How to add state properties from component

问题

I'm currently working on a project that involves state management for individual components using Angular 7 and NGRX. However, I need to make this implementation scalable, meaning it can be used multiple times while still working independent.

So far I have managed to get my state running and sorted out all action in my reducer, alongside all effects.

Currently I have this in my reducer:

export interface State extends fromRoot.State {
    widgets: WidgetState;
}

//interface for the specific chunk of state for this reducer
export interface WidgetState {
    dashboardWidgets: Widget[];
    secondDashboardWidgets: Widget[];
    error: string;
}

//set the initial state for the properties in the chunk of state
const initialState: WidgetState = {
    dashboardWidgets: [],
    secondDashboardWidgets: [],
    error: ''
};

//---- selectors ----//

//createfeatureselector return the specific chunk of State from 'widgets', in this case WidgetState
const getWidgetFeatureState = createFeatureSelector<WidgetState>('widgets');

//so it's callable from the component export default.
//this function gets the createfeatureselector to look in the correct chunk and fetches the desired property from said chunk
export const getDashboardWidgets = createSelector(
    getWidgetFeatureState,
    state => state.dashboardWidgets
);

export const getError = createSelector(
    getWidgetFeatureState,
    state => state.error
);

//---- reducers ----//
//creates a copy of the state and adjusts it with the action.payload before changing the state
export function widgetReducer(state = initialState, action: WidgetActions): WidgetState {
    switch(action.type) {
        case WidgetActionTypes.DashboardWidgetAdded:
        return {
            ...state,
            dashboardWidgets: action.payload
        };
        case WidgetActionTypes.DashboardWidgetsLoadSuccess:
        return {
            ...state,
            dashboardWidgets: action.payload,
            error: ''
        }
        case WidgetActionTypes.DashboardWidgetsLoadFail:
        return {
            ...state,
            dashboardWidgets: [],
            error: action.payload
        }
        default:
        return state;
    }
}

and in my actions I have the following:

//create an enum for custom actions for easy accessibility
export enum WidgetActionTypes {
    DashboardWidgetAdded = '[Dashboard] Widget Added',
    DashboardWidgetsLoad = '[Dashboard] Load',
    DashboardWidgetsLoadSuccess = '[Dashboard] Load Success]',
    DashboardWidgetsLoadFail = '[Dashboard] Load Fail'
}

//create a class to create a new Action of each type listed in the ActionTypes 
export class DashboardWidgetAdded implements Action {
    readonly type = WidgetActionTypes.DashboardWidgetAdded;

    constructor(public payload: Widget[]) {}
}
export class DashboardWidgetsLoad implements Action {
    readonly type = WidgetActionTypes.DashboardWidgetsLoad;
}
export class DashboardWidgetsLoadSuccess implements Action {
    readonly type = WidgetActionTypes.DashboardWidgetsLoadSuccess;

    constructor(public payload: Widget[]) {}
}
export class DashboardWidgetsLoadFail implements Action {
    readonly type = WidgetActionTypes.DashboardWidgetsLoadFail;

    constructor(public payload: string) {}
}

//use the pipe symbol to pipe all actions together in 1 accessible point
export type WidgetActions = DashboardWidgetAdded 
| DashboardWidgetsLoad | DashboardWidgetsLoadSuccess | DashboardWidgetsLoadFail;

As you can see, at the moment I'd have to declare a new array in my state for each different use of my dashboard component.

I would like to be able to just declare this new array and all reducer actions from my component, so that I'd have something like:

this.store.dispatch(new widgetActions.CreateNewStateChunkIfNotExists('secondDashboard'));

Is there any way this can be done? Any help would be welcome.

回答1:

I interact with ngrx/store through a wrapper library (that I wrote), ng-app-state, so you may not be able to use this code exactly, but perhaps the general idea will give you inspiration.

When I have done things like this, I have the component that needs its own new slice of the store create and provide a new root level "store object". An equivalent without the wrapper library may be a feature module? It looks something like this:

interface DashboardState {
  // all the state needed for a single dashboard
  someText: string;
}

class DashboardStore extends AppStore<DashboardState> {
  constructor(ngrxStore: Store<any>) {
    super(ngrxStore, uniqId('dashboard'), makeInitialDashboardState());
  }
}

@Component({
  template: `<input [nasModel]="store('someText')">`,
  provides: [DashboardStore],
})
class Dashboard {
  constructor(public store: DashboardStore) {}
}

Then, whenever a dashboard component is on the page it creates its own space in the root store.

来源：https://stackoverflow.com/questions/55295590/how-to-add-state-properties-from-component