R Shiny: small table with checkbox columns and a scrollbar

Question

I am trying to make a Shiny app using golem, but I am very new to this. This time I just want to make a small table with checkboxes and a scroll bar, but I am not succeeding...

This is the only thing I manage to make work so far (but even the scrollbar does not seem to show):

mod_saving_side_ui <- function(id){
  ns <- NS(id)
  tagList(
    shinyjs::useShinyjs(),
    shinyalert::useShinyalert(),

    fluidRow(
      DT::DTOutput(ns("my_marker_table"), width = "75%")
    )
 
  )
}


mod_saving_side_server <- function(id, r){
  moduleServer( id, function(input, output, session){
    ns <- session$ns

    output$my_marker_table <- DT::renderDT({
      marker_df <- data.frame(marker=LETTERS, positive="", negative="")
      marker_df$positive[1] <- "y"
      marker_df$negative[2:4] <- "y"
      marker_matrix <- as.matrix(marker_df)
      
      DT::datatable(marker_matrix, options = list(scrollY = TRUE, sDom  = '<"top">rt<"bottom">ip'), rownames = FALSE)
    })
    
  })
}

It produces this:

However I would like to accomplish 3 things:

1. Have a scrollbar instead of the Previous 1 2 3 Next buttons
2. Make the positive and negative columns have a checkbox per row
3. Have the positive checkbox preselected for the first row A , and the negative checkbox preselected for the 2:4 rows B , C , D

How to make checkboxGroupInput work in here and the scrollbar to show? Thanks!

Answer 1

Here's a partial answer, only focused on point 1. I think you should split this post into several ones, it's a bit discouraging when we see a list of things to do instead of a single question.

Also, your example is not reproducible (we can't just copy-paste your code to make the app), so I made a basic app instead.

Basically, I remove the "1", "2", "3", etc. buttons at the bottom of the datatable() with the argument pageLength . Only doing this produces a very long table, so I use CSS to specify its height (here I put 15em but it's your choice) and to make it scrollable.

library(shiny)
library(DT)

ui <- fluidPage(
  tags$head(
    tags$style(
      HTML(
        "#test {
          height: 15em !important;
          overflow-y: scroll
        }"
      )
    )
  ),
  DTOutput("test")
)

server <- function(input, output, session) {
  
  output$test <- renderDT({
    datatable(iris, options = list(
      pageLength = nrow(iris)
    ))
  })
  
}

shinyApp(ui, server)