CODEWITHSUNDEEP
javascriptangularreduxngrx
Itai
Itai

Reputation: 417

NGRX: The right way to create a "global" action that multiple reducer react upon?

What is to correct way to declare an "INIT_ACTION" that all reducers in the ActionReducerMap can react upon?

this an example of how my code, I need all 3 reducers (images, tags, addedTags) to react to a single action :

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

import * as fromRoot from '../../../store';

import * as fromImages from './image.reducer';
import * as fromTags from './tag.reducer';
import * as fromAddedTags from './added-tag.reducer';

export interface AnalysisState {
    images: fromImages.State;
    tags: fromTags.State;
    addedTags: fromTags.State;
}
export interface State extends fromRoot.State {
    analysis: AnalysisState;
}

export const reducers: ActionReducerMap<AnalysisState> = {
    images: fromImages.reducer,
    tags: fromTags.reducer,
    addedTags: fromAddedTags.reducer
};

export const getAnlysisState = createFeatureSelector<AnalysisState>('analysis');

this is an example actions file:

import { Action } from '@ngrx/store';
import { Tag } from '../../models/tag.model';

export const enum AddedTagActionTypes {
    ADD_TAG = '[ANALYSIS] - Add Tag'
}

export class AddTag implements Action {
    readonly type = AddedTagActionTypes.ADD_TAG;
    constructor(public payload: Tag) {}
}

export type AddedTagActions = AddTag;

and this is an example reducer:

import { EntityState, EntityAdapter, createEntityAdapter } from '@ngrx/entity';

import * as fromAddedTag from '../actions/added-tag.actions';
import { Tag } from '../../models/tag.model';

export interface State extends EntityState<Tag> {}
export const adapter: EntityAdapter<Tag> = createEntityAdapter<Tag>({
    selectId: tag => tag.id
});

export const initialState: State = adapter.getInitialState({});
export function reducer(state = initialState, action: fromAddedTag.AddedTagActions): State {
    switch (action.type) {
        case fromAddedTag.AddedTagActionTypes.ADD_TAG: {
            return adapter.addOne(action.payload, state);
        }

        default: {
            return state;
        }
    }
}
const { selectIds, selectEntities, selectAll, selectTotal } = adapter.getSelectors();


export const getAllAddedTags = selectAll;

Upvotes: 5

Views: 915

Answers (1)

danday74
danday74

Reputation: 57046

An action passes through all reducers. Therefore, if you simply put a case statement for that action in all 3 reducers then it will hit all 3 case statements.

If there is no case statement for a specific action in a reducer then the default case statement will be triggered which simply returns the original state, leaving it unmodified.

This assumes that you are not lazy loading reducers. A reducer will of course only be triggered if it is loaded.

Upvotes: 4

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