Microservices Using ASP.NET, PostgreSQL, Dapper Micro-ORM and Docker Container
By: Mehmet Özkaya
Tags: Pgadmin, Microservices, Aspnetcore, Postgresql, Dapper

Building Discount Microservice on .Net platforms which used Asp.Net Web API, Docker, PostgreSQL, Dapper Micro-ORM and Swagger. Test microservice with using Postman.

Introduction

In this article we will show how to perform Discount Microservices operations on ASP.NET Core Web application using PostgreSQL, Dapper micro-orm, Docker Container and Swagger.

By the end of the article, we will have a Web API which implemented CRUD operations over Coupon objects. These objects will be store in PostgreSQL database and retrieved data with using Dapper micro-orm tool.

Developing Discount microservice which includes;

ASP.NET Web API application

application REST API principles, CRUD operations

principles, operations PostgreSQL database connection and containerization

connection and containerization Repository Pattern implementation

implementation Using Dapper for micro-orm implementation to simplify data access and ensure high performance

implementation to simplify data access and ensure high performance PostgreSQL database connection and containerization

We will Analysis and Architecting of Discount Microservices, applying N-Layer architecture. Containerize Discount Microservices with PostgreSQL database using Docker Compose.

In the upcoming sections :

ASP.NET Grpc Server application

Build a Highly Performant inter-service gRPC Communication with Discount Microservice

with Discount Microservice Exposing Grpc Services with creating Protobuf messages

So in this section, we are going to Develop Discount.API Microservices with PostgreSQL.

Background

You can follow the previous article which explains overall microservice architecture of this example.

Check for the previous article which explained overall microservice architecture of this repository.

We will focus on Discount microservice from that overall e-commerce microservice architecture.

Step by Step Development w/ Udemy Course

Get Udemy Course with discounted — Microservices Architecture and Implementation on .NET.

Source Code

Get the Source Code from AspnetRun Microservices Github — Clone or fork this repository, if you like don’t forget the star. If you find or ask anything you can directly open issue on repository.

Prerequisites

Install the .NET Core 5 or above SDK

Install Visual Studio 2019 v16.x or above

Docker Desktop

PostgreSQL in Discount Microservices

PostgreSQL is an open source and completely free object relational database system with powerful features and advantages. Taking advantage of the security, storability and scalability features of the SQL language, PostgreSQL is also used as a database manager in many areas.

PostgreSQL is one of the most accepted database management systems in the industry today. Because it offers users the advantages of successful data architecture, data accuracy, powerful feature set, and open source. PostgreSQL is supported by many major operating systems such as UNIX, Linux, MacOS and Windows.

In terms of performance, PostgreSQL has been found to be more successful compared to other commercial or open source databases.

In the face of some database systems, it is fast in some areas, but slow in others.

Compared to PostgreSQL, MySQL and databases in the same class, it is slower in INSERT / UPDATE transactions because it works transaction-based.

In some cases, PostgreSQL and MySQL have significant advantages in terms of features, reliability and flexibility. Aside from the highlights of PostgreSQL, this service is offered completely free of charge by open source developers.

For Discount microservices, we are going to store discount coupon data information into PostgreSQL database in a Coupon table.

Analysis & Design

This project will be the REST APIs which basically perform CRUD operations on Basket databases.

We should define our Discount use case analysis. In this part we will create Coupon entities. Our main use case are Get Coupon by ProductName, able to add new item to Discount. Also performed CRUD operations on Coupom entity.

Our main use cases;

Get Coupon with productname

Update Coupon

Delete Coupon

Checkout Coupon

Architecture of Discount microservices

We are going to use traditional N-Layer architecture. Layered architecture basically consists of 3 layers. These 3 layers are generally the ones that should be in every project. You can create a layered structure with more than these 3 layers, which is called multi-layered architecture.

Data Access Layer: Only database operations are performed on this layer.

The task of this layer is to add, delete, update and extract data from the database. There is no other operation in this layer other than these operations.

Business Layer: We implement business logics on this layer. This layer is will process the data taken by Data Access into the project.

We do not use the Data Access layer directly in our applications.

The data coming from the user first goes to the Business layer, from there it is processed and transferred to the Data Access layer.

Presentation Layer: This layer is the layer on which the user interacts.

It could be in Windows form, on the Web, or in a Console application.

The main purpose here is to show the data to the user and to transmit the data from the user to the Business Layer and Data Access.

Simple Data Driven CRUD Microservice

Discount.API microservices will be simple crud implementation on Coupom data on PostgreSQL databases.

You can apply any internal design pattern per microservices. Since we have 1 project, so we are going to separate this layers with using folders into the project.

But for the ordering microservices we also separate layers with projects with using clean arch and CQRS implementation.

So we don’t need to separate layers in different assemblies.

If we look at the project structure, we are planning to create this layers,

Domain Layer — Contains business rules and logic.

Application Layer — Expose endpoints and validations. API layer will be Controller classes.

Infrastructure Layer — responsible by persistence operations.

Project Folder Structure

Entities — PostgreSQL entity

Data — PostgreSQL data context

Repositories — PostgreSQL repos

Controllers — api classes

Setup PostgreSQL Docker Database for Discount.API Microservices

We are going to Setup PostgreSQL Docker Database for Discount.API Microservices.

First, We should go to DockerHub and find Postgres official image.

Postgres DockerHub;

https://hub.docker.com/_/postgres

This time we are going to write directly on docker-compose file.

docker-compose.yml

version: ‘3.4’ services:

catalogdb:

image: mongo basketdb:

image: redis:alpine discountdb: — — ADDED

image: postgres

… volumes:

portainer_data:

postgres_data: — — ADDED

—

Check environment variables - https://hub.docker.com/_/postgres

pgdata username etc..

—

docker-compose.override.yml

discountdb:

container_name: discountdb

environment:

— POSTGRES_USER=admin

— POSTGRES_PASSWORD=admin1234

— POSTGRES_DB=DiscountDb

restart: always

ports:

— “5432:5432”

volumes:

— postgres_data:/var/lib/postgresql/data/

We have added postgresql database in our dc file. We have not started yet, because we also need to manage portal of postresql.

Setup pgAdmin Management Portal for PostgreSQL Database for Discount.API Microservices

We are going to Setup pgAdmin Manage Portal for PostgreSQL Database for Discount.API Microservices.

pgAdmin is one of the popular and feature rich Open Source administration and development platform for PostgreSQL.

We will use pgAdmin for managing PostgreSQL Discount database creation and add same records into that table for Discount microservices.

We should go to DockerHub and find pgAdmin image.

— now its time to add manage portal of postresql whic is pgadmin.

Check env variables

https://www.pgadmin.org/docs/pgadmin4/latest/container_deployment.html

Run a simple container over port 80, setting some configuration options:



docker run -p 80:80 \

-e ‘

-e ‘PGADMIN_DEFAULT_PASSWORD=SuperSecret’ \

-e ‘PGADMIN_CONFIG_ENHANCED_COOKIE_PROTECTION=True’ \

-e ‘PGADMIN_CONFIG_LOGIN_BANNER=”Authorised users only!”’ \

-e ‘PGADMIN_CONFIG_CONSOLE_LOG_LEVEL=10’ \

-d dpage/pgadmin4 docker pull dpage/pgadmin4docker run -p 80:80 \-e ‘ PGADMIN_DEFAULT_EMAIL=user@domain.com ’ \-e ‘PGADMIN_DEFAULT_PASSWORD=SuperSecret’ \-e ‘PGADMIN_CONFIG_ENHANCED_COOKIE_PROTECTION=True’ \-e ‘PGADMIN_CONFIG_LOGIN_BANNER=”Authorised users only!”’ \-e ‘PGADMIN_CONFIG_CONSOLE_LOG_LEVEL=10’ \-d dpage/pgadmin4

After getting these informations, its time to add this into our docker-compose file with postgreSQL

write dc

docker-compose.yml

version: ‘3.4’

… discountdb:

image: postgres pgadmin: — — — — — — — — — — ADDED

image: dpage/pgadmin4 volumes:

portainer_data:

postgres_data:

pgadmin_data: — — — — — — — ADDED

docker-compose.override.yml



container_name: pgadmin

environment:

— PGADMIN_DEFAULT_EMAIL=admin@aspnetrun.com

— PGADMIN_DEFAULT_PASSWORD=admin1234

restart: always

ports:

— “5050:80”

volumes:

— pgadmin_data:/root/.pgadmin pgadmin:container_name: pgadminenvironment:— PGADMIN_DEFAULT_PASSWORD=admin1234restart: alwaysports:— “5050:80”volumes:— pgadmin_data:/root/.pgadmin

So now we had postgres database and also pgadmin management tool of postgres.

RUN with below command on that location;

docker-compose -f docker-compose.yml -f docker-compose.override.yml up -d

docker-compose -f docker-compose.yml -f docker-compose.override.yml down

Check portainer containers

localhost:9000

Check pgAdmin

localhost:5050

Login system with

— PGADMIN_DEFAULT_EMAIL=admin@aspnetrun.com

— PGADMIN_DEFAULT_PASSWORD=admin1234

After taht we can manage our postgresql database with adding new server and connect to our discountdb database.

Add New Server

General

name — DiscountServer Connection

hostname — discountdb — this should be the docker container name of postresql

username — admin

password — admin1234



See dc-override of postresql

discountdb:

container_name: discountdb

environment:

— POSTGRES_USER=admin

— POSTGRES_PASSWORD=admin1234

See “DiscountDb” database under servers.

You can create tables under schemas.

As you can see that, we have added pgAdmin management portal of postgresql database in our dc file. And run our docker-compose file and see that we can manage our postgresql database in pgAdmin portal like adding new server and see our Discount db.

Create Coupon Table in the DiscountDb of PostgreSQL Database with pgAdmin Management Portal

We are going to Create Coupon Table in the DiscountDb of PostgreSQL Database with pgAdmin Management.

See “DiscountDb” database under servers.

You can create tables under schemas.

Open in pgadmin

Tools — Query Tool

Create Table with below script

Tools — Query Tool CREATE TABLE Coupon(

ID SERIAL PRIMARY KEY NOT NULL,

ProductName VARCHAR(24) NOT NULL,

Description TEXT,

Amount INT

);

Now our Postresql database and table is ready and loaded with predefined data.

Developing Discount.API Microservices Creating Entities

We should create entity objects for redis definitions.

Create “Entities” folder

Entities

Add Coupon class

namespace Discount.API.Entities

{

public class Coupon

{

public int Id { get; set; }

public string ProductName { get; set; }

public string Description { get; set; }

public int Amount { get; set; }

}

}

Developing Repository Pattern Connect PostgreSQL use Dapper on Discount.API Microservice

We are going to Developing Repository Pattern Connect PostgreSQL use Dapper on Discount.API Microservice.

We will encapsulate data related objects in the repository classes by this way there is an abstraction with the repository layer.

First of all, we should install required nuget packages

Install Nuget Package

Open Package Manager Console — PMC

Select Project — Discount.API

Run Command:

Install-Package Npgsql

Install-Package Dapper

If required Update Packages

Update-Package -ProjectName Discount.API

Dapper

Dapper is a Micro-ORM (Object Relationship Mapper) tool developed by the Stack Overflow team as LightWeight, published open source on Github. It has support for most databases (SQL Server, MySQL, PosgreSQL so on).

In Ado.Net, we perform our queries or procedures using SqlDataReader, SqlCommand etc. objects. Dapper takes the burden of writing these objects from us.

We can do our filtering by using generic and extension methods. By writing less code, we can execute our queries in a short time and convert them to the type we want. The biggest feature is it works very fast speed and very close to Ado.Net speed.

Create Business Layer

After that, We should create Create “Repositories” and IDiscountRepository interface.

Repositories Folder

Add Interface — IDiscountRepository

namespace Discount.API.Repositories.Interfaces

{

public interface IDiscountRepository

{

Task<Coupon> GetDiscount(string productName); Task<bool> CreateDiscount(Coupon coupon);

Task<bool> UpdateDiscount(Coupon coupon);

Task<bool> DeleteDiscount(string productName);

}

}

After that, we can implement this interface with using NpgsqlConnection objects.

Create Repository — DiscountRepository

namespace Basket.API.Repositories

{

public class DiscountRepository : IDiscountRepository

{

private readonly IConfiguration _configuration; public DiscountRepository(IConfiguration configuration)

{

_configuration = configuration ?? throw new ArgumentNullException(nameof(configuration));

}

{

using var connection = new NpgsqlConnection(_configuration.GetValue<string>(“DatabaseSettings:ConnectionString”));



var coupon = await connection.QueryFirstOrDefaultAsync<Coupon>

(“SELECT * FROM Coupon WHERE ProductName =



if (coupon == null)

return new Coupon { ProductName = “No Discount”, Amount = 0, Description = “No Discount Desc” };

return coupon;

} public async Task GetDiscount(string productName)using var connection = new NpgsqlConnection(_configuration.GetValue (“DatabaseSettings:ConnectionString”));var coupon = await connection.QueryFirstOrDefaultAsync (“SELECT * FROM Coupon WHERE ProductName = @ProductName ”, new { ProductName = productName });if (coupon == null)return new Coupon { ProductName = “No Discount”, Amount = 0, Description = “No Discount Desc” };return coupon; public async Task<bool> CreateDiscount(Coupon coupon)

{

using var connection = new NpgsqlConnection(_configuration.GetValue<string>(“DatabaseSettings:ConnectionString”));

await connection.ExecuteAsync

(“INSERT INTO Coupon (ProductName, Description, Amount) VALUES (@Description,

new { ProductName = coupon.ProductName, Description = coupon.Description, Amount = coupon.Amount }); var affected =await connection.ExecuteAsync(“INSERT INTO Coupon (ProductName, Description, Amount) VALUES ( @ProductName @Amount )”,new { ProductName = coupon.ProductName, Description = coupon.Description, Amount = coupon.Amount }); if (affected == 0)

return false; return true;

} public async Task<bool> UpdateDiscount(Coupon coupon)

{

using var connection = new NpgsqlConnection(_configuration.GetValue<string>(“DatabaseSettings:ConnectionString”));

(“UPDATE Coupon SET ProductName=

new { ProductName = coupon.ProductName, Description = coupon.Description, Amount = coupon.Amount, Id = coupon.Id }); var affected = await connection.ExecuteAsync(“UPDATE Coupon SET ProductName= @ProductName , Description = @Description , Amount = @Amount WHERE Id = @Id ”,new { ProductName = coupon.ProductName, Description = coupon.Description, Amount = coupon.Amount, Id = coupon.Id }); if (affected == 0)

return false; return true;

} public async Task<bool> DeleteDiscount(string productName)

{

using var connection = new NpgsqlConnection(_configuration.GetValue<string>(“DatabaseSettings:ConnectionString”));

new { ProductName = productName }); var affected = await connection.ExecuteAsync(“DELETE FROM Coupon WHERE ProductName = @ProductName ”,new { ProductName = productName }); if (affected == 0)

return false; return true;

}

}

}

Basically we are using “NpgsqlConnection” object as a postgresql connection. This will create connection for us with using connection string. After that with using “connection” object and methods, we are using Dapper sql commands. This will be the fastest way to use micro-orm to retrieve data from databases.

Create DiscountController Class for Discount.API Microservice

First of all, We should create DiscountController into Controller class.

Controller + Startup.cs

[ApiController]

[Route(“api/v1/[controller]”)]

public class DiscountController : ControllerBase

{

private readonly IDiscountRepository _repository; public DiscountController(IDiscountRepository repository)

{

_repository = repository ?? throw new ArgumentNullException(nameof(repository));

}



[HttpGet(“{productName}”, Name = “GetDiscount”)]

[ProducesResponseType(typeof(Coupon), (int)HttpStatusCode.OK)]

public async Task<ActionResult<Coupon>> GetDiscount(string productName)

{

var discount = await _repository.GetDiscount(productName);

return Ok(discount);

} [HttpPost]

[ProducesResponseType(typeof(Coupon), (int)HttpStatusCode.OK)]

public async Task<ActionResult<Coupon>> CreateDiscount([FromBody] Coupon coupon)

{

await _repository.CreateDiscount(coupon);

return CreatedAtRoute(“GetDiscount”, new { productName = coupon.ProductName }, coupon);

} [HttpPut]

[ProducesResponseType(typeof(Coupon), (int)HttpStatusCode.OK)]

public async Task<ActionResult<Coupon>> UpdateDiscount([FromBody] Coupon coupon)

{

return Ok(await _repository.UpdateDiscount(coupon));

} [HttpDelete(“{productName}”, Name = “DeleteDiscount”)]

[ProducesResponseType(typeof(void), (int)HttpStatusCode.OK)]

public async Task<ActionResult<bool>> DeleteDiscount(string productName)

{

return Ok(await _repository.DeleteDiscount(productName));

}

}

we have injected IDiscountRepository object and use this object when exposing apis.

You can see that we have exposed crud api methods over the DiscountController.

Also you can see the anotations.

ProducesResponseType — provide to restrictions on api methods. produce only including types of objects.

Route — provide to define custom routes. Mostly using if you have one more the same http method.

httpget/put/post — send http methods.

Test and Run Discount Microservice

We are going to Test and Run Discount Microservice. Now the Discount microservice Web API application ready to run.

Before running the application, configure the debug profile;

Right Click the project File and Select to Debug section.

Change Launch browser to swagger

Change the App URL to http://localhost:5002

Hit F5 on Discount.API project.

Exposed the Product APIs in our Catalog Microservices, you can test it over the Swagger GUI.

You can also test it over the Postman as below way.

http://localhost:5002/swagger/index.html

See CRUD operations on Swagger

— -

Set productName

productName — IPhone X

productName — Samsung 10

Get Success :

{

“id”: 1,

“productName”: “IPhone X”,

“description”: “IPhone Discount”,

“value”: 150

}



Create

{

“productName”: “Huawei Plus”,

“description”: “test new product”,

“value”: 550

} Update

{

“productName”: “Huawei Plus”,

“description”: “test update”,

“value”: 200

} Delete

productName — IPhone X

productName — Samsung 10

productName — Huawei Plus

As you can see that, we have test our Discount microservices is working fine.