User API Challenge: C#

We have a fictitious scenario where we'd like to build an API to manage app users. We require the ability to create, get, and list users. Once we create users, we need the ability for the user to create an account.

This should be implemented with an API and database.

Read the full scenario and technical requirements in Requirements.md

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User API Solution

Overview

This application follows standard ASP.Net WebAPI structure with CQRS design pattern.

Project uses MediatR package for separation of Domain and Application logic.
All the application logic and business rules are implemented in the respective Handlers. The Controllers are only responsible for accepting a request and delegating them to MediatR to route them to the correct handler.

Application Domain contains 2 main entities User and Account. This project uses PostgreSQL for data persistance.

Folder Structure

TestProject.WebAPI
    /Domain -  Domain Entity classes
    /Commands - Command/Request/Reponse type definitions per entity 
    /Queries - Query/Request/Reponse type definitions per entity
    /Handlers - This is the application layer which implement the required business logic and db operations  
    /Controllers
        /UsersController - Apis for Users 
        /AcccountsController - Apis for Accounts
    /Models - Contains Database context 

Building

Build using IDE or CLI

Only application build then use
    dotnet build

Docker Build as below 
    cd /source/repos/users-api/TestProject.WebAPI
    docker-compose up --build 

DB Migrations are added into Application startup

Testing

This api can be tested in following ways

1. By Running Unit Tests

       Via CLI 
   
           cd /source/repos/users-api/TestProject.Tests
           dotnet test
   
       Or Use a test runner in the IDE 
   

2. By Running Api as Docker container and use PostMan or Curl for sending requests

       In CLI , which will build and run the application and db containers
   
       cd /source/repos/users-api/TestProject.WebAPI
       docker-compose up --build 
   
   

Once the app and db containers are running we can make following API requests

Health check

Request

    GET http://localhost:8000/api/users

Response

        200 OK
        Api is running.

Create User

Request

    curl --location --request POST 'http://localhost:8000/api/users/create' \
    --header 'Content-Type: application/json' \
    --data-raw '{"name": "test" , "email": "test@email.com", "salary": 10000 , "expenses": 1500}'

Response

    201 Created

    {
        "type": "CreateUserResponse",
        "id": "48d9159d-2b2d-4531-b99b-670afc1971c7",
        "status": "Success"
    }

Create Account

Request

    curl --location --request POST 'http://localhost:8000/api/accounts/create' \
    --header 'Content-Type: application/json' \
    --data-raw '{
        "userid": "48d9159d-2b2d-4531-b99b-670afc1971c7"
    }'

Response

    201 Created

    {
        "type": "CreateAccountResponse",
        "id": "ec899376-3718-4b3b-aa75-8012b9fdcb5d",
        "status": "Success"
    }

List Users

Request

    curl --location --request GET 'http://localhost:8000/api/users/list'

Response

    200 Ok

    [
        {
            "type": "ListUsersResponse",
            "id": "47f144d4-1c89-4e42-95a7-9014b82f2570",
            "name": "test",
            "email": "test1@email.com"
        },
        {
            "type": "ListUsersResponse",
            "id": "7eebd0f6-a2af-4a82-958b-a28bd52b05c8",
            "name": "test",
            "email": "test10@email.com"
        }
    ]

Get User

Request

    curl --location --request GET 'http://localhost:8000/api/users/7eebd0f6-a2af-4a82-958b-a28bd52b05c8'

Response

    200 Ok

    {
        "type": "GetUserResponse",
        "id": "7eebd0f6-a2af-4a82-958b-a28bd52b05c8",
        "name": "test",
        "email": "test10@email.com",
        "salary": 10000,
        "expenses": 1500,
        "accounts": [
            {
                "id": "1a2b9b1d-b5b5-4753-a1d6-6f7c8c0609c5",
                "name": "Wallet 9981509",
                "status": 0,
                "balance": 0,
                "userId": "7eebd0f6-a2af-4a82-958b-a28bd52b05c8"
            },
            {
                "id": "ec899376-3718-4b3b-aa75-8012b9fdcb5d",
                "name": "Wallet 0035283",
                "status": 0,
                "balance": 0,
                "userId": "7eebd0f6-a2af-4a82-958b-a28bd52b05c8"
            }
        ]
    }

List Accounts

Request

    curl --location --request GET 'http://localhost:8000/api/accounts/list'

    200 OK

    [
        {
            "type": "ListAccountsResponse",
            "id": "9b4f9d12-731e-4361-a5aa-b976e4c7ac8e",
            "userId": "7a8419ba-ab3c-4a3c-8241-84acafecb667",
            "name": "Wallet 2808765",
            "status": 0,
            "balance": 0
        },
        {
            "type": "ListAccountsResponse",
            "id": "32739e8e-6f1f-4eec-8460-37db99df810a",
            "userId": "7a8419ba-ab3c-4a3c-8241-84acafecb667",
            "name": "Wallet 9563500",
            "status": 0,
            "balance": 0
        },
    ]

Deploying

This project has Docker support, containers can be deployed using docker-compose shown in above sections.

Additional Information

Further Improvements

• Use a standard API media type such as JsonApi for standardised serialization instead of custom JSON for every API
• Application Logging for better diagnosis
• Use AutoMapper for concise code for mapping between domain and request/response objects
• Create a repository for handling DB oprations so that it can be separted from handlers.
• Add Swagger support for better API documnetation
• Move DB Migrations out of application start up for better performance