IBrokers: Looping through a dataframe of endDateTime and twsEquity parameter pairs for reqHistoricalData in r

Question

I am having some difficulty get the following reqHistoricalData request in IBrokers to work. I am try to feed a data frame of date time and stock tickers pair to retrieve the intraday tickers at 5 minute intervals for historical research. I am looking to retrieve specific pair of stock ticker and a date. I can get this to work on a manual input but I have a data frame of 950 of these to do and want to make this work in a loop. This done in r using the IBrokers package

Manual example that works

conn <- twsConnect()

stock_dat = reqHistoricalData(conn, twsSTK("XEC"), endDateTime = "20191223 16:00:00",  duration = "1 D", barSize = '5 mins') 

the "XEC" and "20191223 16:00:00" are as.character and returns an object xts object for that day.

My sample data for this example would be a data frame called PoDHist and has 2 columns with 4 observations

Stock   END_Date_Time
SYY     20191206 16:00:00
JNJ     20191209 16:00:00
OMC     20191210 16:00:00
MOS     20191213 16:00:00 

both columns are as.characters

I am trying to use a pmap function from purrr

bar_downloader <- function(Stock,endDateTime)
{
    n=PoDHist2 %>%
        five_min_bar_data = reqHistoricalData(conn, twsEquity=PoDHist2$Stock, endDateTime = PoDHist2$END_Date_Time, duration = "1 D", barSize = '5 mins') %>%
            print(Stock)
} 

pmap(list(PoDHist2$Stock),list(PoDHist2$END_Date_Time),bar_downloader)

I am getting an error

Error in 1:nrow(PoDHist2$Stock) : argument of length 0

I am also seeing some inconsistence in the input format for endDateTime. The IBrokers r package specifies as format as ’CCYYMMDD HH:MM:SS TZ’. However I was manually able to get this to work in YYMMDD HH:MM:SS format as a character and not a time object.

Any suggestions would be helpful