C# API with Injected Service and Entity Framework

This application is a Calculator service injected into our API

ERD

An Entity Relationship Diagram shows our database structure. Generated using app.diagrams.net. This is a simple one that shows the Entities and the links between them.

• Further Reading on W3Schools

Branches

Main, OneToMany, ManyToMany, Repository, Validation increase in complexity.

List branches: git branch Change branch: git checkout <<branchname>>

Setup

• Remove or rename the appsettings.Example.json so that you have an appsettings.json, appsettings.Development.json file in the root of the workshop.wwwapi project which contains your NEON credentials:

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft.AspNetCore": "Warning"
    }
  },
  "AllowedHosts": "*",
  "ConnectionStrings": {
    "DefaultConnectionString": "Host=URL; Database=neondb; Username=neondb_owner; Password=PASSWORD;"
  }
}

• Note the .gitignore file in the root of the project which prevents the build directories being uploaded:

*/**/bin/Debug
*/**/bin/Release
*/**/obj/Debug
*/**/obj/Release
/workshop.wwwapi/appsettings.json
/workshop.wwwapi/appsettings.Development.json

Dependencies Installed

You'll need all of these which have already been installed in this project:

• Install-Package Scalar.AspNetCore provides a /scalar endpoint
• Install-Package Swashbuckle.AspNetCore provides a /swagger endpoint
• Install-Package Microsoft.EntityFrameworkCore
• Install-Package Microsoft.EntityFrameworkCore.Tools
• Install-Package Microsoft.EntityFrameworkCore.Design
• Install-Package NpgSql.EntityFrameworkCore.PostgreSql

Change the Program.cs

builder.Services.AddDbContext<DataContext>(options => {
    options.UseNpgsql(builder.Configuration.GetConnectionString("DefaultConnectionString"));
    options.LogTo(message => Debug.WriteLine(message));

});

Run a Migration

In the Package Manager Console you can run:

• add-migration First to create a migration
• update-database to apply to a db

Repository Layer

So this isn't ideal at the moment. I'm creating a Repository Layer for every Entity in my Database.

PersonSubjects Table

The join between the Person and Subjects is done via the PersonSubjects table. Note as I haven't written and endpoint for this, I used sql to insert some records:

INSERT INTO "Subjects" ("Name") VALUES
  ('Mathematics'),
  ('Nautical Studies'),
  ('Science'),
  ('Spanish'),
  ('German'),
  ('French'),
  ('Dutch'),
  ('Norwegian');



INSERT INTO "PersonSubjects" ("PersonId", "SubjectId", "CreationDate") VALUES (1, 3, CURRENT_TIMESTAMP);
INSERT INTO "PersonSubjects" ("PersonId", "SubjectId", "CreationDate") VALUES (1, 1, CURRENT_TIMESTAMP);
INSERT INTO "PersonSubjects" ("PersonId", "SubjectId", "CreationDate") VALUES (1, 6, CURRENT_TIMESTAMP);
INSERT INTO "PersonSubjects" ("PersonId", "SubjectId", "CreationDate") VALUES (1, 7, CURRENT_TIMESTAMP);

Validation

Install-Package FluentValidation
Install-Package FluentValidation.DependencyInjectionExtensions