How to resolve Promise using async/await function?

Question

I have try and catch once that is resolved my code is not reaching to last return Promise.resolve(returnValue) and throwing empty {} object , Any help will be appreciated to resolve below issue.

main.ts

private async combineData(data: any, request: any): Promise < any > {
    const details: any = [];
    const indexIDs = this.indexIDs;
    delete data.header.IndexOfRequestThatFailed;
    const returnValue = {
        "header": {
            "statusDesc": "",
            "statusCode": "",
            "refID": ""
        },
        "details": details
    }
    as IGetPaymentHistoryResponse;
    const paymentHistoryDetails = {
        header: returnValue.header,
        details: returnValue.details
    };
    // saving details to cache
    const saveDetails = {}
    as ICacheRequest;
    saveDetails.cacheobject = paymentHistoryDetails;
    saveDetails.cachetype = "CombinedPaymentHistoryCache";
    saveDetails.key =
    request.body.getPaymentHistoryRequest.header.serviceContext.tokenID;

    const _passedParams: ILogParams = {}
    as ILogParams;
    _passedParams.refId =
    request.body.getPaymentHistoryRequest.header.serviceContext.refID;
    _passedParams.sessionId =
    request.body.getPaymentHistoryRequest.header.serviceContext.tokenID;
    _passedParams.opname = "getPaymentHistory";
    _passedParams.starttime = moment().toString();
    _passedParams.endtime = "";

    try {
        await CacheController.getInstance().saveDetailsWrapper(saveDetails,
            _passedParams);
        return Promise.resolve({
            getPaymentHistoryResponse: paymentHistoryDetails
        });
    } catch (err) {

        return Promise.reject({
            getPaymentHistoryResponse: err
        });
    }
    return Promise.resolve(returnValue);

}

Answer 1

Use simple return statement as async function returns Promise by default. So your returned value is equal to resolving a value, and throwing is rejection

try {
        await CacheController.getInstance().saveDetailsWrapper(saveDetails,
            _passedParams);
        return {
            getPaymentHistoryResponse: paymentHistoryDetails
        };
    } catch (err) {
        throw {
            getPaymentHistoryResponse: err
        };
    }

Code will not reach last line because there is a return statement in try and catch.

It is like you write

if(check) {... return 1}
else {return 2}
return 3

And ask why 3 is never returned

Update

I understood :) So async/await gives you ability to write asynchronous code in a sync way. If you want to make a request without blocking other code then just use plain then able syntax:

private combineData(data: any, request: any): any {
    const details: any = [];
    const indexIDs = this.indexIDs;
    delete data.header.IndexOfRequestThatFailed;
    const returnValue = {
        "header": {
            "statusDesc": "",
            "statusCode": "",
            "refID": ""
        },
        "details": details
    }
    as IGetPaymentHistoryResponse;
    const paymentHistoryDetails = {
        header: returnValue.header,
        details: returnValue.details
    };
    // saving details to cache
    const saveDetails = {}
    as ICacheRequest;
    saveDetails.cacheobject = paymentHistoryDetails;
    saveDetails.cachetype = "CombinedPaymentHistoryCache";
    saveDetails.key =
    request.body.getPaymentHistoryRequest.header.serviceContext.tokenID;

    const _passedParams: ILogParams = {}
    as ILogParams;
    _passedParams.refId =
    request.body.getPaymentHistoryRequest.header.serviceContext.refID;
    _passedParams.sessionId =
    request.body.getPaymentHistoryRequest.header.serviceContext.tokenID;
    _passedParams.opname = "getPaymentHistory";
    _passedParams.starttime = moment().toString();
    _passedParams.endtime = "";

    // do not return here to return on the last line
    CacheController.getInstance().saveDetailsWrapper(saveDetails, _passedParams).then(response => ..., err => ...);
    return returnValue;

}