How to override (upon actionButton click) a reactive object in R Shiny Flexdashboard

Question

Am trying to make an R Shiny Flexdashboard that allows the user to utilise either a local Excel file or a downloaded Googlesheet, as a data source.

I have created an example here but I have used a local csv file to stand in place for the Googlesheets download component (using googlesheets in the example would be complicated).

https://gist.github.com/jtag04/67ae6b2c39e4f68f90e06bb1ce2ceb98

The script above works (save this as an *.rmd file for it to run -it's a Flexdashboard).

However, my challenge is that I want the *csv upload (when the actionButton is pressed) to override the Excel file object (if it exists).

i.e instead of saving the csv to step_one_2 (as in the example), for it to override the step_one object (if it exists).

Is this possible? Many thanks in advance.

Answer 1

One way to achieve something like this (if I understand everything correctly) would be to use radioButtons to let the user choose the input type. Then render a different input element dependent on user choice, and have a reactive that deals with the two different input file types appropriately. At the end, we are rendering a single table, either from excel or googlesheets file.

Code:

library(shiny)
library(tidyverse)

# let the user choose the type of input file
radioButtons(
  inputId = "what_source",
  label = "Choose source file",
  choices = c("googlesheets", "excel"),
  inline = FALSE
  )

# render file input widgets conditioned on user choice
conditionalPanel(condition = 'input.what_source == "googlesheets"',
                 fileInput("google_file", "Upload from csv", accept = ".csv")
                 )

conditionalPanel(condition = 'input.what_source == "excel"',
                 fileInput("excel_file", "Upload from excel", accept = ".xlsx")
                 )

# deal with the file selected by the user
what_file <- reactive({
  if (input$what_source == "googlesheets") {
    x <- readr::read_csv(input$google_file$datapath) %>% mutate(source = "csv")
  } else {
    x <- readxl::read_excel(input$excel_file$datapath) %>% mutate(source = "Excel")
  return(x)
  }
})

# then in a different element downstream add the render function:
renderDataTable(what_file())

---

Update: Fetch csv at will, but change to excel input with checkbox:

Server logic:

# fetch updated csv data
actionButton("fetch", "Fetch new data")
checkboxInput("excel", label = "Get excel file", value = FALSE)

fetch_new <- eventReactive(input$fetch, {
  readr::read_csv("df.csv")
})

conditionalPanel(condition = 'input.excel == true',
                 fileInput("excel_file", 
                           "Upload from excel", 
                            accept = ".xlsx")
                 )

what_file <- reactive({
  if (!input$excel) {
    x <- fetch_new()
  } else {
    x <- readxl::read_excel(input$excel_file$datapath)
  return(x)
  }
})