asp core crud example

asp-core-crud-example

A sample .NET Core project with a MongoDB database with replicaset and transactions enabled.

Goal

The goal of this project is to give a solution to the subject below (used for a job interview) :

Please create a sample .net/C# project that includes the following elements:
- Basic CRUD functionality for a data structure of your choice.
- RESTful APIs to expose that functionality with your framework of choice (ASP.NET Web APIs, ASP.NET Core, ServiceStack (preferred), …etc).
- Uses MongoDB using C# driver.
- Please demonstrate your usage of one of MongoDB advanced features (aggregation, transactions, indexes, …etc) using C# driver.
- Please push your code to a Git repository that you can share with us.

Project Architecture

This is a asp core 3.1 web API project with a n-tiers architecture :

• model layer
• business logic layer
• data access layer
• presentation layer (here, a REST API)

Each layer has its own abstraction layer in order to avoid dependencies. I'm using the stock .net core IOC and DI engine.

Tests

I didn't make any Unit Tests because there is no business logic. However, i've made a sample of an Integration Test using the Microsoft WebHost library. You can run the Integration Tests through visual studio or command line, but don't forget to run the docker-compose first (or else you won't have any database to request).

Database

The implementation of the DAL is using the MongoDB C# driver. By running the docker-compose attached to the solution, you will get an instance of a Mongo server with a replicaset enabled (in order to support transactions).

Transactions & (kind of) unit of work

As a demonstration of the usage of one of MongoDB advanced features, I've choosen transactions. So the IClientSessionHandle is injected in all repositories. I've also managed to make a middleware called TransactionFilter that creates a transaction for the whole HTTP request. This way, we can make multi-document operations, on different repositories, that may rollback if a problem happens, without dealing with multi-document transactions manually.

Example :

• Http request arrives
• Transaction opens
• Insert in XXX collection
• Update in YYY collection with the Id taken from XXX created previously
• The Update fails
• The transaction will abort and rollback the insertion of XXX

It's working as it is but it would need some more further load testing. This may not be production ready.

How to run ?

• Open the solution in Visual Studio
• Target the docker-compose project in the 00 - Solution Items folder
• Run with F5
• Wait for a few seconds (time for the replicaset to setup)
• Go to the swagger UI to make some requests : https://localhost:5000/swagger
• Watch the db in Mongo Express interface if needed : http://localhost:8081

Known bugs :

Using docker-compose up in commandline doesn't seem to work with the API at the moment. I didn't have much time left so I just kept using VS to compose.