Angular Redux Pattern in Angular

The Angular Redux pattern is used to manage application state in large-scale Angular applications. This pattern is based on the Redux architecture which uses a single, immutable data store for application state. This helps to simplify complex state management and makes it easier to maintain.

Syntax

The Redux pattern involves creating actions, reducers, and selectors.

Actions

export enum ActionType {
  ADD_TODO = '[Todo] Add',
  REMOVE_TODO = '[Todo] Remove',
  UPDATE_TODO = '[Todo] Update'
}

export class AddTodo implements Action {
  readonly type = ActionType.ADD_TODO;
  constructor(public payload: Todo) {}
}

export class RemoveTodo implements Action {
  readonly type = ActionType.REMOVE_TODO;
  constructor(public payload: string) {}
}

export class UpdateTodo implements Action {
  readonly type = ActionType.UPDATE_TODO;
  constructor(public payload: Todo) {}
}

export type TodoActions = AddTodo | RemoveTodo | UpdateTodo;

Reducers

export const initialState: Todo[] = [];

export function todoReducer(state = initialState, action: TodoActions) {
  switch (action.type) {
    case ActionType.ADD_TODO:
      return [...state, action.payload];

    case ActionType.REMOVE_TODO:
      return state.filter(todo => todo.id !== action.payload);

    case ActionType.UPDATE_TODO:
      return state.map(todo => todo.id === action.payload.id ? action.payload : todo);

    default:
      return state;
  }
}

Selectors

export const selectTodos = (state: AppState) => state.todos;

export const selectTodoById = (id: string) => createSelector(
  selectTodos,
  todos => todos.find(todo => todo.id === id)
);

Example

A Todo app can be implemented using the Redux pattern in Angular. Here's an example of how it can be implemented:

@Component({
  selector: 'app-todo',
  template: `
    <div *ngFor="let todo of todos$ | async">
      <input [(ngModel)]="todo.description" />
      <button (click)="remove(todo.id)">Remove</button>
    </div>

    <input [(ngModel)]="newTodo" />
    <button (click)="add()">Add</button>
  `
})
export class TodoComponent {
  todos$: Observable<Todo[]>;
  newTodo = '';

  constructor(private store: Store<AppState>) {
    this.todos$ = this.store.pipe(select(selectTodos));
  }

  add() {
    const todo: Todo = { id: uuid(), description: this.newTodo };
    this.store.dispatch(new AddTodo(todo));
    this.newTodo = '';
  }

  remove(id: string) {
    this.store.dispatch(new RemoveTodo(id));
  }
}

Output

The above example will produce a TODO app that displays a list of todos and allows users to add and remove todos.

Explanation

The Redux pattern uses a single data store to manage application state, making it easier to manage complex state in large-scale applications. The store can only be updated through actions, ensuring that state mutations are predictable and testable. Reducers are used to update the store based on incoming actions, and selectors are used to extract data from the store in a predictable manner.

Use

The Angular Redux pattern is best suited for large-scale applications that require complex state management. It can be used to manage any type of application state, including user authentication, form state, and data persistence. The pattern is easy to scale and can be used in conjunction with other Angular state management libraries like ngrx.

Important Points

• Use actions, reducers, and selectors to manage application state in Angular
• The Redux pattern is best suited for large-scale Angular applications that require complex state management
• Use immutability to ensure predictable state mutations
• Use selectors to extract data from the store in a predictable manner

Summary

The Angular Redux pattern is an effective way to manage complex application state in large-scale Angular applications. It involves creating actions, reducers, and selectors to manage state in an immutable and predictable manner. The Redux pattern is best suited for managing complex application state, and it can be used in conjunction with other Angular state management libraries to scale applications effectively.