Keep formatting when exporting table with DT (DataTables buttons extension)

shiny
dt

#1

Hello,

I made a shiny app where someone uploads a file, some ratios are computed, and those ratios can be formatted using sliders for thresholds. I use DT::formatStyle for this and it is working really fine.

Then, I want to export the data, using the buttons extension in DT. I want to keep the formatting when exporting to pdf or printing. It turns out that this doesn’t work: the data is exported without any formatting. I tried to set exportOptions(list(stripHtml = FALSE)), but it still doesn’t work.

What surprises me as well, is that even when I print directly from Firefox (I have tried with Firefox only, and the app will only be run in Firefox), the color is dropped, but font weight is kept. I suspect that I may have to tweak the CSS but I do not know how to do that.

I would like to have a way to make the pdf and/or the print “as is”, the closest to what I see in the browser.
Below is a reprex:

library(shiny)
library(DT)
library(dplyr)
data("starwars")

ui <- fluidPage(title = "Ratios",
  sidebarLayout(
    sidebarPanel(width = 2,
                 actionButton("button", "Go"), # Emulates data loading
                 sliderInput("seuil_j", "Threshold J",
                             min = 0,  max = 80, value = 35, step = 0.5)),
    mainPanel( 
      fluidRow(column(width = 12,
                      DT::dataTableOutput("ratios"))))
  )
)

server <- function(input, output, session) {
  donnees_ratios <- reactive({
    req(input$button)
    set.seed(14)
    starwars %>% 
      select(1:10) %>% # DataTables is not happy with list columns
      mutate(signe = sample(c(1, -1), replace = TRUE, size = nrow(.)),
             ratio_j = signe * mass / height) %>% 
      select(name, mass, height, signe, ratio_j, everything())
  })
  
  output$ratios <- DT::renderDataTable({
    donnees_ratios() %>% 
      creer_DT() %>% 
      formatter_DT(input)
  })
}

creer_DT <- function(donnees) {
  datatable(donnees, 
            rownames = FALSE, 
            class = 'cell-border stripe compact hover',
            extensions = c("Buttons"),
            options = list(
              dom = 'Blfrtip',
              buttons = list(
                list(extend = "pdf", 
                     exportOptions = list(stripHtml = FALSE,
                                                     columns = ':visible'),
                     orientation = 'landscape'),
                list(extend = "print", 
                     exportOptions = list(stripHtml = FALSE,
                                          columns = ':visible')),
               "excel", "csv", "colvis"),
              language = list(
                decimal = ",",
                thousands = "&#8239;"  # small unbreakable space
              )
            )
  )
}

formatter_DT <- function(table, input) {
  table %>% 
    formatPercentage(columns = c("ratio_j"),
                     digits = 1L, dec.mark = ",", mark = "&#8239;") %>%
    formatRound(columns = c("height", "mass"),
                digits = 1L, dec.mark = ",", mark = "&#8239;") %>%
    format_seuil("ratio_j", input$seuil_j)
}

format_seuil <- function(table, column, seuil) {
  # Threshold for the aboslute value, and different coloring if higher or lower
  formatStyle(table, column, 
              fontWeight = styleInterval(
                c(-seuil / 100, seuil / 100), c("bold", "normal", "bold")),
              color = styleInterval(
                c(-seuil / 100, seuil / 100), c("red", "black", "orange")
              ))
}

shinyApp(ui, server)

I hope that is clear and thanks for helping!

Florian


#2

In case anybody is interested, I asked the question on StackOverflow, and the answer is that it is not easy. I actually ended up doing it outside of DT.
Here is the link