R Shiny: Remove Row Button in Data Table

Question

I'm working on a R Shiny app where a user has control of a data table. They can add new rows to the table, or remove any of the existing rows. My desire is to have a Remove button embedded in the table where the user can click this button and that row will be deleted.

Below is the current status of my solution, however it doesn't work consistently. The add button works consistently, however sometimes the remove button is not recognized.

Example failure.

• Load App
• Remove row 2
  • Works
• Remove row 1
  • Works
• Remove 3
  • Does not recognize that the button is pressed.

```

library(DT)

getRemoveButtons <- function(n, idS = "", lab = "Pit") {
  if (stringr::str_length(idS) > 0) idS <- paste0(idS, "-")
  ret <- shinyInput(actionButton, n,
                    'button_', label = "Remove",
                    onclick = sprintf('Shiny.onInputChange(\"%sremove_button_%s\",  this.id)' ,idS, lab))
  return (ret)
}
shinyInput <- function(FUN, len, id, ses, ...) {
  inputs <- character(len)
  for (i in seq_len(len)) {
    inputs[i] <- as.character(FUN(paste0(id, i), ...))
  }
  inputs
}

ui = shinyUI(fluidPage(
  fluidRow(DT::dataTableOutput("myTable")),
  fluidRow(actionButton("addRow", label = "Add Row",
                        icon = icon("plus"))))
)

server = function(input, output) {

  values <- reactiveValues()
  values$tab <- tibble(
    Row = 1:3L,
    Remove = getRemoveButtons(3, idS = "", lab = "Tab1"))

  proxyTable <- DT::dataTableProxy("tab")

  output$myTable <- DT::renderDataTable({
    DT::datatable(values$tab,
                  options = list(pageLength = 25,
                                 dom        = "rt"),
                  rownames = FALSE,
                  escape   = FALSE,
                  editable = TRUE)
  })

  observeEvent(input$remove_button_Tab1, {
    myTable <- values$tab
    s <- as.numeric(strsplit(input$remove_button_Tab1, "_")[[1]][2])
    myTable <- filter(myTable, row_number() != s)
    myTable <-
      mutate(myTable,
             Remove = getRemoveButtons(nrow(myTable), idS = "", lab = "Tab1"))
    replaceData(proxyTable, myTable, resetPaging = FALSE)
    values$tab <- myTable
  })
  observeEvent(input$addRow, {
    myTable <- isolate(values$tab)
    myTable <- select(myTable, Row)
    myTable <- bind_rows(
      myTable,
      tibble(Row = nrow(myTable) + 1))
    myTable <- mutate(myTable,
                      Remove = getRemoveButtons(nrow(myTable), idS = "", lab = "Tab1"))
    replaceData(proxyTable, myTable, resetPaging = FALSE)
    values$tab <- myTable
  })
}

shinyApp(ui = ui, server = server)

Answer 1

Ok, I have it working now. The issue was trying to reuse the ids for the buttons. By creating a counter and assigning each new button an id that's never been used before it now works perfectly. Modified code below.

```

library(DT)
library(dplyr)

getRemoveButton <- function(n, idS = "", lab = "Pit") {
  if (stringr::str_length(idS) > 0) idS <- paste0(idS, "-")
  ret <- shinyInput(actionButton, n,
                    'button_', label = "Remove",
                    onclick = sprintf('Shiny.onInputChange(\"%sremove_button_%s\",  this.id)' ,idS, lab))
  return (ret)
}

shinyInput <- function(FUN, n, id, ses, ...) {
  as.character(FUN(paste0(id, n), ...))
}

ui = shinyUI(fluidPage(
  fluidRow(DT::dataTableOutput("myTable")),
  fluidRow(actionButton("addRow", label = "Add Row",
                        icon = icon("plus"))))
)

server = function(input, output) {

  buttonCounter <- 3L

  values <- reactiveValues()
  values$tab <- tibble(
    Row = 1:3L,
    id = 1:3L) %>%
    rowwise() %>%
    mutate(Remove = getRemoveButton(id, idS = "", lab = "Tab1"))

  proxyTable <- DT::dataTableProxy("tab")

  output$myTable <- DT::renderDataTable({
    DT::datatable(values$tab,
                  options = list(pageLength = 25,
                                 dom        = "rt"),
                  rownames = FALSE,
                  escape   = FALSE,
                  editable = TRUE)
  })

  observeEvent(input$remove_button_Tab1, {
    myTable <- values$tab
    s <- as.numeric(strsplit(input$remove_button_Tab1, "_")[[1]][2])
    myTable <- filter(myTable, id != s)
    replaceData(proxyTable, myTable, resetPaging = FALSE)
    values$tab <- myTable
  })
  observeEvent(input$addRow, {
    buttonCounter <<- buttonCounter + 1L
    myTable <- isolate(values$tab)
    myTable <- bind_rows(
      myTable,
      tibble(Row = nrow(myTable) + 1) %>%
        mutate(id = buttonCounter,
               Remove = getRemoveButton(buttonCounter, idS = "", lab = "Tab1")))
    replaceData(proxyTable, myTable, resetPaging = FALSE)
    values$tab <- myTable
  })
}

shinyApp(ui = ui, server = server)