NgRx: get '您提供了 'undefined' 预期流的位置。有效调用完整操作时

Question

我正在尝试执行 API 调用并将现有数据与现有数据合并（合并在 addMissingData 中完成）。当我尝试调用 :

时出现错误

Uncaught TypeError: You provided 'undefined' where a stream was expected. 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

您的问题似乎出在这方面，

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

此处 if (response.isSuccess) 条件分支中没有任何内容 return。据我了解，您想调用两个 API，它们是

第一次通话getCustomerMasterData
然后使用 getCustomerMasterData 的结果，你想调用 addMissingData

我的建议是创建另一个函数在 api 之上调用，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 转换为可从 rxjs 导入的 Observable，或者您可以将 combinedFunction 修改为 return 一个 Observable。

希望这对您有所帮助:)

NgRx: get '您提供了 'undefined' 预期流的位置。有效调用完整操作时

NgRx: get 'You provided 'undefined' where a stream was expected.' when calling complete action in effect

angular

typescript

rxjs

ngrx

ngrx-store