Microsoft.Extensions .DependencyInjection .NET 9 (Working With PDF)

Dependency Injection Container

1. Service Registration: Dependencies are registered in a DI container, typically at the application's composition root. These registrations specify how the container should create and manage the dependencies.

2. Dependency Resolution: When a component requests a dependency, the DI container resolves the dependency by creating an instance of a registered type that uses an extension method.

Types of Dependency Injection

• Constructor Injection: Registered services are provided to a class through its constructor, which is the most common and recommended form of DI.
• Method Injection: Services are resolved and passed as parameters to a method.
• Property Injection: Singleton services or services with a scoped lifetime can be assigned to class properties. However, this approach is less common and often considered inferior to constructor injection because it can introduce hidden dependencies.

Understanding Lifetimes in Dependency Injection (DI): Scoped, Transient, and Singleton

1. Scoped: Scoped dependencies are created once per request or lifetime scope, meaning the container provides the same instance within a single request or operation. This consistency is particularly useful in web applications, where scoped dependencies help maintain a stable dependency throughout a web request.
2. Transient: Transient dependencies are instantiated each time they are requested from the container. This implies that a new instance of a transient dependency is generated whenever it is needed. Typically, transient dependencies are used for lightweight, stateless services or components.
3. Singleton: Singleton dependencies are instantiated only once and shared throughout the application's entire lifetime. This ensures that the same instance of a singleton dependency is used for all requests throughout the application's duration. Singleton dependencies are typically employed for stateful services or components that need to be universally accessible across the entire application.

Installing Microsoft.Extensions.DependencyInjection package

Install-Package Microsoft.Extensions.DependencyInjection

Example: Basic Dependency Injection

In this example, let's create a sample app (console application) wherein we'll utilize a service provider to resolve services and inject them into our program.

using Microsoft.Extensions.DependencyInjection;
using System;

// Define a service interface
public interface IMessageService
{
    void SendMessage(string message);
}

// Implement the service interface
public class ConsoleMessageService : IMessageService
{
    public void SendMessage(string message)
    {
        Console.WriteLine(message); // Output the message to the console
    }
}

using Microsoft.Extensions.DependencyInjection;
using System;

// Define a service interface
public interface IMessageService
{
    void SendMessage(string message);
}

// Implement the service interface
public class ConsoleMessageService : IMessageService
{
    public void SendMessage(string message)
    {
        Console.WriteLine(message); // Output the message to the console
    }
}

The code snippet creates an interface IMessageService for sending messages, like a contract for how messages should be sent. The ConsoleMessageService class implements this interface by using Console.WriteLine to send messages. This separation allows the concept of sending messages to be changed independently of how they are sent, making the system flexible and manageable.

class Program
{
    static void Main(string[] args)
    {
        // Create a service provider
        var serviceProvider = new ServiceCollection()
            // Register the service implementation
            .AddTransient<IMessageService, ConsoleMessageService>()
            .BuildServiceProvider();

        // Resolve the service
        var messageService = serviceProvider.GetRequiredService<IMessageService>();

        // Use the service to send a message
        messageService.SendMessage("Hello, From Dependency Injection!");
    }
}

class Program
{
    static void Main(string[] args)
    {
        // Create a service provider
        var serviceProvider = new ServiceCollection()
            // Register the service implementation
            .AddTransient<IMessageService, ConsoleMessageService>()
            .BuildServiceProvider();

        // Resolve the service
        var messageService = serviceProvider.GetRequiredService<IMessageService>();

        // Use the service to send a message
        messageService.SendMessage("Hello, From Dependency Injection!");
    }
}

This code sets up a serviceProvider to manage services. It registers ConsoleMessageService as the implementation for IMessageService, making it available to be injected wherever required. The Main method then retrieves an instance of IMessageService from the serviceProvider and uses it to send a message to the console.

Output: The program prints the string message "Hello, From Dependency Injection!"

IronPDF: C# PDF Library

IronPDF is a powerful library for C# that simplifies the complex process of PDF generation, offering a wide range of features for PDF manipulation, including the ability to generate PDFs from HTML, operate adding text to PDFs and editing PDFs with images, creating secure documents, and much more.

public interface IPdfService
{
    void GeneratePdf(string baseUrl, string query, string filePath);
}

public interface IPdfService
{
    void GeneratePdf(string baseUrl, string query, string filePath);
}

using IronPdf;
using System;
using System.Web;

// Implement the PDF generation interface
public class IronPdfService : IPdfService
{
    public void GeneratePdf(string baseUrl, string query, string filePath)
    {
        License.LicenseKey = "Your-License-Key"; // Set the IronPDF license key
        string encodedQuery = HttpUtility.UrlEncode(query); // Encode the query string
        string fullUrl = $"{baseUrl}?query={encodedQuery}"; // Construct the full URL
        var renderer = new ChromePdfRenderer(); // Create a PDF renderer
        var pdf = renderer.RenderUrlAsPdf(fullUrl); // Render the PDF from the URL
        pdf.SaveAs(filePath); // Save the PDF to the specified file path
        Console.WriteLine($"PDF successfully created from: {fullUrl}");
        Console.WriteLine($"Saved to: {filePath}");
    }
}

using IronPdf;
using System;
using System.Web;

// Implement the PDF generation interface
public class IronPdfService : IPdfService
{
    public void GeneratePdf(string baseUrl, string query, string filePath)
    {
        License.LicenseKey = "Your-License-Key"; // Set the IronPDF license key
        string encodedQuery = HttpUtility.UrlEncode(query); // Encode the query string
        string fullUrl = $"{baseUrl}?query={encodedQuery}"; // Construct the full URL
        var renderer = new ChromePdfRenderer(); // Create a PDF renderer
        var pdf = renderer.RenderUrlAsPdf(fullUrl); // Render the PDF from the URL
        pdf.SaveAs(filePath); // Save the PDF to the specified file path
        Console.WriteLine($"PDF successfully created from: {fullUrl}");
        Console.WriteLine($"Saved to: {filePath}");
    }
}

builder.Services.AddSingleton<IPdfService, IronPdfService>();

builder.Services.AddSingleton<IPdfService, IronPdfService>();

public class MyController : Controller
{
    private readonly IPdfService _pdfService;

    public MyController(IPdfService pdfService)
    {
        _pdfService = pdfService;
    }

    public IActionResult GeneratePdf()
    {
        string baseUrl = "https://ironpdf.com/";
        string query = "Hello World from IronPDF !";
        string filePath = "Demo.pdf";

        // Use the injected PDF service to generate a PDF
        _pdfService.GeneratePdf(baseUrl, query, filePath);

        return View();
    }
}

public class MyController : Controller
{
    private readonly IPdfService _pdfService;

    public MyController(IPdfService pdfService)
    {
        _pdfService = pdfService;
    }

    public IActionResult GeneratePdf()
    {
        string baseUrl = "https://ironpdf.com/";
        string query = "Hello World from IronPDF !";
        string filePath = "Demo.pdf";

        // Use the injected PDF service to generate a PDF
        _pdfService.GeneratePdf(baseUrl, query, filePath);

        return View();
    }
}

Conclusion

Microsoft.Extensions.DependencyInjection is a powerful tool in .NET 6 for implementing dependency injection, which promotes loose coupling and enhances testability in applications. By integrating IronPDF, a feature-rich C# library, developers can easily generate comprehensive PDF documents with minimal effort. Licensing for IronPDF is available.