Injectiontoken

Angular's dependency injection Injectiontoken system manages dependencies in a modular, scalable manner.

Zahra Namini. March 15, in. Injection tokens are a popular way of providing dependencies in Angular. They are used to provide a value, such as a service instance or a configuration setting, to a component or other part of the application. Below is a simple example of setting up an injection token and using it.

Injectiontoken

As you might have already understood the Angular dependency injection layer keeps a map of providers that are being identified by "keys", also known as "injection tokens", and uses this map to resolve, create and inject instances at runtime. The injection tokens can be of different types. We have already tried Types and Strings in action in previous sections. Type-based injection tokens are the most commonly used way to register providers. Typically you import the service type from the corresponding file and put it into the providers section of the module. Another way to register a provider involves the string-based injection tokens. Typically you are going to use strings when there is no Type reference available, for example when registering plain values or objects:. That enables static type checks and prevents many type-related errors at early stages. Let's create separate file tokens. Now we can use this token within the main application module to register a URL value that all components and services can use when needed:. From this moment we can use the same token to import registered value in the service or a component like in the example below:. That does not affect the process of dependency injection but gives you an opportunity for static compile-time checks and auto completion if your code editor supports TypeScript. Let's create a token for the LoggerConfig interface we set up in this chapter earlier:.

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Today, I'm thrilled to dive into the fascinating world of InjectionTokens in Angular. If you're not already familiar with them, InjectionTokens are superheroes in the Angular universe, allowing us to leverage the full potential of dependency injection with a hint of TypeScript magic. In this blog post, we'll explore how these powerful tokens will be used to handle small values and tackle complex data structures, unlocking a plethora of possibilities for your app. In Angular, dependency injection is the backbone of building scalable and maintainable applications. It enables us to provide the necessary dependencies to our components and services without hardcoding them, promoting flexibility and testability. Enter InjectionTokens, an elegant way to inject dependencies that don't fit the traditional mold of classes or interfaces. These tokens are unique markers used to identify and retrieve specific instances from the Angular injector. Next, we must provide the theme configuration using the InjectionToken in the app's module or a feature module. Now, we can inject the theme configuration using the InjectionToken in our components and services. In this example, the ThemeComponent uses the injected themeConfig object to dynamically apply the primary and secondary colors to the background and text.

Injectiontoken

At first, I would like to thank Omer Incirkus , who helped me write this article and was with me while I was learning, for his contributions. Dependency injection is a crucial concept in Angular that enables you to create loosely coupled components, services, and modules. With dependency injection, you can declare a service or component once and reuse it throughout your application, which makes your code more modular, testable, and maintainable. Angular provides different ways to inject dependencies into your components, such as constructor injection. However, sometimes you may want to inject a value that is not a class or a service instance but rather a simple configuration value, such as a string, number, or boolean.

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Publishing to NPM One essential concept in Angular's dependency injection system is Injection Tokens. Before diving into Injection Tokens, let's briefly understand the concept of dependency injection in Angular. Creating Modules 4. Unlike regular class dependencies, which are resolved by the type, Injection Tokens offer more flexibility and control over dependency resolution. Pipes with Parameters 9. Automating with Travis Loading Server-Side Configuration File Prerequisites 1. See Also 3. Creating a Simple Component 5. Switching Languages Getting Started 3.

As you might have already understood the Angular dependency injection layer keeps a map of providers that are being identified by "keys", also known as "injection tokens", and uses this map to resolve, create and inject instances at runtime.

Rather than hard-coding these settings within the service, we can create an Injection Token and use it to provide the configuration values. Sign up to receive useful software development tips and news from the Don't Panic Labs team. Output Events 5. Built-in Pipes 9. Angular CLI 4. Injecting Multiple Instances 6. Component Lifecycle 5. Input Properties 5. Let's create separate file tokens. Providers 5. Modules 3. Dependency injection is a design pattern that allows us to provide dependent objects to a class rather than having the class create them itself. Below is a simple example of setting up an injection token and using it.