如何為Angular ngrx商店制作一個“reducer enhancer”來進行撤銷/重做

Question

我想為特定的商店切片添加reducer Enhancer或meta reducer。 我已經實現了一個接收reducer並啟用撤消/重做功能的函數。 它目前看起來像這樣：

export const adminReducers: ActionReducerMap<AdminFeatureState> = {
    admin: admin.reducer,
    dynamicForm: undoable(dynamicForm.reducer, DynamicFormActionTypes.UNDO, DynamicFormActionTypes.REDO, [
        DynamicFormActionTypes.SELECTED_DYNAMIC_CONTROLS_CHANGED,
        DynamicFormActionTypes.CHANGE_GROUP,
        DynamicFormActionTypes.RESET,
        DynamicFormActionTypes.ADD_PAGE,
        DynamicFormActionTypes.REMOVE_PAGE,
        DynamicFormActionTypes.REORDER_GROUPS,
        DynamicFormActionTypes.SAVE_EDIT_CONTROL
    ])
};

export function undoable<T>(reducer: ActionReducer<any>, undoActionType: string, redoActionType: string, recordedActions: string[]): ActionReducer<any> {
    // Call the reducer with empty action to populate the initial state
    const initialState: UndoableState<T> = {
        past: [],
        present: reducer(undefined, { type: 'INIT' }),
        future: []
    };

    // Return a reducer that handles undo and redo
    return function (state = initialState, action) {
    ...
    };
}

一切都很好，除非我為生產而構建時出現以下錯誤：

Error during template compile of 'AdminModule'
  Function calls are not supported in decorators but 'undoable' was called in 'adminReducers'
    'adminReducers' calls 'undoable' at src\app\core\containers\admin\admin-feature.reducers.ts(11,29).

我看到你可以增強現有reducer的唯一另一種方法是使用meta-reducers，但是每個reducer函數調用它們，而不僅僅是特定的一個，例如本例中的'dynamicForm'。

Answer 1

在對文檔進行了一些挖掘之后，我在這里找到了解決方案：

https://github.com/ngrx/platform/blob/master/docs/store/api.md#feature-module-reducers-and-aot

你可以簡單地在combineReducers中包裝'adminReducers'，如下所示：

const adminReducers: ActionReducerMap<AdminFeatureState> = {
    admin: admin.reducer,
    dynamicForm: undoable(dynamicForm.reducer, DynamicFormActionTypes.UNDO, DynamicFormActionTypes.REDO, [
        DynamicFormActionTypes.SELECTED_DYNAMIC_CONTROLS_CHANGED,
        DynamicFormActionTypes.CHANGE_GROUP,
        DynamicFormActionTypes.RESET,
        DynamicFormActionTypes.ADD_PAGE,
        DynamicFormActionTypes.REMOVE_PAGE,
        DynamicFormActionTypes.REORDER_GROUPS,
        DynamicFormActionTypes.SAVE_EDIT_CONTROL
    ])
};

const adminMetaReducer = combineReducers(adminReducers);

export function enhancedAdminReducers(state, action) {
    return adminMetaReducer(state, action);
}

然后將其導入您的模塊

StoreModule.forFeature(ADMIN_FEATURE, enhancedAdminReducers),