Join Justin Schwartzenberger for an in-depth discussion in this video Injection token, part of Angular 2 Essential Training.
- [Instructor] So the inject decorator with it's…string literal works but there's a better…way to do this.…Relying on string literals for tokens…is always a bit of a risk.…They are harder to maintain, easier…to mistype, and code editors don't have…much opportunity to keep track…of them to aid in refactoring.…Angular has a solution for this.…It's called an injection token.…You can use an injection token…to tell Angular you want to have…a concrete type that can be passed around.…
Let's refactor the lookup list value type…to use an injection token.…First, let's create a new file…called providers.ts in the app folder.…And let's move the lookup list value…instantiation from the app.module.ts file…into this new file.…Now the provider metadata property…in the app module is going to need this…lookup list variable.…
So, let's add the export keyword…in front of the const statement…so that we can import it into the…app.module.ts file.…To create an injection token we need…to import the class type.…It's part of the Angular coroscope package…
Justin Schwartzenberger steps through the framework one feature at a time, focusing on the new component-based architecture of Angular 2. You'll learn what Angular is and what it can do, as Justin builds a full-featured web app from start to finish. After mastering the essentials, you can tackle the other project-based courses in our library and create your own Angular app.
- What is Angular?
- Setting up an Angular template
- Creating a component
- Binding events and properties
- Getting data to components
- Using directives and pipes
- Creating Angular forms
- Validating form data
- Understanding dependency injection
- Providing services
- Making HTTP calls
Skill Level Intermediate
Q: This course was updated on 03/01/2018. What changed?
A: The following topics were updated: directives and pipes, forms, dependency injection and services, HTTP, and routing.
1. Architecture Overview
3. Directives and Pipes
5. Dependency Injection and Services
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