Mastering State Management in Angular Applications
The Challenge of Data Persistence
When building a large-scale Angular application, managing state can be a daunting task. Unlike backend applications, which rely on databases for state management, frontend applications require a mechanism to handle data effectively. This data can range from server responses to form input data and user routes. To overcome this challenge, it’s essential to compose all application state in a central store for easy management and data communication.
Introducing NgRx: A Solution for State Management
NgRx is a collection of libraries for reactive extensions and state management in Angular applications. It simplifies the application’s state by enforcing unidirectional data flow and modeling the state in objects. A complete state management system should enable you to model a state, update its value, monitor the state when the value changes, and retrieve the values of the state.
Understanding NgRx Store
The NgRx Store is a Redux-inspired state management system that enables you to use observables to manage state in an Angular application. The primary advantage of using the NgRx Store is the ability to store all state in a single tree that is accessible from any part of the application.
How NgRx Works
NgRx uses the Redux pattern, which consists of three main concepts:
- Store: A central store that holds all of the application state
- Action: Describes all the changes in the state of the application
- Reducers: Tie the store and actions together by using the defined action to carry out a state transition, depending on the action
Building a Simple Angular App using NgRx Store
To demonstrate the power of NgRx, let’s build a simple Angular app that uses the NgRx Store to manage state. We’ll start by setting up a new Angular application and installing the NgRx Store. Then, we’ll create a store directory inside our src/app directory, where we’ll define our models, actions, and reducers.
Defining Models, Actions, and Reducers
We’ll define a courseItem.model.ts file to hold our interface for the course list. Next, we’ll create an Actions directory and define a course.action.ts file, where we’ll import the NgRx Action and create an AddItemAction that implements the NgRx Action.
Creating the Reducer
We’ll create a reducers directory and define a course.reducer.ts file, where we’ll import the courseItem model, CourseAction action, and CourseActionType action. We’ll create an initial state that uses the CourseItem interface for validation and define a reducer function that takes a state and an action as a parameter.
Registering NgRx in the App Module
We’ll register NgRx in our root app.modules.ts file by importing CourseReducer and registering it in the imports array. We’ll also import the Angular FormsModule, which we’ll be using shortly.
Using NgRx in Components
We’ll modify our root app.component.ts file to use NgRx. We’ll bring in RxJS Observables, our defined courseItem interface, and our app state. We’ll set courseItems$ to a type of observable, which will be a type of array.
Adding a Course
We’ll create a simple form for users to add a new course. We’ll use Bootstrap for a nice-looking user interface and add the Bootstrap CSS CDN to our app/index.html. We’ll modify our app.component.html file to create a basic form for adding the course name and department.
Dispatching the AddItemAction
We’ll import NgForm in our TypeScript file and create a method to dispatch the AddItemAction. We can now add a new course using the form we created.
Conclusion
Working with large-scale applications requires good architecture and organized structure. State management tools such as NgRx can help you maintain a readable codebase as your app scales. By understanding the basic concepts behind state management, you’ll be able to use tools such as Redux and Vuex in your projects more effectively.