the Private API GRPC service

GET - Create a simple endpoint to return the details from a book by the id

• The public-api will call the Private API GRPC service

Service API

You can generate the service with the private-service.proto file

GRPC - Create a simple endpoint to return the random book and the latest book displayed

• Get the next random book
  • Update the flag actual_book to true for the selected book
  • Update the flag actual_book to false for all other books
  • Make sure the book are not in the latest 10 books.
• If is the first call, the latest_book can be empty

GRPC - Create a simple endpoint to return the details from a book by the id

• Get one book by book_id from the database the book details and return it.

API Requests

• Request:

  curl -X GET 'https://localhost:9191/api/v1/books/random-one' -H "Auth-Key: HUAKAs123ASdk123lDIOQ"

• Return (example):

{
  "random_book": {...},
  "last_book": {...}
}        

The book details:

When the user select (touch) at the TVBox display to expand the book details, we will need more details about the book

• Request

    curl -X GET 'https://localhost:9191/api/v1/books/{book_id}'  -H "Auth-Key: HUAKAs123ASdk123lDIOQ"