The next section

Skeleton

a tiny implementation of system that performs a small end to end function ⇒ Final architecture, linking together the main architectural components ⇒ evolve in parallel

Learning goals

Creating the .Net app project

linux: ls window: dir the path of the project in my laptop:

D:\Code\.Net\Code\DatingApp

the commands:

mkdir DatingApp
cd DatingApp

dotnet cli:

dotnet --info

dotnet new list

dotnet new webapi -h

Note: using the controller

dotnet new list

start

dotnet new sln

dotnet new webapi -controllers -n API

-n: name

dotnet sln -h

dotnet sln add API

dotnet sln list

using VSCode: setting(ctrl + ,) ⇒ open settings(json) on the right side bar ⇒ justify your setting go to extentions store ⇒ download C# dev kit, C#, .NET Install Tool, NuGet Gallery, material icons

start

cd API && dotnet run

dotnet run --launch-profile https

if have a warning ⇒ go to

D:\Code\.Net\Code\DatingApp\API\Properties\launchSettings.json

and change remove http, keep https such as:

{
  "$schema": "https://json.schemastore.org/launchsettings.json",
  "profiles": {
    "https": {
      "commandName": "Project",
      "dotnetRunMessages": true,
      "launchBrowser": false,
      "applicationUrl": "https://localhost:5000;",
      "environmentVariables": {
        "ASPNETCORE_ENVIRONMENT": "Development"
      }
    }
  }
}

Go to file to see the route, end-point, httpget:

D:\Code\.Net\Code\DatingApp\API\Controllers\WeatherForecastController.cs

And this file has the site to check API work correctly

D:\Code\.Net\Code\DatingApp\API\API.http

Changes this for development

D:\Code\.Net\Code\DatingApp\API\appsettings.Development.json

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft.AspNetCore": "Information"
    }
  }
}

Changes this file, not using OpenAI for document

D:\Code\.Net\Code\DatingApp\API\Program.cs

var builder = WebApplication.CreateBuilder(args);
// Add services to the container.
builder.Services.AddControllers();
// Learn more about configuring OpenAPI at https://aka.ms/aspnet/openapi
var app = builder.Build();
// Configure the HTTP request pipeline.
app.UseAuthorization();
app.MapControllers();
app.Run();

**Some dotnet for cert for https when the site has warning about:

Your connection to this site isn't secure
 
Don't enter any sensitive information on this site (for example, passwords or credit cards). It could be stolen by attackers.
 
You have chosen to turn off security warnings for this site. [Turn on warnings](edge://page-info/#)

dotnet dev-certs commands:

—help

dotnet dev-certs https -h

—check

dotnet dev-certs https -c

—trust

dotnet dev-certs https -t

—clean

dotnet dev-certs https --clean

if it doesn’t work, you would try to restart the browser or:

dotnet dev-certs https --clean 
dotnet dev-certs https --trust

Entities - Class, OOP, Table, Property

*In API.csproj

<ImplicitUsings>enable</ImplicitUsings>

This help us auto define global to reduce the source code, so we can delete using system on classes where have them.*

typing prop and ‘tab’ in class to have template #Note Compare

Tổng hợp 6 cách khai báo thuộc tính Id:

1. public string? Id { get; set; }

Nullable: Cho phép null
Default: null
Use case: Khi cần phân biệt “chưa có” vs “rỗng” 2. public string Id { get; set; } = string.Empty;
Non-nullable: Không cho phép null
Default: ""
Use case: Đảm bảo luôn có string, tránh null exception 3. public required string Id { get; set; }
Mandatory: Bắt buộc khởi tạo (C# 11+)
Compile-time: Compiler check
Use case: Khi Id là required field 4. public string Id { get; set; } = Guid.NewGuid().ToString();
Auto-generated: Tự động tạo unique ID
Performance cost: Tạo GUID mỗi object
Use case: Cần unique identifier 5. public string Id { get; set; } = "";
Empty string: Giống string.Empty
Literal: Hard-coded empty
Use case: Tương đương option 2 6. public string Id { get; set; } = Empty.ToString(); ❌
Lỗi cú pháp: Empty không tồn tại
Không sử dụng được

So sánh toàn diện:

Tiêu chí	1 (`string?`)	2 (`string.Empty`)	3 (`required`)	4 (`Guid`)	5 (`""`)
Null Safety	❌ Cần check	✅ An toàn	✅ An toàn	✅ An toàn	✅ An toàn
Performance	✅ Tốt	✅ Tốt	✅ Tốt	❌ Chi phí GUID	✅ Tốt
Flexibility	✅ Cao	⚠️ Trung bình	⚠️ Hạn chế	❌ Thấp	⚠️ Trung bình
Security	❌ Runtime risk	✅ An toàn	✅ An toàn	✅ Unique	✅ An toàn
Maintainability	❌ Phức tạp	✅ Đơn giản	✅ Rõ ràng	✅ Tự động	✅ Đơn giản

🎯 Khuyến nghị chọn:

Cho Entity/Domain Model:

public required string Id { get; set; }  // Option #3

Lý do: Bắt buộc khởi tạo, compile-time safety Cho DTO/API Model:

public string Id { get; set; } = string.Empty;  // Option #2

Lý do: An toàn, không cần validation phức tạp Cho Auto-generated ID:

public string Id { get; set; } = Guid.NewGuid().ToString();  // Option #4

Lý do: Unique, phù hợp cho primary key ❌ Tránh:

Option #1: Dễ gây NullReferenceException
Option #6: Lỗi cú pháp Kết luận: Chọn Option 3 (required) cho hầu hết trường hợp - an toàn nhất và rõ ràng nhất.

An Object Relational Mapper (ORM) Translate code into SQL commands that update the table in database -CRUD

Querying
Change Tracking
Saving
Concurrency
Transactions
Caching
Built-in conventions
Configurations
Migrations #dotnet Download Nuget: Microsoft.EntityFrameworkCore.Design @Microsoft Microsoft.EntityFrameworkCore.Sqlite @Microsoft

dotnet restore

Folder Data in API

using Microsoft.EntityFrameworkCore; Class AppDbContext : DbContext typing ‘ctor’ to have constructor

Command to setup dotnet ef: check:

dotnet tool list -g

EF:

dotnet tool install -g dotnet-ef

dotnet ef

dotnet ef migrations -h

dotnet ef migrations add InitialCreate -o Data/Migrations

Update

dotnet ef database update

Bugs của extension bản mới =))

Bug trong extension alexcvzz.vscode-sqlite
SQLite 3.41.0+ không support double quotes cho string literals
Extension dùng type="table" thay vì type='table'

Fix options: 1. Manual patch (Windows path):

%USERPROFILE%\.vscode\extensions\alexcvzz.vscode-sqlite-*\dist\extension.js

Tìm và thay: javascript

WHERE (type=\"table\" OR type=\"view\")
// thành:
WHERE (type='table' OR type='view')

2. Alternative extensions:

SQLite Viewer (qwtel.sqlite-viewer)
vscode-sqlite3-editor

3. Workaround:

Dùng SQLite CLI: sqlite3 dating.db
DB Browser for SQLite (standalone app)

Security note: Editing extension files có thể bị overwrite khi update. Alternative extension là safer approach.

Recommendation: Switch sang SQLite Viewer extension để tránh compatibility issues với SQLite versions mới. -⇒ Được thì có thể sửa và dùng, sau đó xóa

dotnet watch

Sync:

namespace API.Controllers
{
    [Route("api/[controller]")] // localhost:5001/api/members
    [ApiController]
    public class MembersController(AppDbContext context) : ControllerBase
    {
        [HttpGet]
        public ActionResult<IReadOnlyList<AppUser>> GetMembers()
        {
            var members = context.Users.ToList();
            return Ok(members); // Returns a list of members
        }
        [HttpGet("{id}")] // localhost:5001/api/members/{id}
        public ActionResult<AppUser> GetMember(string id)
        {
            var member = context.Users.Find(id);
            if (member == null)
            {
                return NotFound(); // Returns 404 if member not found
            }
            return Ok(member); // Returns the member details
        }
    }
}

Async:

public class MembersController(AppDbContext context) : ControllerBase
    {
        [HttpGet]
        public async Task<ActionResult<IReadOnlyList<AppUser>>> GetMembers()
        {
            var members = await context.Users.ToListAsync();
            return Ok(members); // Returns a list of members
        }
        [HttpGet("{id}")] // localhost:5001/api/members/{id}
        public async Task<ActionResult<AppUser>> GetMember(string id)
        {
            var member = await context.Users.FindAsync(id);
            if (member == null)
            {
                return NotFound(); // Returns 404 if member not found
            }
            return Ok(member); // Returns the member details
        }
    }

Template for gitignore

dotnet new gitignore

Vuong-Dat Notes

Explorer

Day 1 section 2