Writing and Saving to excel file with Shiny - r

Question

My app allows a user to input a date range, a division, a pdf file, and an excel file. The program pulls numbers from the pdf, calculates total points, and adds it to the ranks pulled from the existing excel file. It is supposed to write and save the excel file. Without Shiny, my program works fine. Within Shiny, It is running and the data is correct, but it does not add the data to the excel file. I have added print prompts at various stages to test this. I have tried running this externally as well with the same results. It does not throw an error, it just not add the data to the excel file.
Server function
server<-function(input,output){
output$horse_div <- renderText({
paste("You have chosen",input$division)
})
output$qualifying<-renderText({
paste("Qualifying Period from",input$date[1],"to",input$date[2])
})
output$pdf<-renderText({
req(input$horsereport)
req(input$excelfile)
ponyoutput<-horseRecord(input$horsereport$datapath,input$date[1],input$date[2],input$division,input$excelfile$datapath)
paste("mylist",ponyoutput[1])
})
}
Snippet of horseRecord function
#Set up sheet and excel file
wsheetrank<-paste(div,"RANK")
wsheetpoints<-paste(div,"POINTS")
#load workbook
wb<-loadWorkbook(file=excelfile)
#add pony to ranked list
rank<-read.xlsx(excelfile,wsheetrank)
rank<-rank[,2:3]
rank<-rank %>% mutate(Points=as.numeric(Points))
dat<-rank
dat<-dat%>% add_row(Pony=horse,Points=points) %>% arrange(desc(Points))
#remove duplicates
dat<-dat[!duplicated(dat$Pony),]
rownames(dat)<-seq(from=1,to=nrow(dat),by=1)
#find rank
rank<-grep(horse,dat$Pony)
#Write to excel file
writeData(wb,sheet=wsheetrank,x=dat,colNames=TRUE,rowNames = TRUE,borders="all")
saveWorkbook(wb,excelfile,overwrite=TRUE)
This should add the totaled points pulled from the PDF file to the ranked list, resort, and write to the ranked worksheet. The full code and files can be found here: https://github.com/chealy21/horsePoints

Answer 1

The excel file that you upload gets saved in a temporary file on the shiny server. It is not the excel file that is on disk, even if you run your app locally.
If you add a browser() before writing the data in the workbook (line 138 of horsereportfunction.R), you will get a console prompt when the app reaches that line and you will be able to see it for yourself.
This is what is in the excelfile variable (on a linux machine. Windows temp file are somewhere else but they are still just tmp files):
excelfile
# [1] "/tmp/RtmpFllCQq/5709c4b043babf5b85bd29b4/0.xlsx"
This temporary file on the shiny server does get updated:
readxl::read_excel("/tmp/RtmpFllCQq/5709c4b043babf5b85bd29b4/0.xlsx") %>% filter(Pony == "BIT OF LAUGHTER")
# # A tibble: 1 x 3
# ..1 Pony Points
# <chr> <chr> <dbl>
# 1 30 BIT OF LAUGHTER 1503.
This is in line with the documentation for fileInput:
Whenever a file upload completes, the corresponding input variable is set to a dataframe. This dataframe contains one row for each selected file, and the following columns:
name:
The filename provided by the web browser. This is not the path to read to get at the actual data that was uploaded (see datapath column).
size:
The size of the uploaded data, in bytes.
type:
The MIME type reported by the browser (for example, text/plain), or empty string if the browser didn't know.
datapath:
The path to a temp file that contains the data that was uploaded. This file may be deleted if the user performs another upload operation.
Maybe you could let the user download the updated report (from datapath) after updating it?
If you never intend to publish your app and will always use it locally, you could hardcode the excel file directory. Your app would then copy the workbook at the hardcoded location from datapath.