.NET REST API

Question 1

What is the Microsoft Framework used for relational database interaction?

Answer 1

Entity Framework Core

Question 2

What are the CLI commands used for building a .Net Rest Api

Answer 2

dotnet new sln
dotnet new webapi -o [projname]
dotnet new classlib -f [framework] -o [name]
dotnet sln add [path]

Question 3

What CLI command is used to add references to neighbouring class libraries?

Answer 3

dotnet add app/app.csproj reference lib/lib.csproj

Question 4

What are the main classlibs (aside from the main webapi) required for a rest api?

Answer 4

data -> for database interaction
services -> expressive methods for webapi use
test -> for testing
Class libs are a great way to seperate concerns and keep a clean working directory.

Question 5

Which class defines the configuration & services for the REST API?

Answer 5

Startup.cs

Question 6

Which NuGet packages are required to be added

Answer 6

Add the Microsoft.EntityFrameworkCore & the Microsoft.EntityFrameworkCore.Design. Also the NewtonSoft.Json package is useful.

Question 7

How do you define a data Model

Answer 7

Create a class (in the data classlib /Models/) that contains the layout of each table in your DB, with each table being defined as a field. Each field that is another class requires another model.

Question 8

What is a database context

Answer 8

A database context defines the context, or overall shape, of the database. It is a class that inherits from DbContext (EF CORE) and should have the following shapes

public GoodbooksDbContext() { }
public GoodbooksDbContext(DbContextOptions options) : base(options) { }
public virtual DbSet PluralOfModelName { get; set; }

Question 9

How do you inject the EF CORE DbContext into the services.

Answer 9

In the ConfigureServices Method in Startup.cs:
services.AddDbContext(opts => {
opts.EnableDetailedErrors();
// setup database preference e.g. Postgres
});

Question 10

How do you setup a service

Answer 10

Define an interface with the methods required (i.e. what you want to do with the database), and then implement that interface

Question 11

How do you inject the EF Core database context into a service?

Answer 11

Create a readonly field, define an instance in the constructor parameters, then in the body assign the parameter to the readonly field.

private readonly GoodbooksDbContext _db;
public BookService(GoodbooksDbContext db)
{
  _db = db;
}

Question 12

What are the standard EF Core database Methods for CRUD operations

Answer 12

Create -> _db.Add()
Read -> _db.Find() / _db.ToList()
Update -> _db.Update()
Delete -> _db.Delete()

Question 13

What EF Core method must be invoked on any non-read CRUD operation

Answer 13

_db.SaveChanges()

Question 14

Where should the service be injected?

Answer 14

Into any controller class that uses it/ handles any http request. Inject using the interface of the service.

Question 15

Where are the controllers located?

Answer 15

In the main web API project. They handle requests that come in.

Question 16

What attributes can be given to controllers

Answer 16

[HttpGet(“/api/hello/”)] // Get method
[HttpPost(“/api/hello/”)] // Post method
[HttpPatch(“/api/hello/{id}”)] // Patch method
[HttpDelete(“/api/hello/{id}”)] // Delete Method
[Route(“{controller}/[action]”)] // if MVC
[Route(“api/[controller]”)] // to class
[ApiController] // to class

Question 17

When does a project need to reference a class library

Answer 17

If it uses the namespace. Add a reference with the dotnet CLI, or right click the project in Visual Studio.

Question 18

What is the return type of a webapi controller?

Answer 18

ActionResult

Question 19

What methods can be used to return data and status codes from a controller

Answer 19

OK(data); // status 200
Created(url, data); // status 201
NoContent(); // status 204
BadRequest(); // status 400
Unauthorized(); // status 401
NotFound(); // status 404

Question 20

What is a Makefile?

Answer 20

A makefile can define command line executions within a .NET project.

Question 21

What Makefile definitions should be used?

Answer 21

Project Variables

PROJECT_NAME ?= Goodbooks

.PHONY: migrations db

migrations:
cd && dotnet ef –startup-project migrations add $(mname) && cd ..
db:
cd && dotnet ef –startup-project database update && cd ..

— IN THE COMMAND LINE –
make migrations mname=Initial
make db

Question 22

How is a connection to a postgres database initialised?

Answer 22

In the Db context service definition in the Startup class, use the options method UseNpgsql.

opts.UseNpgsql(Configuration.GetConnectionString(“projname.dev”));

Then define the connection string in the appsettings.json file:
“projname.dev”: “Host=localhost;Port=5432; Username=username; Password=password; Database=projectname.dev”

Question 23

How is a database model field made nullable?

Answer 23

Add a question mark after the datatype -> string?

Question 24

When should migrations and database update be run?

Answer 24

Any time the database schema is updated.

Question 25

What Field & attribute can be used to define a relations in a database model?

Answer 25

Include the [ForeignKey()] for the relational field and reference a shared ID as a field.