Accessing HttpClient in Blazor WASM: A Guide to Dependency Injection in C#

Learn how to access `HttpClient` and other services in a plain C# class within a Blazor WebAssembly project using Dependency Injection.
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Accessing HttpClient in Blazor WASM: A Guide to Dependency Injection in C#

Blazor WebAssembly (WASM) is a powerful framework that allows developers to build interactive web applications using C# . One of the core features of Blazor is its ability to leverage Dependency Injection (DI). This can sometimes be confusing, especially when trying to access services like HttpClient in plain C# files outside of Razor components.

In this guide, we'll clarify how you can access injected objects in plain C# code as opposed to a Razor page. We will break down the steps necessary to achieve this and provide insights into how the DI system works in a Blazor application.

Understanding Dependency Injection

Before diving into the solution, it's crucial to understand the fundamentals of Dependency Injection in Blazor.

What is Dependency Injection?

Dependency Injection is a design pattern that allows a class to receive its dependencies from an external source rather than creating them internally. This promotes loose coupling and enhances testability.

How Does It Work in Blazor?

In Blazor, when you register services in the service container, those services can be injected into your components and other classes. The framework takes care of instantiating these dependencies and injecting them where needed.

Accessing HttpClient in C# Classes

Let’s explore the steps required to access HttpClient from a plain C# class, for example, a class called DbIo:

Step 1: Register HttpClient in the Service Container

First, you need to ensure that HttpClient is correctly registered in your Program.cs file:

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This line of code registers HttpClient as a scoped service, which means it will have a lifespan equal to the HTTP request.

Step 2: Create Your Custom Service Class

Next, create a custom service class where you will utilize HttpClient. Here's an example of what your DbIo class might look like:

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Step 3: Register Your Custom Service

You must now register DbIo for it to be injectable in your Blazor components.

[[See Video to Reveal this Text or Code Snippet]]

Step 4: Inject Your Custom Service in a Blazor Component

In any Blazor component (e.g., App.razor), inject the DbIo service like so:

[[See Video to Reveal this Text or Code Snippet]]

This line forces the instantiation of a DbIo instance and ensures that HttpClient is passed to it via its constructor.

Conclusion

Accessing HttpClient in a plain C# class within a Blazor WASM project is straightforward once you understand the structure and dependencies involved. The key steps include registering services in the DI container, creating custom service classes that accept those services via constructor parameters, and injecting those custom services into Blazor components.

By following these steps, you can effectively manage dependencies and maintain clean and testable code in your Blazor applications. Happy coding!

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