In software development, error handling is a critical component. The way a software handles errors, no matter how minor or large, can have a significant impact on how well it functions for users. One neat error-handling technique in the world of.NET Core is dubbed "global exception handling using custom middleware." It's like having a superhero for your code who finds bugs and fixes them all in one location, strengthening and enhancing the dependability of your application.

Comprehending Global Exception Management
In most.NET Core programs, try-catch blocks are used to encircle any code that may potentially cause issues. However, if we do this everywhere, our code may become jumbled and repetitious. This is resolved by global exception handling, which establishes a central system that detects faults wherever they occur.

Personalized Middleware
In.NET Core, the phrase "middleware" refers to a fancy manner of handling requests and responses in a web application. Custom middleware expands on this concept. It allows us to add custom code to the process, such as additional support to handle problems. This makes our code easier to read and more orderly.

Putting Custom Exception Middleware in Place
These steps must be followed in order to configure global exception handling in.NET Core utilizing custom middleware.
1. Create Custom Middleware: Write a unique piece of code, or middleware, to detect application issues.

public class ExceptionMiddleware
{
    private readonly RequestDelegate _next;

    public ExceptionMiddleware(RequestDelegate next)
    {
        _next = next;
    }

    public async Task InvokeAsync(HttpContext context)
    {
        try
        {
            await _next(context);
        }
        catch (Exception ex)
        {
            // Here we handle the error
            await HandleExceptionAsync(context, ex);
        }
    }

    private async Task HandleExceptionAsync(HttpContext context, Exception ex)
    {
        // Handle the error and let the user know
        // Respond with a message saying something went wrong
        context.Response.ContentType = "application/json";
        context.Response.StatusCode = (int)HttpStatusCode.InternalServerError;
        await context.Response.WriteAsync("An unexpected error occurred.");
    }
}

2. Register Middleware: Tell the application to use our special middleware to handle errors.
public void Configure(IApplicationBuilder app)
{
    app.UseMiddleware<ExceptionMiddleware>();
    // More configurations can go here...
}

Custom Exception Middleware's advantages
In.NET Core, there are several excellent benefits to using custom middleware for global exception handling.

Centralized Management of Errors
Because all error handling is done in one location, managing and comprehending the code is made simpler. Consistent Error Responses: Ensure that the user always receives the same type of message when something goes wrong, so that both they and us can identify the issue. More robust applications Our apps become more dependable and capable of handling issues without crashing when they handle errors gracefully.

In order to comprehend and improve the performance of their applications, developers can benefit greatly from the use of monitoring and profiling in software development and maintenance. Let's investigate profiling and monitoring inside the framework of web apps, with an emphasis on Angular applications specifically.

Observing
Monitoring of Angular Performance

Angular Performance Explorer is an integrated tool that comes with Angular.

Some popular tools include.

1. Explorer of Angular Performance
Angular Performance Explorer is an integrated tool that comes with Angular. This tool gives you information on how well Angular components, directives, and services are performing. It can be accessed using the developer tools in your browser. It's also useful to you.

Examine how long the lifecycle hooks for each component take.
Examine the cycles of change detection and locate any possible bottlenecks.
Track the duration of each component's rendering.

To access the Angular Performance Explorer

Open Chrome DevTools (F12 or right-click and select "Inspect").
Navigate to the "Performance" tab.
Click on the "Angular" sub-tab.

2. Google Chrome DevTools

Google Chrome DevTools offers a powerful set of tools for monitoring and debugging Angular applications. The "Performance" tab within DevTools allows you to.

Record and analyze runtime performance.
Identify CPU and memory usage.
Understand the timeline of events during a user interaction or page load.

To use Chrome DevTools for Angular performance monitoring.

Open Chrome DevTools (F12 or right-click and select "Inspect").
Navigate to the "Performance" tab.
Record a performance profile by clicking the red circle.
Perform the desired actions in your Angular application.
Stop the recording by clicking the red square.

3. Real User Monitoring (RUM) Tools

Consider using Real User Monitoring (RUM) tools such as New Relic, Datadog, or others. These tools provide insights into how real users are experiencing your Angular application, including page load times, AJAX requests, and user interactions. Integrating RUM tools typically involves adding a monitoring script to your application, which then sends performance data to the chosen monitoring service.

Logging and Error Tracking
Logging and error tracking are essential components of any application's monitoring and maintenance strategy. They help developers identify issues, troubleshoot problems, and improve overall application stability. In the context of Angular applications, here are some strategies for logging and error tracking:
Logging in Angular

1. Console Logging

Angular applications can utilize standard console logging for debugging purposes. You can use console.log(), console. warn(), and console.error() statements to output information to the browser's console.

// Example component with console logging
@Component({
selector: 'app-example',
template: '<p>Example Component</p>',
})
export class ExampleComponent implements OnInit {
ngOnInit() {
console.log('Component initialized');
}
}

3. Angular Logging Services

For more sophisticated logging, consider using third-party logging libraries or services. Popular ones include.

Angular Logger Service: A custom logging service that can be injected into Angular components and services.
Ngx Logger: A configurable logging service for Angular applications.

Error Tracking

1. Global Error Handling
Implement a global error handler to catch unhandled errors throughout your Angular application. You can use the ErrorHandler service provided by Angular to customize error handling.
// Example global error handler
@Injectable()
export class GlobalErrorHandler implements ErrorHandler {
handleError(error: any): void {
// Handle the error (e.g., log it, send to an error tracking service)
console.error('Global error handler:', error);
}
}

In your AppModule, provide this error handler.
@NgModule({
providers: [
{ provide: ErrorHandler, useClass: GlobalErrorHandler },
],
})
export class AppModule { }

2. Third-Party Error Tracking Services
Integrate third-party error tracking services to monitor and receive alerts about errors in your application. Popular services include.

Sentry: A platform for real-time error tracking and monitoring.
Rollbar: A cloud-based error tracking and monitoring service.
Bugsnag: A tool for detecting and diagnosing application errors.

To integrate Sentry, for example, you would typically install the Sentry package and configure it in your Angular application.

npm install @sentry/angular @sentry/tracing

// Import and configure Sentry in your AppModule
import { SentryModule } from '@sentry/angular';
import { Integrations } from '@sentry/tracing';

Sentry.init({
dsn: 'YOUR_DSN',
integrations: [
new Integrations.BrowserTracing(),
],
});

@NgModule({
imports: [SentryModule],
})
export class AppModule { }

Logging and Error Tracking Best Practices

Environment-Specific Configuration: Configure logging and error tracking differently based on the environment (development, staging, production). For example, you might want more verbose logging in development but less in production.
Include Context Information: When logging or tracking errors, include relevant context information such as user details, browser version, and the application's state.
Security Considerations: Ensure that sensitive information is not exposed in logs or error reports. Be mindful of data privacy and security concerns.
Regular Monitoring: Regularly review logs and error reports to identify patterns, trends, and potential areas for optimization.
Continuous Improvement: Iteratively improve logging and error tracking based on the insights gained from monitoring and analysis.

Profiling
Profiling is the process of analyzing and measuring various aspects of a program's performance to identify bottlenecks, optimize resource usage, and improve overall efficiency. In the context of Angular applications, profiling can help developers understand how the application behaves and where performance improvements can be made. Here are some profiling techniques and tools for Angular.
Angular Profiler

Angular itself provides a built-in profiler that can be enabled using the Angular CLI. This profiler offers insights into change detection, rendering, and other Angular-specific metrics.

To enable the Angular profiler, you can use the following command when starting your Angular application.
ng serve --profile

This enables the Angular profiler, which provides additional information about change detection, rendering, and other performance-related metrics.
Chrome DevTools

1. Performance Tab
Chrome DevTools is a powerful set of tools for debugging and profiling web applications. The "Performance" tab in Chrome DevTools allows you to record and analyze runtime performance, CPU usage, memory allocation, and other metrics.

To use the Performance tab.

• Open Chrome DevTools (F12 or right-click and select "Inspect").
• Navigate to the "Performance" tab.
• Record a performance profile by clicking the red circle.
• Perform the desired actions in your Angular application.
• Stop the recording by clicking the red square.

2. Memory Tab
The "Memory" tab in Chrome DevTools helps you analyze memory usage in your application. It can be useful for identifying memory leaks and optimizing memory consumption.
Augury

Angury is a Chrome and Firefox DevTools extension specifically designed for debugging and profiling Angular applications. It provides additional insights into the structure, state, and performance of your Angular application.

To use Augury

Install the Augury extension from the Chrome Web Store or Firefox Add-ons.
Open Chrome DevTools or Firefox Developer Tools.
Navigate to the "Augury" tab.

Web Performance Testing

1. Lighthouse
Lighthouse is an open-source, automated tool for improving the quality of web pages. It has audits for performance, accessibility, progressive web apps, SEO, and more.

You can run Lighthouse from the Chrome DevTools or use the Lighthouse CLI to perform audits on your Angular application.
# Install Lighthouse globally
npm install -g lighthouse

# Run Lighthouse on your Angular app
lighthouse http://localhost:4200

Webpack Bundle Analyzer
If you want to analyze the size of your application bundles, you can use tools like Webpack Bundle Analyzer. This tool visualizes the size of your bundles and dependencies, helping you identify areas for optimization.
# Install Webpack Bundle Analyzer
npm install --save-dev webpack-bundle-analyzer

Then, add a script in your package.json to run the analyzer
"scripts": {
"analyze": "webpack-bundle-analyzer dist/your-app-name/stats.json"
}

Run the script after building your Angular application.
npm run build -- --prod
npm run analyze

Profiling tools and techniques are essential for identifying performance bottlenecks and optimizing Angular applications. Regularly profile your application, especially during development and before deploying to production, to ensure optimal performance.

Best Practices
1. Code Splitting: Implement code splitting to reduce the initial load time of your Angular application. This involves breaking your application into smaller modules that are loaded on demand.
2. Lazy Loading: Take advantage of Angular's lazy loading feature to load modules only when they are needed, improving the initial page load time.
3. Optimize Change Detection: Angular's change detection can be resource-intensive. Optimize it by using the OnPush change detection strategy and avoiding unnecessary triggers.
4. Bundle Optimization: Configure your build tools (such as Angular CLI or Webpack) to optimize and minify your application bundles for production. This reduces the overall size of your application, improving load times.
5. Caching Strategies: Implement proper caching strategies for assets and API calls to reduce the number of network requests and improve the overall performance of your application.
6. Performance Budgets: Set performance budgets to establish acceptable thresholds for metrics like page load time, bundle size, and other critical performance indicators.
7. Continuous Monitoring: Implement continuous monitoring practices to catch performance issues early in development and production. This can include automated tests, performance regression testing, and monitoring tools integrated into your CI/CD pipeline.

By combining monitoring and profiling techniques with best practices, you can ensure that your Angular application is not only performant but also maintainable and scalable. Regularly revisit and adjust your strategies as your application evolves to keep it optimized over time.

I'll go over how to construct a.NET MAUI Popup page with Visual Studio 2022 in this tutorial. Operating systems offer a mechanism to display a message and request a response from the user. These alerts are usually restricted in terms of the content a developer can provide as well as the layout and appearance. Popups are a very common way of presenting information to a user that relates to their current task.

Important

• An exception will be raised when attempting to display your Popup if the code underlying the file is not generated concurrently with the call to InitializeComponent.
• Only a Page or an implementation that derives from a Page may display a Popup.

Take note

• It will finish and return to the calling thread before the operating system dismisses the Popup from the screen since Close() is a fire-and-forget procedure. Use CloseAsync() in its place if you need to stop your code from running until the operating system has removed the Popup from the screen.
• The ResultWhenUserTapsOutsideOfPopup property allows you to modify the value that is returned in order to handle tapping outside of a Popup while also waiting for the outcome.
• Make sure to specify the ApplyToDerivedTypes property on the Style definition when establishing a style that targets Popup if you want it to apply to custom popups, such as the SimplePopup example.

Step 1: Open Visual Studio 2022, create a new project, and choose the app option under the multiplatform section on the left side panel. Next, Select the.NET MAUI App with C# option and press the continue button.

Step 2: You must choose the.Net framework version 6.0 and press the proceed button on the following screen.

Step 3: Click the Create button after entering your location, the name of your project, and the name of your solution on the following screen.

Step 4: The NuGet Package CommunityToolkit needs to be downloaded.The MauiProgram.cs file needs to be configured for Maui and CommunityToolkit.
The Community Toolkit can be downloaded using NuGet Package Manager.

dotnet add package CommunityToolkit.Maui --version 7.0.1

2. Configure CommunityToolKit in MauiProgram.cs.
using Microsoft.Extensions.Logging;
using CommunityToolkit.Maui;

namespace Popup
{
    public static class MauiProgram
    {
        public static MauiApp CreateMauiApp()
        {
            var builder = MauiApp.CreateBuilder();

            builder
                .UseMauiApp<App>()
                .UseMauiCommunityToolkit()
                .ConfigureFonts(fonts =>
                {
                    fonts.AddFont("OpenSans-Regular.ttf", "OpenSansRegular");
                    fonts.AddFont("OpenSans-Semibold.ttf", "OpenSansSemibold");
                });

#if DEBUG
            builder.Logging.AddDebug();
#endif

            return builder.Build();
        }
    }
}

Step 5. The next step is to create the new content page and define the Community Popup view In order to use the toolkit in XAML the following xmlns need to be added to your page or view.
xmlns:toolkit="http://schemas.microsoft.com/dotnet/2022/maui/toolkit"

Therefore, the following
<?xml version="1.0" encoding="utf-8" ?>
<mct:Popup xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
           xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
           xmlns:mct="clr-namespace:CommunityToolkit.Maui.Views;assembly=CommunityToolkit.Maui"
           x:Class="Popup.MainPage"
           CanBeDismissedByTappingOutsideOfPopup="False"
           Size="300, 300">

    <Border VerticalOptions="CenterAndExpand"
            HorizontalOptions="CenterAndExpand"
            Stroke="White"
            StrokeThickness="1"
            StrokeShape="RoundRectangle 10">

        <VerticalStackLayout VerticalOptions="CenterAndExpand" Spacing="20">

            <Label Text="Welcome to .NET MAUI!"
                   VerticalOptions="Center"
                   HorizontalOptions="Center" />

            <Button Text="Close" Clicked="Button_Clicked" />

        </VerticalStackLayout>

    </Border>
</mct:Popup>

Step 6. The next step is to call the Popup from Main Page event or initialization and A Popup can only be displayed from a Page or an implementation inheriting from Page.
using CommunityToolkit.Maui.Views;

namespace Popup
{
    public partial class FirstPage : ContentPage
    {
        public FirstPage()
        {
            InitializeComponent();
        }

        private void OnCounterClicked(object sender, EventArgs e)
        {
            this.ShowPopup(new MainPage());
        }
    }
}

Output screen

With any luck, this post has provided you with enough knowledge to use viewmodel to design an MAUI collection view and execute the application on both iOS and Android. Please feel free to leave a comment if you would like me to go into further detail on anything I've covered in this post.

In modern web development, making HTTP requests is a fundamental aspect of building robust and dynamic applications. In the .NET Core ecosystem, the HttpClient class has long been the go-to choice for sending HTTP requests. However, as applications grow in complexity, managing instances of HttpClient can become a challenge. This is where the HttpClientFactory in .NET Core comes to the rescue, providing a more efficient and scalable solution for handling HTTP requests.

HttpClient: What is it?
Developers can send and receive HTTP requests and responses by using the HttpClient class in the System.Net.Http namespace. Because of its portability and ability to establish and manage HTTP connections, it can be used in situations where several requests are sent to the same endpoint.

This is a simple example of sending a GET request using HttpClient.

using System;
using System.Net.Http;
using System.Threading.Tasks;

class Program
{
    static async Task Main()
    {
        using (HttpClient client = new HttpClient())
        {
            string url = "https://api.example.com/data";
            HttpResponseMessage response = await client.GetAsync(url);

            if (response.IsSuccessStatusCode)
            {
                string result = await response.Content.ReadAsStringAsync();
                Console.WriteLine(result);
            }
        }
    }
}

Even if this method functions, it's not the most effective for handling several requests at once. It is typically not advised to create a new instance of HttpClient for each request as this can cause problems such as socket exhaustion.

HttpClientFactory: What is it?
The HttpClientFactory is part of the Microsoft.Extensions.In order to overcome the problems of manually managing HttpClient instances, the http package was established. It offers a more organized and scalable method for setting up, configuring, and administering HttpClient instances.

Principal Advantages of Using HttpClientFactory

• Lifetime Management: It manages the HttpClient instances' lifecycle, reusing existing connections to avoid problems like socket exhaustion.
• Configuration: HttpClientFactory makes it easier to manage many API endpoints with distinct settings by enabling you to configure HttpClient objects through named clients.
• Dependency Injection Integration: It makes injecting HttpClient objects into your services simple by integrating smoothly with the ASP.NET Core dependency injection framework.

HttpClientFactory use
Let's begin by going over how to use HttpClientFactory in a.NET Core application step-by-step.
1. Set up the required NuGet package.
dotnet add package Microsoft.Extensions.Http

2. Configure HttpClient in Startup.cs
services.AddHttpClient("MyApiClient", client =>
{
    client.BaseAddress = new Uri("https://api.example.com/");
    // Additional configuration options can be set here
});

3. Inject HttpClient into your service
public class MyService
{
    private readonly HttpClient _httpClient;

    public MyService(HttpClient httpClient)
    {
        _httpClient = httpClient;
    }

    // Use _httpClient to make requests
}

4. Use IHttpClientFactory for manual creation (optional)
If you need more control, you can inject IHttpClientFactory and create HttpClient instances manually.
public class MyService
{
    private readonly IHttpClientFactory _httpClientFactory;

    public MyService(IHttpClientFactory httpClientFactory)
    {
        _httpClientFactory = httpClientFactory;
    }

    public async Task MakeRequest()
    {
        HttpClient client = _httpClientFactory.CreateClient("MyApiClient");
        HttpResponseMessage response = await client.GetAsync("/data");
        // Handle the response
    }
}

In order to effectively use HttpClient and fully utilize HttpClientFactory, one must grasp HTTP requests in.NET Core. By implementing best practices, developers may create scalable and performant apps that communicate with external APIs with ease. Examples of these practices include controlling the lifetime of HttpClient objects and utilizing dependency injection. Developers may design dependable, high-performance solutions for managing HTTP requests in their.NET Core applications with the help of HttpClient and HttpClientFactory.

Overview of the Entity Framework
A strong and adaptable Object-Relational Mapping (ORM) framework that makes database interactions in.NET applications easier is called Entity Framework (EF). We'll explore several Entity Framework techniques in this extensive tutorial, with examples to help even.NET novices understand the ideas.

Entity Framework removes the requirement for developers to write raw SQL queries by enabling them to communicate with databases using.NET objects. It supports various strategies, each having benefits and applications of its own.

1. A database-first strategy
The Database-First method entails building the database first, then using it to generate the model.
Actions

• Build Database: Using SQL Server Management Studio or another database tool, design and build the database.
• Create Model: To create the model from the current database, use the Entity Data Model Wizard.
• Employ Created Classes For database activities, make use of the automatically produced classes.

// Auto-generated class representing a table in the database
public partial class Product
{
    public int ProductID { get; set; }
    public string ProductName { get; set; }
    // Other properties
}

// Usage in code
using (var context = new YourDbContext())
{
    var products = context.Products.ToList();
    // Perform operations on products
}

2. Code-First Approach
The Code-First method starts with the creation of the domain classes, from which the database is then generated.
Actions

• Establish domain classes that represent entities by using define classes.
• Establish Relationships: To establish relationships between entities, use Data Annotations or Fluent API.
• Create Database: Based on the model, create and update the database using migrations.

public class Product
{
    public int ProductID { get; set; }
    public string ProductName { get; set; }
    // Other properties
}

public class YourDbContext : DbContext
{
    public DbSet<Product> Products { get; set; }
    // Other DbSets

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        // Fluent API configuration for relationships
    }
}

3. Model-First Method
Using the Entity Data Model Designer, the Entity Data Model (EDM) is created, and the database is subsequently generated from it via the Model-First approach.
Actions

• To develop an Entity Data Model, use the Entity Data Model Designer.
• Generate Database: Select the Generate Database from Model option to generate the database from the EDM.

As an illustration
With Entity Data Model Designer, the model-first approach frequently incorporates visual design, which makes it less code-oriented.

4. Context of Databases and LINQ Queries
Whichever strategy is used, after the model is created developers use a database context to communicate with the database via LINQ queries.

using (var context = new YourDbContext())
{
    var products = from p in context.Products
                   where p.ProductName.Contains("Shoes")
                   select p;

    // Perform operations on products
}

Comprehending the various methodologies in Entity Framework enables.NET developers to select the most appropriate technique for their project needs. Entity Framework offers flexibility and abstraction for effective database interactions in.NET applications, regardless of your preference for building databases first, writing classes, or using visual modeling.

Have fun with coding!

To start a new ASP.NET Core Web API project, use the command line or Visual Studio.
dotnet new webapi -n WorkingwithSQLLiteinAsp.NETCoreWebAPI
cd WorkingwithSQLLiteinAsp.NETCoreWebAPI

Install SQLite NuGet Package
Install the SQLite NuGet package to enable SQLite support in your project.
dotnet add package Microsoft.EntityFrameworkCore.Sqlite

Now Create SQLite Database File in your Project
SQLLiteDatabase.db

Create Model
namespace WorkingwithSQLLiteinAsp.NETCoreWebAPI.Models
{
    // Models/TodoItem.cs
    public class TodoItem
    {
        public long Id { get; set; }
        public string Name { get; set; }
        public bool IsComplete { get; set; }
    }

}

Now Crete Application Database Context
using Microsoft.EntityFrameworkCore;
using WorkingwithSQLLiteinAsp.NETCoreWebAPI.Models;

namespace WorkingwithSQLLiteinAsp.NETCoreWebAPI.ApplicationDbContext
{
    public class AppDbContext : DbContext
    {
        public AppDbContext(DbContextOptions<AppDbContext> options) : base(options) { }

        public DbSet<TodoItem> TodoItems { get; set; }
    }
}

Add Connection string in AppSetting.JSON File
// appsettings.json
{
  "ConnectionStrings": {
    "DefaultConnection": "Data Source=SQLLiteDatabase.db"
  },
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft": "Warning",
      "Microsoft.Hosting.Lifetime": "Information"
    }
  },
  "AllowedHosts": "*"
}

Register the Dependancy in Program.cs File
using Microsoft.EntityFrameworkCore;
using Microsoft.OpenApi.Models;
using WorkingwithSQLLiteinAsp.NETCoreWebAPI.ApplicationDbContext;

var builder = WebApplication.CreateBuilder(args);
var configuration = builder.Configuration;

// Add services to the container.
builder.Services.AddDbContext<AppDbContext>(options =>
        options.UseSqlite(configuration.GetConnectionString("DefaultConnection")));
builder.Services.AddControllers();
// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen(c =>
{
    c.SwaggerDoc("v1", new OpenApiInfo { Title = "Working with SQLLite In Asp.net Core Web API", Version = "v1" });

});

var app = builder.Build();

// Configure the HTTP request pipeline.
if(app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI();
}

app.UseHttpsRedirection();

app.UseAuthorization();

app.MapControllers();

app.Run();

Create and Apply Migrations
Run the following commands to create and apply migrations to create the SQLite database.
dotnet ef migrations add InitialCreate
dotnet ef database update

CRUD Operations
Implement CRUD operations in your controller.
// Controllers/TodoController.cs
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using WorkingwithSQLLiteinAsp.NETCoreWebAPI.ApplicationDbContext;
using WorkingwithSQLLiteinAsp.NETCoreWebAPI.Models;

[ApiController]
[Route("api/[controller]/[Action]")]
public class TodoController : ControllerBase
{
    private readonly AppDbContext _context;

    public TodoController(AppDbContext context)
    {
        _context = context;
    }

    // GET: api/Todo
    [HttpGet]
    public async Task<ActionResult<IEnumerable<TodoItem>>> GetTodoItems()
    {
        return await _context.TodoItems.ToListAsync();
    }

    // GET: api/Todo/5
    [HttpGet("{id}")]
    public async Task<ActionResult<TodoItem>> GetTodoItem(long id)
    {
        var todoItem = await _context.TodoItems.FindAsync(id);

        if(todoItem == null)
        {
            return NotFound();
        }

        return todoItem;
    }

    // POST: api/Todo
    [HttpPost]
    public async Task<ActionResult<TodoItem>> PostTodoItem(TodoItem todoItem)
    {
        _context.TodoItems.Add(todoItem);
        await _context.SaveChangesAsync();

        return CreatedAtAction(nameof(GetTodoItem), new { id = todoItem.Id }, todoItem);
    }

    // PUT: api/Todo/5
    [HttpPut("{id}")]
    public async Task<IActionResult> PutTodoItem(long id, TodoItem todoItem)
    {
        if(id != todoItem.Id)
        {
            return BadRequest();
        }

        _context.Entry(todoItem).State = EntityState.Modified;

        try
        {
            await _context.SaveChangesAsync();
        }
        catch(DbUpdateConcurrencyException)
        {
            if(!TodoItemExists(id))
            {
                return NotFound();
            }
            else
            {
                throw;
            }
        }

        return NoContent();
    }

    // DELETE: api/Todo/5
    [HttpDelete("{id}")]
    public async Task<IActionResult> DeleteTodoItem(long id)
    {
        var todoItem = await _context.TodoItems.FindAsync(id);
        if(todoItem == null)
        {
            return NotFound();
        }

        _context.TodoItems.Remove(todoItem);
        await _context.SaveChangesAsync();

        return NoContent();
    }

    private bool TodoItemExists(long id)
    {
        return _context.TodoItems.Any(e => e.Id == id);
    }
}

Output

Conclusion
SQLite is a relational database management system (RDBMS) that is self-contained, serverless, and requires no configuration. It is an embedded database engine that is lightweight, open-source, and runs directly on the client device, eliminating the need for a separate server process. Some of SQLite's key features are.

• Self-contained: It is simple to install and maintain because the whole database system is housed in a single library.
• Serverless: SQLite does not function as a separate server process, in contrast to conventional database management systems. Rather, it is incorporated straight into the program.
• Zero-configuration: Complex setup or administration are not necessary for SQLite. The database is a single, straightforward file that often has a.db extension; no server setup or upkeep is required.
• Cross-platform: SQLite is compatible with a number of operating systems and mobile platforms, including iOS and Android, as well as Windows, macOS, and Linux.
• Single-user: Because SQLite is optimized for single-user applications, embedded systems, mobile apps, and lightweight desktop programs can all benefit from its use.
• ACID-compliant: SQLite preserves the ACID (Atomicity, Consistency, Isolation, Durability) qualities, guaranteeing data reliability and integrity, even with its lightweight design.
• Dynamic typing: SQLite stores data using dynamic typing, which enables users to store several kinds of data in the same column.
• Broad language support: SQLite is adaptable to a variety of development contexts since it supports a wide range of programming languages, including C, C++, Java, Python, and.NET.

SQLite is often utilized in situations where a lightweight and integrated database solution is needed, such as mobile applications, desktop software, and embedded systems, because of its simplicity, portability, and ease of integration.

FluentValidation: What Is It?
An open-source validation toolkit for.NET called FluentValidation offers a fluid interface for creating and implementing validation rules. It makes validation logic easy to comprehend, write, and maintain by enabling developers to describe it succinctly and clearly.

.NET 8's FluentValidation
Installing the FluentValidation NuGet package is required in order to use FluentValidation in.NET 8. The following command can be used to accomplish this in the.NET CLI or Package Manager Console:

dotnet add package FluentValidation

Verifying a Basic User Model
Let's construct a straightforward example in which we wish to validate a User class. To make sure the user's email address is legitimate and their name is not empty, we will use FluentValidation.

using FluentValidation;

public class User
{
    public string Name { get; set; }
    public string Email { get; set; }
}

public class UserValidator : AbstractValidator<User>
{
    public UserValidator()
    {
        RuleFor(user => user.Name).NotEmpty().WithMessage("Name cannot be empty");
        RuleFor(user => user.Email).NotEmpty().EmailAddress().WithMessage("Invalid email address");
    }
}

In this instance:

• We provide properties for Name and Email in our User class definition.
• We construct a class called UserValidator, which is derived from AbstractValidator<User>.
• We define validation rules for the Name and Email properties inside the UserValidator constructor using the RuleFor method.

Applying FluentValidation to Your Software
Let's look at how we can utilize FluentValidation in our application now that we have our User class and matching validator:

class Program
{
    static void Main()
    {
        var user = new User { Name = "Mahesh Chand", Email = "[email protected]" };
        var validator = new UserValidator();

        var validationResult = validator.Validate(user);

        if (validationResult.IsValid)
        {
            Console.WriteLine("User is valid");
        }
        else
        {
            foreach (var error in validationResult.Errors)
            {
                Console.WriteLine($"Validation Error: {error.ErrorMessage}");
            }
        }
    }
}

In this instance:

• We construct an instance of the User class and set its properties.
• We instantiate a UserValidator object.
• By handing in the User instance, we invoke the Validate method on the validator.
• We verify the validity of the validation result. We print a success message if it is. If not, we repeat the mistakes and print them.

.NET 8's FluentValidation offers a tidy and expressive approach to handling validation in your applications. You can confidently design and run validation rules thanks to its fluid interface and simple syntax. Using FluentValidation makes it possible to isolate your validation logic apart from your business logic, as seen in our example, which makes your codebase easier to read and manage.

Cross-Origin Resource Sharing (CORS) is a vital security feature that controls how resources on a web page can be accessed by web applications from different domains. In an ASP.NET Core project, enabling CORS involves configuring the server to allow or restrict access to its resources from different origins. Here's a step-by-step guide on establishing CORS in your ASP.NET Core application.

Step 1. Set up the middleware for CORS

Installing the Microsoft.AspNetCore.Cors package is the first step. Using the NuGet Package Manager Console, you may accomplish this.

Install-Package Microsoft.AspNetCore.Cors

Alternatively, you can add it to your project's .csproj file:
<PackageReference Include="Microsoft.AspNetCore.Cors" Version="x.x.x" />

Replace x.x.x with the latest version available.

Step 2. Configure CORS in Startup.cs
Open your Startup.cs file and locate the ConfigureServices method. Add the CORS service by calling AddCors in the ConfigureServices method.
public void ConfigureServices(IServiceCollection services)
{
    // Other configurations

    services.AddCors(options =>
    {
        options.AddPolicy("AllowSpecificOrigin",
            builder =>
            {
                builder.WithOrigins("https://example.com")
                       .AllowAnyHeader()
                       .AllowAnyMethod();
            });
    });

    // Other configurations
}

In the code snippet above:

• The CORS services are added to the application's service container via AddCors.
• AddPolicy generates a specified CORS policy that identifies permitted origins, headers, and methods ("AllowSpecificOrigin" in this example).

To designate which domains are permitted to access your resources, modify WithOrigins. To accept requests from any origin, use a "*".

Step 3. Turn on the CORS middleware
Add the CORS middleware to Startup.cs's Configure function.

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
    // Other configurations

    app.UseCors("AllowSpecificOrigin");

    // Other configurations
}

This middleware must be added before other middleware that may handle requests, such as MVC or static file middleware.

Step 4: Verify Your CORS Setup
Once set up, make queries to your ASP.NET Core APIs from various origins to test the CORS settings. Make that the methods, headers, and permitted origins meet the needs of your application.

In summary
For secure communication between your application and clients from different domains, and to control access to your resources, you must implement CORS in your ASP.NET Core project. You can increase the security of your application while enabling critical cross-origin communication by defining CORS policies, which allow you to control which origins can access your APIs.

Always keep in mind to properly set your CORS policies based on the security requirements of your application, keeping in mind the possible hazards related to cross-origin requests.

One of the most frequent problems that developers encounter in the intricate and ever-changing process of software creation is the "class explosion." This happens when a software system has a lot of classes—often more than what was planned or organized in the first place. We will examine the reasons behind the class explosion, how it affects software systems, and management and mitigation techniques in this post.

Reasons for the Explosion of Classes
Excessively Fine-Grained Design: An excessively fine-grained design is one of the main reasons for class explosion. The number of classes can grow rapidly when every task or feature is included within a distinct class without a clear and obvious goal in mind.

class UserManager { }

Inadequate Abstraction: An excessive number of classes may result from improper abstraction. Class fragmentation occurs when developers are unable to recognize and produce meaningful abstractions, leading to an abundance of tiny, specialized classes.

class User { }
class UserValidationHelper { }
class UserPersistenceManager { }

Insufficient Planning: In some cases, inadequate upfront planning can contribute to class explosion. If the design lacks a clear structure and roadmap, developers might introduce new classes in a reactionary manner, leading to an unmanageable number of classes.

class FeatureAProcessor { }
class FeatureBProcessor { }
class FeatureCProcessor { }

The effects of the class explosion

• Complexity and Cognitive Load: The system's total complexity rises with the number of classes. The relationships and responsibilities of each class may be difficult for developers to understand, which will raise their cognitive load.
• Maintenance Challenges: Having a lot of classes may make maintenance difficult. It becomes more difficult to make modifications or add new features since developers have to work their way through a complex class hierarchy.
• Decreased Reusability: Decreased reusability may result from an excessive number of classes. It's possible that developers will have to start from scratch if they try to utilize tiny, specialized classes in other areas of the system.

Techniques to Control Class Explosion
Refactoring: Examine and reorganize the codebase on a regular basis to find and remove superfluous classes. Combine features into classes that are well-thought-out and integrated.

class UserManager { }

Abstraction and Encapsulation: Emphasize proper abstraction and encapsulation to ensure that classes have well-defined responsibilities. Avoid creating classes for every minor task and focus on creating meaningful, high-level abstractions.
    class User { }
    class UserManager { }

​​​Design Patterns: Utilize design patterns to manage class complexity. Patterns like the Singleton pattern, Factory pattern, and Strategy pattern can help organize and streamline class hierarchies.

class UserFactory { }

Modularization: Modularize the system into manageable modules or components. Divide the system into cohesive parts, each with a distinct responsibility, to prevent the proliferation of classes.
class AuthenticationModule { }

Guidelines and Code Reviews: Establish coding guidelines and conduct regular code reviews to ensure that the development team adheres to best practices. Enforce consistency in class design and encourage developers to think about the overall system architecture.

Example: Refactoring a Class Explosion
Consider a scenario where a class explosion has occurred in a system responsible for handling various geometric shapes:

class SquareValidator { }
class SquareCalculator { }
class CircleValidator { }
class CircleCalculator { }
class TriangleValidator { }
class TriangleCalculator { }

There are numerous classes as a result of this design's lack of abstraction. Let's rework this situation by adding an abstract and more unified design:

abstract class Shape { }
class Square extends Shape { }
class Circle extends Shape { }
class Triangle extends Shape { }

class ShapeValidator { }
class ShapeCalculator { }

We've added an abstract Shape class as part of this refactoring, which eliminates duplication and creates a more organized and manageable design.

In summary
Although class explosion is a typical problem in software design, it may be controlled and lessened with careful planning, frequent refactoring, and strict code standards. Developers can design systems that are not only scalable but also easier to understand and manage over time by placing a strong emphasis on appropriate abstraction, encapsulation, and modularization. Recall that a well-designed system prioritizes the classes' meaningful order and coherence over their quantity.

REST API: What is it?
REpresentational State Transfer is what the acronym REST stands for. It's an architectural design that lays forth a set of guidelines for building Web services. REST recommends generating an object from the data a client requests and responding to the user with the object's values via a client-server conversation. For instance, you can construct an object on the server-side if the user requests a Bangalore taxi reservation at a specific location and time. You have an object over here, and you are transmitting the object's state. As a result, Representational State Transfer, or REST, is its name.

An application can be made more appropriate for the internet by utilizing the reduced bandwidth usage provided by the REST architectural style. It is entirely dependent on the resources and is frequently referred to as the "language of the internet."

REST API Fundamentals
The six REST guiding principles are listed below:

Without a state

The body of the request contains the current status of the resource, and the URL is used to identify the resource specifically. The client receives a response from the server via headers, body, or status once the request has been processed. All the necessary information is included in the requests that clients send to servers so that the servers can comprehend the requests. This may appear in the body, headers, query-string arguments, or even the URL. The server API does not cache any state, thus each request is independent of the others. Additionally helpful in scaling the API service in a cloud context is its RESTful characteristic.

Client-Server
The client-server architecture enables a uniform interface and separates clients from the servers. This enhances the portability across multiple platforms as well as the scalability of the server components.

Uniform Interface
To obtain the uniformity throughout the application, REST has the following four interface constraints:

• Resource identification
• Resource Manipulation using representations
• Self-descriptive messages
• Hypermedia as the engine of application state

Cacheable
To provide a better performance, the applications are often made cacheable. This is done by labeling the response from the server as cacheable or non-cacheable either implicitly or explicitly. If the response is denied as cacheable, then the client cache can reuse the response data for equivalent responses in the future.
Minimal APIs in .Net 8 or .Net 7

Minimal APIs are architected to create HTTP APIs with minimal dependencies. They are ideal for microservices and apps that want to include only the minimum files, features, and dependencies in ASP.NET Core.

Limitations of Minimal API

• No support for filters: For example, no support for IAsyncAuthorizationFilter, IAsyncActionFilter, IAsyncExceptionFilter, IAsyncResultFilter, and IAsyncResourceFilter.
• No support for model binding, i.e. IModelBinderProvider, IModelBinder. Support can be added with a custom binding shim.
• No support for binding from forms. This includes binding IFormFile. We plan to add support for IFormFile in the future.
• No built-in support for validation, i.e. IModelValidator
• No support for application parts or the application model. There's no way to apply or build your own conventions.
• No built-in view rendering support. We recommend using Razor Pages for rendering views.
• No support for JsonPatch
• No support for OData
• No support for ApiVersioning. See this issue for more details.

With the following APIs,

REST APIs follow standard HTTP Verbs like GET, POST, PUT, DELETE, PATCH which are basically CRUD operation on an object. The APIs are arranged to form an internet resource. For example in the above example, we have resource as “todoitem” which can be created, modified, deleted using APIs, and URL format is formed accordingly.

using Microsoft.EntityFrameworkCore;
var builder = WebApplication.CreateBuilder(args);
// Add services to the container.
// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();
builder.Services.AddDbContext < TodoDb > (opt => opt.UseInMemoryDatabase("TodoList"));
var app = builder.Build();
// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment()) {
    app.UseSwagger();
    app.UseSwaggerUI();
}
app.MapGet("/", () => "Hello World!");
app.MapGet("/todoitems", async (TodoDb db) => await db.Todos.ToListAsync());
app.MapGet("/todoitems/complete", async (TodoDb db) => await db.Todos.Where(t => t.IsComplete).ToListAsync());
app.MapGet("/todoitems/{id}", async (int id, TodoDb db) => await db.Todos.FindAsync(id)
    is Todo todo ? Results.Ok(todo) : Results.NotFound());
app.MapPost("/todoitems", async (Todo todo, TodoDb db) => {
    db.Todos.Add(todo);
    await db.SaveChangesAsync();
    return Results.Created($ "/todoitems/{todo.Id}", todo);
});
app.MapPut("/todoitems/{id}", async (int id, Todo inputTodo, TodoDb db) => {
    var todo = await db.Todos.FindAsync(id);
    if (todo is null) return Results.NotFound();
    todo.Name = inputTodo.Name;
    todo.IsComplete = inputTodo.IsComplete;
    await db.SaveChangesAsync();
    return Results.NoContent();
});
app.MapDelete("/todoitems/{id}", async (int id, TodoDb db) => {
    if (await db.Todos.FindAsync(id) is Todo todo) {
        db.Todos.Remove(todo);
        await db.SaveChangesAsync();
        return Results.Ok(todo);
    }
    return Results.NotFound();
});
app.Run();
class Todo {
    public int Id {
        get;
        set;
    }
    public string ? Name {
        get;
        set;
    }
    public bool IsComplete {
        get;
        set;
    }
}
class TodoDb: DbContext {
    public TodoDb(DbContextOptions < TodoDb > options): base(options) {}
    public DbSet < Todo > Todos => Set < Todo > ();
}

In summary
The REST architecture style offers a common method for clients to access and retrieve server data as well as a standard approach to arrange resources across the internet. Minimal APIs need to have the least amount of code possible and can be quickly and simply created without the need for authentication or with very little dependencies by sitting behind a gateway that does.