@ngrx/store

State Management

This code demonstrates how to set up a basic state management system using @ngrx/store. The StoreModule is imported and configured with a reducer.

import { StoreModule } from '@ngrx/store';
import { counterReducer } from './counter.reducer';

@NgModule({
  imports: [
    StoreModule.forRoot({ count: counterReducer })
  ]
})
export class AppModule {}

Actions

This code shows how to create actions using the createAction function. Actions are dispatched to trigger state changes.

import { createAction } from '@ngrx/store';

export const increment = createAction('[Counter] Increment');
export const decrement = createAction('[Counter] Decrement');
export const reset = createAction('[Counter] Reset');

Reducers

This code defines a reducer function using createReducer and on functions. The reducer handles different actions to update the state.

import { createReducer, on } from '@ngrx/store';
import { increment, decrement, reset } from './counter.actions';

export const initialState = 0;

const _counterReducer = createReducer(initialState,
  on(increment, state => state + 1),
  on(decrement, state => state - 1),
  on(reset, state => initialState)
);

export function counterReducer(state, action) {
  return _counterReducer(state, action);
}

Selectors

This code demonstrates how to create selectors to read specific pieces of state. Selectors are used to derive data from the store.

import { createSelector, createFeatureSelector } from '@ngrx/store';

export const selectCounterState = createFeatureSelector<number>('count');

export const selectCount = createSelector(
  selectCounterState,
  (state: number) => state
);