angular - NgRx: 得到 'You provided ' undefined' where a stream is expected.'当调用有效的完整 Action 时

Question

我正在尝试执行 API 调用并将现有数据与现有数据合并(合并是在 addMissingData 中完成的)。
当我尝试调用时出现错误:

Uncaught TypeError: You provided 'undefined' where a stream wasexpected. You can provide an Observable, Promise, Array, or Iterable.

at subscribeTo (subscribeTo.js:27)at subscribeToResult (subscribeToResult.js:11)at MergeMapSubscriber._innerSub (mergeMap.js:59)at MergeMapSubscriber._tryNext (mergeMap.js:53)at MergeMapSubscriber._next (mergeMap.js:36)at MergeMapSubscriber.next (Subscriber.js:49)at MapSubscriber._next (map.js:35)at MapSubscriber.next (Subscriber.js:49)at CatchSubscriber._next (Subscriber.js:72)at CatchSubscriber.next (Subscriber.js:49)

 GetStepWiseMasterData$ = createEffect(() => this.actions$.pipe(
            ofType(MasterDataAction.getCustomerMasterData),
            switchMap((action) => {
                return this.dataService.GetDataAsync(action.stepEnum).pipe(
                    map((response) => {
                        return {
                            isSuccess: response.isSuccess,
                            newData: response.data,
                            data: action.data,
                        };
                    }),
                    mergeMap((response) => {
                        if (response.isSuccess) {
                            this.addMissingData(response.newData, action.data).then(result => {
                                return [DataAction.getCustomerDataComplete({ customerData: result })];
                            });
                        } else {
                            return [DataAction.getCustomerDataFailed({ customerData: {} })];
                        }
                    }),
                    catchError(() => EMPTY)
                );
            })
        ));

   async addMissingData(newMasterData: BusinessPartnerMasterDataVM, existingMasterData: BusinessPartnerMasterDataVM = {}): Promise<any> {
        const omitNullValues = masterDataObj => new Promise((resolve) => {
            // filter with property name and delete all properties that are null
            Object.keys(masterDataObj).filter(propertyName => masterDataObj[propertyName] === null).forEach(propertyName => delete(masterDataObj[propertyName]));
            resolve(masterDataObj);
        });
        const masterNew = await omitNullValues(newMasterData);
        const masterOld = await omitNullValues(existingMasterData);
        const ret = Object.assign({}, masterNew, masterOld);
        return ret;
    }

Answer 1

好像你的问题发生在这个区域，

mergeMap((response) => {
    if (response.isSuccess) {
        this.addMissingData(response.newData, action.data).then(result => {
            return [DataAction.getCustomerDataComplete({ customerData: result })];
        });
    } else {
        return [DataAction.getCustomerDataFailed({ customerData: {} })];
    }
})

这里没有任何返回 if (response.isSuccess)条件分支。据我了解，您想调用两个 API

第一个电话getCustomerMasterData

然后使用 getCustomerMasterData 的结果，您要调用addMissingData

我的建议是创建另一个函数来调用上面的 apis，然后使用管道。

GetStepWiseMasterData$ = createEffect(() => this.actions$.pipe(
    ofType(MasterDataAction.getCustomerMasterData),
    switchMap((action) => {
        return from(this.combinedFunction(action)).pipe(
            map((result) => {
                return { masterData: result };
            }),
            switchMap((result) => {
                return [MasterDataAction.getCustomerDataComplete(result)];
            })
        );
    })
));

async combinedFunction(action) {
    const response = await this.dataService.GetDataAsync(action.stepEnum).toPromise();
    if (!response.isSuccess) {
        return {};
    }
    return await this.addMissingData(response.newData, action.data);
}

from需要将 Promise 转换为可以从 rxjs 导入的 Observable ，或者您可以修改 combinedFunction返回一个 Observable。
希望这有帮助:)