We can utilize Dapper, an ORM (Object-Relational Mapper) or, more accurately, a Micro ORM, to interface with the database in our projects. Dapper allows us to write SQL statements just like we would in a SQL Server. Dapper works well since it doesn't convert.NET queries into SQL.

Dapper's SQL Injection safety is crucial to know since it allows us to perform parameterized queries, which is something we should do at all times. The fact that Dapper supports a variety of database providers is another crucial factor. In order to query our database, it offers helpful extension methods that extend ADO.NET's IDbConnection. Writing queries that work with our database provider is a must, of course.

Company.cs
using System.ComponentModel.DataAnnotations;

namespace DapperApp.Model
{
    public class Company
    {
        public int Id { get; set; }

        [Display(Name = "Company Name")]
        [Required(ErrorMessage = "Company Name is required")]
        public string CompanyName { get; set; }

        [Display(Name = "Company Address")]
        [Required(ErrorMessage = "Company Address is required")]
        public string CompanyAddress { get; set; }

        [Required(ErrorMessage = "Country is required")]
        public string Country { get; set; }

        [Display(Name = "Glassdoor Rating")]
        [Range(1, 5, ErrorMessage = "Glassdoor Rating must be between 1 and 5")]
        public int GlassdoorRating { get; set; }
    }
}

HomeController.cs
using Dapper;
using DapperApp.Model;
using DapperApp.Repository;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using System.Data;

namespace DapperApp.ControllerApp
{
    public class HomeController : Controller
    {
        readonly IGenericRepository _genericController;

        public HomeController(IGenericRepository genericController)
        {
            _genericController = genericController;
        }
        // GET: HomeController
        public async Task<IActionResult> Index()
        {
            var query = "SELECT * FROM Companies";

            var companies = await _genericController.GetData<Company>(query);
            return View(companies);
        }

        // GET: HomeController/Details/5
        public async Task<IActionResult> Details(int id)
        {
            var query = "SELECT * FROM Companies WHERE Id = @Id";
            if (id == null)
            {
                return NotFound();
            }

            var company = await _genericController.GetDataById<Company>(query, id);
            if (company == null)
            {
                return NotFound();
            }

            return View(company);
        }

        // GET: HomeController/Create
        public ActionResult Create()
        {
            return View();
        }

        // POST: HomeController/Create
        [HttpPost]
        [ValidateAntiForgeryToken]
        public async Task<IActionResult> Create([Bind("Id,CompanyName,CompanyAddress,Country,GlassdoorRating")] Company company)
        {
            var parameters = new DynamicParameters();
            parameters.Add("CompanyName", company.CompanyName, DbType.String);
            parameters.Add("CompanyAddress", company.CompanyAddress, DbType.String);
            parameters.Add("Country", company.Country, DbType.String);
            parameters.Add("GlassdoorRating", company.GlassdoorRating, DbType.Int32);
            var query = "INSERT INTO Companies (CompanyName, CompanyAddress, Country,GlassdoorRating) VALUES (@CompanyName, @CompanyAddress, @Country, @GlassdoorRating)";

            if (ModelState.IsValid)
            {
                await _genericController.CreateData(query, parameters);
                return RedirectToAction("Index");
            }
            return View(company);
        }


        // GET: HomeController/Edit/5
        public ActionResult Edit(int id)
        {
            return View();
        }

        // POST: HomeController/Edit/5
        [HttpPost]
        [ValidateAntiForgeryToken]
        public async Task<IActionResult> Edit(int id, [Bind("Id,CompanyName,CompanyAddress,Country,GlassdoorRating")] Company company)
        {
            if (id != company.Id)
            {
                return NotFound();
            }
            var parameters = new DynamicParameters();
            parameters.Add("CompanyName", company.CompanyName, DbType.String);
            parameters.Add("CompanyAddress", company.CompanyAddress, DbType.String);
            parameters.Add("Country", company.Country, DbType.String);
            parameters.Add("GlassdoorRating", company.GlassdoorRating, DbType.Int32);
            parameters.Add("Id", company.Id, DbType.Int32);
            var query = "UPDATE Companies SET CompanyName = @CompanyName, CompanyAddress = @CompanyAddress, Country = @Country, GlassdoorRating = @GlassdoorRating WHERE Id = @Id";

            if (ModelState.IsValid)
            {
                await _genericController.UpdateData(query, parameters);
                return RedirectToAction("Index");
            }

            return View(company);
        }

        // GET: HomeController/Delete/5
        public ActionResult Delete(int id)
        {
            return View();
        }

        // POST: HomeController/Delete/5
        [HttpPost]
        [ValidateAntiForgeryToken]
        public async Task<IActionResult> DeleteConfirmed(int id)
        {
            var query = "DELETE FROM Companies WHERE Id = @Id";
            await _genericController.DeleteData(query, id);
            return RedirectToAction("Index");
        }
    }
}

DapperContext.cs

using System.Data;
using Microsoft.Data.SqlClient;

namespace DapperApp.Context
{
    public class DapperContext
    {
        private readonly IConfiguration _configuration;
        private readonly string _connectionString;
        public DapperContext(IConfiguration configuration)
        {
            _configuration = configuration;
            _connectionString = _configuration.GetConnectionString("DefaultConnection");
        }

        public IDbConnection CreateConnection() => new SqlConnection(_connectionString);
    }
}

IGenericRepository.cs

using DapperApp.Model;

namespace DapperApp.Repository
{
    public interface IGenericRepository
    {
        Task CreateData(string query, DynamicParameters parameters);
        Task DeleteData(string query, int id);
        Task<T> GetDataById<T>(string query, int id);
        Task<IEnumerable<T>> GetData<T>(string SQL, string DbName = "TEST");
        Task UpdateData(string query, DynamicParameters parameters);
    }
}

C#

GenericRepository.cs

using DapperApp.Context;
using DapperApp.Model;
using DapperApp.Repository;
using Dapper;
using Microsoft.Data.SqlClient;
using System.Data;

namespace DapperApp.Repository
{
    public class GenericRepository: IGenericRepository
    {
        readonly DapperContext _context;

        public GenericRepository(DapperContext context)
        {
            this._context = context;
        }

        public async Task<IEnumerable<T>> GetData<T>(string SQL, string DbName = "TEST")
        {

            using (var connection = _context.CreateConnection())
            {
                var companies = await connection.QueryAsync<T>(SQL);
                return companies.ToList();
            }
        }
        public async Task<T> GetDataById<T>(string query, int id)
        {
            using (var connection = _context.CreateConnection())
            {
                var company = await connection.QuerySingleOrDefaultAsync<T>(query, new { id });
                return company;
            }
        }

        public async Task CreateData(string query, DynamicParameters parameters)
        {

            using (var connection = _context.CreateConnection())
            {
                await connection.ExecuteAsync(query, parameters);
            }
        }

        public async Task UpdateData(string query, DynamicParameters parameters)
        {

            using (var connection = _context.CreateConnection())
            {
                await connection.ExecuteAsync(query, parameters);
            }
        }


        public async Task DeleteData(string query, int id)
        {
            using (var connection = _context.CreateConnection())
            {
                await connection.ExecuteAsync(query, new { id });
            }
        }

    }
}

Overview
Greetings, fellow programmers! Has your.NET project ever left you entangled in the complex web of dependency injection? Do not be alarmed! We've got you covered, and today we're launching the revolutionary SuperInject NuGet Library!

How does SuperInject work?
SuperInject is your reliable dependency injection sidekick, not just another NuGet package. Imagine this: simplified service and repository registration that incorporates a little bit of fun and simplicity.

How to Begin
First Step: The Installation Dance
Now let's start the celebration! Grab a terminal and give SuperInject a hug:

dotnet add package SuperInject

SuperInject loves to be invited to the party!

Step 2. Mark Your Classes, It’s Attribute Time!
Now, here comes the fun part. Mark your classes with the ServiceAttribute or RepositoryAttribute. It’s like giving your classes a VIP pass for the dependency injection club.

using SuperInject;

[Service(ServiceLifetime.Singleton)]
public class MySingletonService : ISomeInterface
{
// Implementation goes here...
}

And for repositories:
using SuperInject;

[Repository(ServiceLifetime.Transient)]
public class MyTransientRepository : ISomeInterface
{
// Implementation goes here...
}

Let’s Get SuperInjecting!

The stage is set, and the lights are on, now let’s call the shots with the SuperInject extension method. In your Startup.cs or Program.cs file, give your services and repositories a grand entrance:
// ConfigureServices method in Startup.cs
public void ConfigureServices(IServiceCollection services)
{
// Use the AddSuperInject extension method to automatically register services and repositories
services.AddSuperInject();

// Your other service registrations go here...

// And the party continues...
}

Why SuperInject?
Attribute Awesomeness: No more tedious configurations! SuperInject’s attributes make your classes stand out, like stars on the red carpet.
Extension Method Magic: Say goodbye to manual registrations. Let SuperInject handle the heavy lifting, leaving you with more time for the fun stuff.
Avoid Circular Dependency Drama: SuperInject knows how to navigate the tricky paths of circular dependencies. It’s like having a GPS for your dependency injection journey.

Wrapping Up
SuperInject isn’t just a NuGet package; it’s your accomplice in writing cleaner, more maintainable code. So, what are you waiting for? Add a dash of SuperInject to your projects, and let the dependency injection party begin!

Ready to supercharge your dependency injection game? Grab SuperInject, and let the coding festivities begin!

A more complete and reliable substitute for the built-in DateTime and DateTimeOffset classes in the.NET Framework is the date and time management library NodaTime. It is intended to handle typical problems and intricacies related to changing dates and times.

Important aspects of NodaTime

• Immutable Types: NodaTime represents dates, times, and durations using immutable types. This encourages the development of a more consistent and thread-safe programming model and aids in the prevention of accidental object change.
• Rich number of Types: NodaTime offers a rich number of types, such as ZonedDateTime (a date and time in a particular time zone), LocalDate (a date without a time), Instant (a point on the timeline), and LocalTime (a time without a date).
• Time Zones: NodaTime provides extensive time zone support, enabling developers to operate across time zones, carry out conversions, and manage changes in daylight saving time.
• Duration and Period: To handle time spans and calendar discrepancies, respectively, more expressively and precisely, NodaTime provides the Duration and Period types.
• Compatibility with.NET Platforms: NodaTime is made to function with the.NET Framework,.NET Core, and.NET 5/6, among other.NET platforms.
• Improved Thread Safety: Reasoning about concurrent programs requiring date and time operations is made easier by the usage of immutable types.
• NodaTime's extensibility enables developers to specify their own calendar systems and, if necessary, provide more time zone data.
• Testing Support: NodaTime comes with features to make testing easier, like a FakeClock to manage time in unit tests.

The programming approach known as "code-behind" allows for a more tidy division of responsibilities by separating the HTML code and display logic. It entails putting the code in a different class file, which can make it easier to comprehend and manage.

Most people associate Microsoft web forms with Code-Behind. Please be aware that the CodeBehind framework has nothing to do with Microsoft's previous web form; rather, it is a back-end framework for.NET Core. With the Code-Behind pattern, the server-side and client-side developers carry out the development work independently of each other, fully separating the design (such as HTML) from the server-side coding portion.

The issue of conditionals and loops
Please be aware that unless the server part code is added, variables such as those between the design part code are still regarded as Code-Behind.

It is quite obvious when variables are included between html or xml codes, etc.

Variable examples between the design section
Razor syntax

<h1>@model.PageName</h1>

Standard syntax
<h1><%=model.PageName%></h1>

The @model in the previous two cases.The Code-Behind method is still in place because PageName and <%=model.PageName%> data are clearly visible in the html tags and are easily recognizable by designers or client-side developers.

This is built on the Code-Behind design, thus there won't be any issues.

However, in most cases, you should either add the server side codes in the design part or the server side codes in the design part for recurring sections like loops and conditions.

Therefore, there is no way out!

In the design part is an illustration of server-side coding.
<table>
    <thead>
        <tr>
            <th>Column1</th>
            <th>Column2</th>
            <th>Column3</th>
        </tr>
    </thead>
    <tbody>
        @foreach (var item in Model)
        {
            <tr>
                <td>@item.Column1</td>
                <td>@item.Column2</td>
                <td>@item.Column3</td>
            </tr>
        }
    </tbody>
</table>

Example of integration of the design part in the server-side codes

model.ListValue = "<ul>";

foreach(string s in List)
    model.ListValue += "<li>" + s + "</li>";

model.ListValue += "</ul>";

Using Code-Behind Compliance Templates
Microsoft's web form was one of the most well-known frameworks that ensured the separation of server-side scripts from the design department. However, this guarantee came at a high cost, with extra codes and limited designer control over the design department.

The most recent version of the CodeBehind framework includes a new recursion template feature that allows for the development of a 100% Code-Behind based design structure.

A page view's templates are segments that are linked to template variables prior to the compilation of the view section.

Both standard and razor syntax use the template. It is not possible to utilize the standard syntax template for razor syntax or the razor syntax template for standard syntax.
A basic template example using standard syntax.
<%@ Page Controller="YourProjectName.DefaultController" Model="YourProjectName.DefaultModel" %>
<!DOCTYPE html>
<html>
<head>
+   <#GlobalTags#>
    <title><%=model.PageTitle%></title>
</head>
<body>
    <%=model.BodyValue%>
</body>
</html>

+<#GlobalTags
+<meta charset="utf-8" />
+<meta name="viewport" content="width=device-width, initial-scale=1.0" />
+<meta http-equiv="Content-Type" content="text/html; charset=utf-16" />
+<meta http-equiv="content-language" content="en">
+<script type="text/javascript" src="/client/script/global.js" ></script>
+<link rel="alternate" type="application/rss+xml" title="rss feed" href="/rss/" />
+<link rel="shortcut icon" href="/favicon.ico" />
+<link rel="stylesheet" type="text/css" href="/client/style/global.css" />
+#>

The output is translated as follows in this example when the Template variable calls a Template section.
<%@ Page Controller="YourProjectName.DefaultController" Model="YourProjectName.DefaultModel" %>
<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta http-equiv="Content-Type" content="text/html; charset=utf-16" />
    <meta http-equiv="content-language" content="en">
    <script type="text/javascript" src="/client/script/global.js" ></script>
    <link rel="alternate" type="application/rss+xml" title="rss feed" href="/rss/" />
    <link rel="shortcut icon" href="/favicon.ico" />
    <link rel="stylesheet" type="text/css" href="/client/style/global.css" />
    <title><%=model.PageTitle%></title>
</head>
<body>
    <%=model.BodyValue%>
</body>
</html>

The aforementioned example introduced you to the idea of templates and demonstrated their basic functionality in the CodeBehind framework. However, return templates have one special feature: they are first put into the template before replacing the entire template.

Two categories of templates exist.

Template: Return to template
The template variable can be used to call either type of template.
A template definition example using Razor syntax.

+@#TemplateName{
@{
string ExampleText = "This is example text";
}
<b>Example value is : @ExampleText</b>
+}

In each template definition, the at sign and sharp (@#) characters are used first, followed by the template name, and finally the block character ({) at the conclusion. The block is closed (}) when the desired values have been added.The template variable must be written in order to call the template. The name of the template is typed after the sign and sharp (@#) letters are added at the beginning to write the template variable.Example of using a template variable to call a template.

<!DOCTYPE html>
<html>
<body>
+  @#TemplateName
</body>
</html>

Example of after pasting the template.

<!DOCTYPE html>
<html>
<body>
@{
string ExampleText = "This is example text";
}
<b>Example value is : @ExampleText</b>
</body>
</html>

Returned templates are first inserted into a variable with the same name as the template name, and then the entire template is replaced by the returned template (all three are the same name).

The at sign and sharp (@#) characters are used at the beginning of each return template definition, and then the name of the template is written. Then, the equal character (=) is added, and at the end, the block character ({) is used. Then, the desired values are added, and finally, the block is closed (}).

Example (Razor syntax)View the section before pasting the template.

In the codes above, there is a return template called Tags, which is specified with the string @#Tags= and its value is known inside the blockpPasting template auto step 1.

<div class="header">
  <a href="#default">@model.Title</a>
  <div class="header-right">
    @#Tags={<a href="@#Href">@#PageName</a>}
  </div>
</div>

@#Tags{
@foreach (PageItem page in model.PageItemList)
{
    <a href="@#Href">@#PageName</a>
}
}

@#PageName{@page.Title}
@#Href{@(((page.Path == "main")? "/" : page.Path))}

As you can see in the above codes. First, the value inside the returned template block with the name Tags is replaced in the Tags template variable inside the Tags template.

pasting template auto step 2.
<div class="header">
  <a href="#default">@model.Title</a>
  <div class="header-right">
    @foreach (PageItem page in model.PageItemList)
    {
        <a href="@#Href">@#PageName</a>
    }
  </div>
</div>

@#PageName{@page.Title}
@#Href{@(((page.Path == "main")? "/" : page.Path))}

According to the above codes, in the second step, the values of the Tags template are replaced in the place of the returned template.

pasting template auto step 3 (finally).

<div class="header">
  <a href="#default">@model.Title</a>
  <div class="header-right">
    @foreach (PageItem page in model.PageItemList)
    {
        <a href="@(((page.Path == "main")? "/" : page.Path))">@page.Title</a>
    }
  </div>
</div>

In the last step, the values of other templates are replaced in the place of template variables.

In the template placement example, if you add the template externally, you will have the following html in the design section.

View the section before pasting the template.

<div class="header">
  <a href="#default">@model.Title</a>
  <div class="header-right">
+    @#Tags={<a href="@#Href">@#PageName</a>}
  </div>
</div>

Without a return template, at best, you will have the following html in the design section.

View the section without the use of the return template.

<div class="header">
  <a href="#default">@model.Title</a>
  <div class="header-right">
+ @foreach (PageItem page in model.PageItemList)
+ {
+    <a href="@(((page.Path == "main")? "/" : page.Path))">@page.Title</a>
+ }
  </div>
</div>

Please note that this was a simple example, and the situation may be very complex.

You can also use a template for standard syntax. The following code shows the previous template example in standard syntax.

<div class="header">
  <a href="#default"><%=model.Title%></a>
  <div class="header-right">
    <#Tags=<a href="<#Href#>"><#PageName#></a>#>
  </div>
</div>

<#Tags
<% foreach (PageItem page in model.PageItemList)
{
    <#Tags#>
}
%>
#>

<#PageName <%=page.Title%>#>
<#Href <%=((page.Path == "main")? "/" : page.Path)%>#>

If the return value is placed between the standard syntax tags, the syntax will be automatically closed before the return value, and the syntax will be opened after it.
Copy template auto step finally for standard syntax.

<div class="header">
  <a href="#default"><%=model.Title%></a>
  <div class="header-right">
    <% foreach (PageItem page in model.PageItemList)
    {
        %><a href="<%=((page.Path == "main")? "/" : page.Path)%>"><%=page.Title%></a><%
    }
    %>
  </div>
</div>

Conclusion
No matter how much you try to avoid mixing server-side codes in the view section, in some cases, such as loops and conditions, you will have to use server-side codes in the view section; the presence of mixing server-side codes reduces the readability of the codes and makes the appearance of the view section ugly, and it becomes difficult to maintain the codes and also leads to complex interaction between the server-side and client-side developers in high-scale applications. Applying the return template keeps the code of the server section outside the view section. As a result, the view section will have a great appearance, and the Code-Behind pattern will be fully respected.

DateTime Fundamentals in C#
Before we go into formatting, let's go over the fundamentals of working with DateTime in C#. The DateTime structure represents dates and times and provides methods for modifying and comparing dates. DateTime can be used to get the current date and time.DateTime can now be used to denote a specific date.DateTime or Parse.ParseExact.

DateTime Object Formatting
When it comes to turning DateTime objects into human-readable strings, the ToString method is the major player. To produce the desired output, you can use standard format specifiers or custom format strings.
Specifiers of Standard Format

You can use the ToString function with a set of standard format specifiers provided by C#.

C# provides a set of standard format specifiers that you can use with the ToString method.

    "d": Short date pattern
    "t": Short time pattern
    "f": Full date/time pattern (short time)
    "g": General date/time pattern (short time)
    "s": Sortable date/time pattern (ISO 8601)
    "u": Universal sortable date/time pattern (UTC)

DateTime now = DateTime.Now; string shortDate = now.ToString("d"); string fullDateTime = now.ToString("f");

Custom Format Strings
For more control over the formatting, you can use custom format strings.
    "yyyy": Four-digit year
    "MM": Two-digit month
    "dd": Two-digit day
    "HH": Two-digit hour (24-hour clock)
    "mm": Two-digit minute
    "ss": Two-digit second

DateTime now = DateTime.Now; string customFormat = now.ToString("yyyy-MM-dd HH:mm:ss");

Handling Time Zones
Dealing with time zones is a common challenge in programming. You can use the DateTime methods ToUniversalTime and ToLocalTime to convert between UTC and local time.
DateTime utcNow = DateTime.UtcNow; DateTime localTime = utcNow.ToLocalTime();

Example 1. Using Standard Format Specifiers
using System;

class Program
{
    static void Main()
    {
        DateTime now = DateTime.Now;

        // Short date pattern
        string shortDate = now.ToString("d");
        Console.WriteLine("Short Date: " + shortDate);

        // Full date/time pattern (short time)
        string fullDateTime = now.ToString("f");
        Console.WriteLine("Full Date/Time: " + fullDateTime);

        // Sortable date/time pattern (ISO 8601)
        string sortableDateTime = now.ToString("s");
        Console.WriteLine("Sortable Date/Time: " + sortableDateTime);
    }
}

Output
Short Date: 11/25/2023 Full Date/Time: Sunday, November 25, 2023 3:23 PM Sortable Date/Time: 2023-11-25T15:23:45
Example 2. Using Custom Format Strings
using System;

class Program
{
    static void Main()
    {
        DateTime now = DateTime.Now;

        // Custom format: yyyy-MM-dd HH:mm:ss
        string customFormat = now.ToString("yyyy-MM-dd HH:mm:ss");
        Console.WriteLine("Custom Format: " + customFormat);

        // Custom format: ddd, MMM dd yyyy
        string customFormat2 = now.ToString("ddd, MMM dd yyyy");
        Console.WriteLine("Custom Format 2: " + customFormat2);
    }
}

Output

Custom Format: 2023-11-25 15:23:45
Custom Format 2: Sun, Nov 25 2023

Experiment with various format strings and tailor them to your specific needs and tastes. Customizing the format enables you to display dates and times in the manner that is most appropriate for your application or user interface.

Conclusion
Date and time formatting in C# is an essential skill for any developer. Understanding the subtleties of DateTime formatting is critical whether you're presenting dates in a user interface, logging events, or dealing with time-sensitive data. Experiment with alternative format specifiers, develop custom formats, and take time zone differences into account to guarantee your apps handle dates and times correctly and logically. You're well-equipped to tackle the problems of managing temporal data in C# with these skills in your toolbox. Have fun coding!

Maintaining consistency across numerous processes can be difficult in the world of distributed systems and microservices architecture. The Saga pattern saves the day by managing a series of distributed transactions to ensure data consistency without relying on a two-phase commit process. In this post, we'll look at how to implement the Saga pattern with Rebus, a versatile.NET messaging package, and RabbitMQ, a sophisticated message broker.

What exactly is the Saga Pattern?
The Saga pattern, at its core, maintains a chain of local transactions, with each step representing a transaction involving distinct services or components. If any step fails, compensating actions are taken to ensure overall consistency.

Sagas ensure that either all operations within the sequence succeed or, in the case of failure, the system reverts to a consistent state by executing compensating actions.
Using Rebus and RabbitMQ

Setting Up Rebus and RabbitMQ

To begin, install the necessary packages using NuGet.
Install-Package Rebus
Install-Package Rebus.RabbitMQ

Next, configure Rebus and RabbitMQ:
var configurer = Configure.With(...)
    .Transport(t => t.UseRabbitMq("amqp://localhost", "saga-example"))
    .Start();

Implementing a Saga
Let's consider a hypothetical e-commerce scenario where a customer places an order consisting of multiple steps: reserve items, charge payment, and ship items. We'll implement a saga to manage these operations.
public class OrderSagaData
{
    public Guid OrderId { get; set; }
    public bool ItemsReserved { get; set; }
    public bool PaymentCharged { get; set; }
    public bool ItemsShipped { get; set; }
}

public class OrderSaga : Saga<OrderSagaData>,
    IAmInitiatedBy<PlaceOrder>,
    IHandleMessages<ReserveItems>,
    IHandleMessages<ChargePayment>,
    IHandleMessages<ShipItems>
{
    // Saga implementation here
}

Handling Messages in the Saga
Each message represents a step in the saga. For instance, the PlaceOrder message initiates the saga.
public class PlaceOrder
{
    public Guid OrderId { get; set; }
    public List<Item> Items { get; set; }
}

public async Task Handle(PlaceOrder message)
{
    Data.OrderId = message.OrderId;
    // Reserve items logic
    Bus.Send(new ReserveItems { OrderId = message.OrderId, Items = message. Items });
}

Similarly, other messages like ReserveItems, ChargePayment, and ShipItems are handled within the saga, managing the respective operations and updating saga data accordingly.

Compensating Actions
Should any step fail, compensating actions ensure the system maintains consistency. For instance, if charging payment fails, a compensating action might be implemented as follows.
public async Task Handle(ChargePayment message)
{
    // Charge payment logic
    if (paymentFailed)
    {
        // Execute compensating action
        Bus.Send(new CancelOrder { OrderId = Data.OrderId });
    }
}

Implementing the Saga pattern using Rebus and RabbitMQ offers a powerful way to manage distributed transactions and maintain data consistency in a microservices architecture. By orchestrating a sequence of steps and incorporating compensating actions, sagas ensure system integrity despite failures within the distributed environment.

The Visitor Pattern is used in an ASP.NET Core Web API with a 3-tier design for efficient data manipulation in the C# Article model. The model, CSharpArticle, contains critical features. A Data Access Layer with a repository manages database interactions, a Business Layer with the Visitor interface and Article Service, and a Presentation Layer with the API controllers comprise the architecture. In the Business Layer, the Visitor Pattern is used to conduct operations on articles, allowing for clean separation of responsibilities and enabling reusable, structured, and scalable code. This architecture ensures that CRUD activities benefit from the flexibility of the Visitor Pattern while preserving a clear division of responsibilities across the application layers.

Overview of Three-Tier Architecture
The Presentation Layer manages the API controllers and interacts with the client.
The business logic, data validation, and any special business rules are all contained in the business layer.
Data Access Layer: Manages data retrieval and storage, as well as database interaction.

Article Model in C#
Let's start with the Article model.
public class CSharpArticle
{
    public int Id { get; set; }
    public string Title { get; set; }
    public string Content { get; set; }
}

Data Access Layer
Repository Interface:
public interface IArticleRepository
{
    CSharpArticle GetArticleById(int id);
    void AddArticle(CSharpArticle article);
    void UpdateArticle(CSharpArticle article);
    void DeleteArticle(int id);
}

Repository Implementation:
public class ArticleRepository: IArticleRepository
{
    private readonly CSharpCornerArticleProject _context;

    public ArticleRepository(YourDbContext context)
    {
        _context = context;
    }

    public CSharpArticle GetArticleById(int id)
    {
        return _context.Articles.FirstOrDefault(a => a.Id == id);
    }

    public void AddArticle(CSharpArticle article)
    {
        _context.Articles.Add(article);
        _context.SaveChanges();
    }

    public void UpdateArticle(CSharpArticle article)
    {
        _context.Articles.Update(article);
        _context.SaveChanges();
    }

    public void DeleteArticle(int id)
    {
        var article = _context.Articles.FirstOrDefault(a => a.Id == id);
        if (article != null)
        {
            _context.Articles.Remove(article);
            _context.SaveChanges();
        }
    }

    public void Accept(IArticleVisitor visitor, int articleId)
    {
        var article = GetArticleById(articleId);
        visitor.Visit(article);
        UpdateArticle(article);
    }
}

Business Layer
Visitor Interface
public interface IArticleVisitor
{
    void Visit(CSharpArticle article);
}

public class ContentAnalyzerVisitor: IArticleVisitor
{
    public void Visit(CSharpArticle article)
    {
        if (article != null)
        {
            int wordCount = CountWords(article.Content);
            bool hasKeywords = CheckForKeywords(article.Content);

            article.WordCount = wordCount;
            article.HasKeywords = hasKeywords;
        }
    }

    private int CountWords(string content)
    {
        if (string.IsNullOrWhiteSpace(content))
            return 0;

        string[] words = content.Split(new char[] { ' ', '.', ',', ';', '!', '?' }, StringSplitOptions.RemoveEmptyEntries);
        return words.Length;
    }

    private bool CheckForKeywords(string content)
    {
        string[] keywordsToCheck = { "C#", "ASP.NET", "Entity Framework" }; if needed
        foreach (string keyword in keywordsToCheck)
        {
            if (content.Contains(keyword, StringComparison.OrdinalIgnoreCase))
            {
                return true;
            }
        }
        return false;
    }
}

Article Service:
public class ArticleService
{
    private readonly IArticleRepository _repository;

    public ArticleService(IArticleRepository repository)
    {
        _repository = repository;
    }

    public void Accept(IArticleVisitor visitor, int articleId)
    {
        CSharpArticle article = _repository.GetArticleById(articleId);
        visitor.Visit(article);
        _repository.UpdateArticle(article);
    }

    public void Publish(int articleId)
    {
        CSharpArticle article = _repository.GetArticleById(articleId);
        article.Publish();
        _repository.UpdateArticle(article);
    }

    public void Archive(int articleId)
    {
        CSharpArticle article = _repository.GetArticleById(articleId);
        article.Archive();
        _repository.UpdateArticle(article);
    }
}

Presentation Layer (Controller)
Controller:
[Route("api/articles")]
[ApiController]
public class CSharpArticleController : ControllerBase
{
    private readonly ArticleService _articleService;

    public CSharpArticleController(ArticleService articleService)
    {
        _articleService = articleService;
    }

    [HttpGet("{id}")]
    public IActionResult Get(int id)
    {
        var article = _articleService.GetArticle(id);
        if (article == null)
        {
            return NotFound();
        }
        return Ok(article);
    }

    [HttpPost]
    public IActionResult Post([FromBody] CSharpArticle article)
    {
        if (article == null)
        {
            return BadRequest();
        }
        _articleService.CreateArticle(article);
        return CreatedAtAction("Get", new { id = article.Id }, article);
    }

    [HttpPut("{id}")]
    public IActionResult Put(int id, [FromBody] CSharpArticle article)
    {
        if (id != article.Id)
        {
            return BadRequest();
        }
        _articleService.UpdateArticle(article);
        return NoContent();
    }

    [HttpDelete("{id}")]
    public IActionResult Delete(int id)
    {
        var existingArticle = _articleService.GetArticle(id);
        if (existingArticle == null)
        {
            return NotFound();
        }
        _articleService.DeleteArticle(id);
        return NoContent();
    }
}

Conclusion
This structure separates concerns and enables the Visitor Pattern to conduct actions on the Article model across levels, maintaining logical separation and reusability. The repository, service, and controller implementations may alter depending on the database, ORM, or particular requirements of your application. While the Visitor Pattern can be useful in some situations, it may not be required for every CRUD action. Always evaluate the pattern's true need in the context of your application's complexity and requirements.

The implementation of the Visitor Pattern for C# Article management in an ASP.NET Core Web API following a 3-tier design provides a strong structure for managing CRUD activities. The CSharpArticle model is at the heart of data operations, which are governed by the Data Access Layer via the ArticleRepository. This repository communicates with the database and supports CRUD operations. The Business Layer, represented by the ArticleService, orchestrates operations on articles by utilizing the Visitor Pattern to perform specified tasks via visitors such as content analysis, publishing, archiving, and other appropriate actions.The Presentation Layer's CSharpArticleController serves as the interface for external interactions. It interfaces with the ArticleService to handle HTTP requests, allowing it to get, create, update, and delete articles. Each method correlates to an HTTP verb, allowing for smooth communication with the underlying layers and, ultimately, efficient and controlled article administration.

This hierarchical architecture enables code that is modular, scalable, and maintainable. It allows the program to handle additional features or changes without interfering with core functionality. The application of the Visitor Pattern within the three-tier architecture increases the system's flexibility by fostering a clear separation of responsibilities and improving the API's overall performance and maintainability.

Database access is an important component of application development, and optimizing it is key for overall speed and user experience. C# is a flexible language used for building robust applications in the.NET ecosystem. Using actual examples, we'll look at numerous ways for improving database access in.NET.

1. Select the Best Data Access Technology
Let's start by looking at several data access mechanisms in.NET and offering examples of how to use them effectively.
Example: ADO.NET
using System;
using System.Data.SqlClient;

class Program
{
    static void Main()
    {
        string connectionString = "YourConnectionString";

        using (SqlConnection connection = new SqlConnection(connectionString))
        {
            connection.Open();

            // Perform database operations using SqlCommand, SqlDataReader, etc.

            connection.Close();
        }
    }
}

Example: Entity Framework
using System;
using System.Linq;

class Program
{
    static void Main()
    {
        using (var context = new YourDbContext())
        {
            // Use LINQ queries to interact with the database
            var result = context.YourEntity.Where(e => e.SomeProperty == "SomeValue").ToList();
        }
    }
}

Example: Dapper
using System;
using System.Data;
using System.Data.SqlClient;
using Dapper;

class Program
{
    static void Main()
    {
        string connectionString = "YourConnectionString";

        using (IDbConnection dbConnection = new SqlConnection(connectionString))
        {
            // Use Dapper for simplified data access
            var result = dbConnection.Query("SELECT * FROM YourTable WHERE SomeProperty = @SomeValue", new { SomeValue = "SomeValue" });
        }
    }
}

2. Optimize Database Queries
Efficiently constructing queries is crucial for optimal database performance. Let's look at examples of query optimization.
Example: Parameterized Queries
using System;
using System.Data.SqlClient;

class Program
{
    static void Main()
    {
        string connectionString = "YourConnectionString";

        using (SqlConnection connection = new SqlConnection(connectionString))
        {
            connection.Open();

            string parameterizedQuery = "SELECT * FROM YourTable WHERE SomeColumn = @SomeValue";

            using (SqlCommand command = new SqlCommand(parameterizedQuery, connection))
            {
                command.Parameters.AddWithValue("@SomeValue", "SomeValue");

                // Execute the command
            }

            connection.Close();
        }
    }
}

Example: Avoid SELECT *
using System;
using System.Data.SqlClient;

class Program
{
    static void Main()
    {
        string connectionString = "YourConnectionString";

        using (SqlConnection connection = new SqlConnection(connectionString))
        {
            connection.Open();

            // Instead of selecting all columns, specify only the required ones
            string query = "SELECT Column1, Column2 FROM YourTable";

            using (SqlCommand command = new SqlCommand(query, connection))
            {
                // Execute the command
            }

            connection.Close();
        }
    }
}

3. Connection Management
Efficient connection management is vital for optimizing database access. Let's see examples of good connection practices.
Example: Connection Pooling
Connection pooling is automatically handled by ADO.NET, so there's usually no explicit code needed. Ensure that you close connections promptly to allow them to return to the pool.

Example: Async Database Operations
using System;
using System.Data.SqlClient;
using System.Threading.Tasks;

class Program
{
    static async Task Main()
    {
        string connectionString = "YourConnectionString";

        using (SqlConnection connection = new SqlConnection(connectionString))
        {
            await connection.OpenAsync();

            // Perform asynchronous database operations

            connection.Close();
        }
    }
}

4. Caching
Implementing caching mechanisms can significantly reduce the need for repeated database queries. Let's look at examples of result caching.
Example: Result Caching
using System;
using System.Collections.Generic;
using System.Runtime.Caching; // Use MemoryCache for simplicity

class Program
{
    static void Main()
    {
        // Check if data is in cache
        var cachedData = MemoryCache.Default.Get("YourCachedDataKey") as List;

        if (cachedData == null)
        {
            // Data not in cache, retrieve from the database
            // ...

            // Cache the data
            MemoryCache.Default.Add("YourCachedDataKey", dataFromDatabase, DateTimeOffset.UtcNow.AddMinutes(10));
        }
        else
        {
            // Use the cached data
        }
    }
}

5. Monitoring and Profiling
Monitoring and profiling database interactions help identify bottlenecks. Let's see examples of logging.
Example: Logging
using System;
using System.Diagnostics;
using System.Data.SqlClient;

class Program
{
    static void Main()
    {
        string connectionString = "YourConnectionString";

        using (SqlConnection connection = new SqlConnection(connectionString))
        {
            connection.Open();

            // Log the start time
            Stopwatch stopwatch = Stopwatch.StartNew();

            // Perform database operations using SqlCommand, SqlDataReader, etc.

            // Log the end time
            stopwatch.Stop();
            Console.WriteLine($"Query executed in {stopwatch.ElapsedMilliseconds} milliseconds");

            connection.Close();
        }
    }
}

Optimizing database access in .NET involves choosing the right data access technology, optimizing queries, managing connections efficiently, implementing caching, and monitoring performance. By applying these examples and best practices, you can ensure that your .NET applications have a responsive and performant database layer, contributing to an overall smoother user experience.

Assume you run an online store and, every month, you send a marketing email to consumers who have registered on your site highlighting the latest products from your store in order to increase sales. Your CEO, on the other hand, wants to know how many customers actually open these emails. If you can't pay third-party email tracking solutions, you can utilize the following way to see if your emails have been opened. Create an API first. If our customers open our emails, this API will record the messages they send back.

[ApiController]
[Route("api/[controller]")]
public class EmailTrackingController : Controller
{
    [HttpGet("EmailOpener")]
    public ActionResult EmailOpener(string email, string eventId)
    {
        //Your logic here to capture email & eventId
        //maybe save email and eventID to DB

        byte[] pixel = Convert.FromBase64String("R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7");
        return new FileContentResult(pixel, "image/gif");
    }
}

As you can see, I've built an EmailTracking controller with a GET method called EmailOpener that takes two parameters: email and eventId.

When a customer opens your marketing email, this API is invoked, and their email address, along with the eventId, is provided to it. The email and eventId can then be captured and saved in your database. You might have noticed that I returned the encoded value "R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7."

This isn't just any dummy value; it's a legitimate base64-encoded representation of a tiny transparent GIF image. Assume the short HTML text below is your marketing email for the forthcoming Black Friday Sales.

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Black Friday Sales</title>
</head>
<body>
    <h1>Hi, check out our Black Friday Sales!!!</h1>

    <img alt="" src="https://www.mysite.com/EmailTracking/EmailOpener?email=ENCODED_EMAIL_ADDRESS&eventId=BlackFridaySales2023" width="1" height="1" style="border: none; display: block;" />

    <!-- Main content images -->
    <img src="https://www.mysite.com/contents/image/BFD2023.PNG" alt="Black Friday Deals" />

    <!-- Dummy messages -->
    <p>Dummy Message....</p>
    <p>Dummy Message....</p>
    <p>Dummy Message....</p>
</body>
</html>

As you can see in the email, I have included the following html snippet
<img alt="" src="@Email&eventId=BlackFridaySales2023">https://www.mysite.com/EmailTracking/EmailOpener?email=@Email&eventId=BlackFridaySales2023" width="1" height="1" style="border-width: 0px; border-style: solid;" />

This is an HTML image tag with a 1x1 pixel size that contains a link to our EmailOpener API. Because of its small size, the buyer will overlook it when they read our marketing email. As you can see, I used @Email for the email field; this is a variable that will be substituted with the email address of the real recipient.

When a customer reads your email, the 1x1 pixel picture loads and the URL (in this case, "https://www.mysite.com/EmailTracking/EmailOpener?email=@Email&eventId=BlackFridaySales2023") is triggered. This enables us to determine who opened the email and for what event.

Redirect Image Clickable
Some email providers, however, automatically prevent photos from loading and only display the images if the user chooses to view or download them. If this occurs, our 1x1 pixel image will not work because our consumers will not see it in the email, let alone download it.

To avoid this problem, we can include an appealing image in the email along with a call-to-action such as 'Click the image to discover more amazing deals!' We can redirect them to our API and store their email address in our database whenever they click the image.

To help with this, I've included a new API method called RedirectCustomer.
public ActionResult RedirectCustomer(string email, string eventId)
{
    //Your logic here to capture email & eventId
    //maybe save email and eventID to DB

    if (eventId == "BlackFridaySales2023")
    {
        return Redirect("https://www.mysite.com/BFD2023LandingPage");
    }
    else {
    return Redirect("https://www.mysite.com");
    }
}

This function will record the customer's incoming email and route them to the relevant page based on the incoming eventID. If we notice an incoming client with the eventID 'BlackFridaySales2023,' for example, we'll redirect them to our Black Friday Promotions landing page.

Include the following html image element in the email you send to the customer.
<a href="https://www.mysite.com/EmailTracking/RedirectCustomer?email=@email&eventId=BlackFridaySales2023">
     <img alt="Black Friday Promotion 2023" class="fullWidth" src="https://www.mysite.com/Content/images/BFD2023.png" style="display: block; height: auto; border: 0px; max-width: 600px; width: 100%;" title="Black Friday Promotion 2023!" width="600" />
</a>

An image entitled 'BFD2023.png' will be prominently shown in the email sent to our consumers. When the customer clicks on this image, they will be taken to our API at https://www.mysite.com/EmailTracking/RedirectCustomer?email=@Email&eventId=BlackFridaySales2023. At this point, the customer's email address will be saved in our database. This information allows us to track the email open rate, which can then be examined after the offer is over to determine the campaign's reach and effectiveness.

Some Things to Think About
If you intend to service a large number of customers, you must address potential concerns such as database locks, concurrency, and server overload. It is critical to guarantee that your infrastructure can manage a high amount of incoming requests. Furthermore, further coding steps are required to manage concurrency and prevent database locking from a programming standpoint.

ASP.NET Core is a versatile and robust web application framework. Middleware is one of its core characteristics, and it plays a critical role in processing requests and responses as they travel through your application. This post will explain what middleware is, how it works, and why it is necessary for developing powerful online applications in ASP.NET Core.

ASP.NET Core Middleware

In ASP.NET Core, middleware is a collection of components that are added to the application's request processing pipeline. Each middleware component is responsible for processing an incoming request or an outgoing answer. Middleware components can be added, removed, or reordered, allowing developers to tailor the request-handling pipeline to the specific demands of their application.

Middleware can handle a wide range of responsibilities, including authentication, routing, caching, logging, and more. It functions similarly to a chain of building blocks, with each block performing a specified operation on the request or response before passing it on to the next middleware in the pipeline.

The Middleware Anatomy
In ASP.NET Core, middleware components are often implemented as classes with a specified signature. They accept an HTTP context containing information about the incoming request and allow them to modify the answer. This is the fundamental structure of middleware.

public class MyMiddleware
{
    private readonly RequestDelegate _next;

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

    public async Task InvokeAsync(HttpContext context)
    {
        // Do something before the next middleware
        // ...

        await _next(context); // Call the next middleware in the pipeline

        // Do something after the next middleware
        // ...
    }
}

In this case, RequestDelegate represents the next middleware in the pipeline, and the InvokeAsync method provides the logic that will run before and after the next middleware.

In Use Middleware
Consider the following example, in which we wish to track the path of each incoming request.

public class LoggingMiddleware
{
    private readonly RequestDelegate _next;

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

    public async Task InvokeAsync(HttpContext context)
    {
        // Log the request path
        Console.WriteLine($"Request to: {context.Request.Path}");

        await _next(context); // Call the next middleware in the pipeline
    }
}

We can add this middleware to the pipeline in the Startup.cs file.
public void Configure(IApplicationBuilder app)
{
    app.UseMiddleware<LoggingMiddleware>();

    // Other middleware and configuration...
}

Now, every incoming request's path will be logged before it proceeds through the pipeline.

Ordering Middleware
The order in which middleware components are added to the pipeline matters. Middleware is executed in the order it's added, from top to bottom. For example, if you want to perform authentication before routing, you should add authentication middleware before routing middleware.

public void Configure(IApplicationBuilder app)
{
    app.UseAuthentication(); // Add authentication middleware
    app.UseRouting(); // Add routing middleware

    // Other middleware and configuration...
}

Middleware is a fundamental concept in ASP.NET Core, allowing you to modularize and customize request and response processing in your web applications. By understanding how middleware works and how to leverage it effectively, you can build robust and flexible web applications that meet your specific requirements. Whether you're handling authentication, logging, or any other aspect of request processing, middleware is a powerful tool in your ASP.NET Core toolbox.