I am working on a shiny application that allows users to enter comments about an observation. The comments are then saved in a SQL database on the back end. The code below is a working representation of my current application.
What is happening is the tables load with the subset of Cylinder = 4 (the radio buttons), the user can save comments, got to Cylinder = 6, save comments, and then Cylinder = 8, and save comments. But if I ever change the cylinder back to a value that I've already saved comments at, the text inputs are unbound and no comments are saved. In order to restore the functionality, I have to restart the application. I've found that irritates my users.
What do I need to do to make sure I can continue to save comments if I go back to a Cylinder value I've already used?
I'm sorry that it isn't a very concise example. When you enter a comment, the console will print the number of comments saved, and display the data frame that was altered so you can compare what is showing in the application.
library(shiny)
library(DT)
library(dplyr)
mtcars$comment <- rep("", nrow(mtcars))
mtcars$row_id <- seq_len(nrow(mtcars))
AppData <- split(mtcars, mtcars[c("cyl", "am")])
# Makes a text input column out of a data frame
make_inputtable <- function(df){
df$comment <-
mapply(
function(comment, id){
as.character(textInput(inputId = sprintf("txt_comment_%s", id),
label = "",
value = comment))
},
comment = df$comment,
id = df$row_id,
SIMPLIFY = TRUE)
df
}
ui <- shinyUI(
fluidPage(
radioButtons(inputId = "rdo_cyl",
label = "Cylinders",
choices = sort(unique(mtcars$cyl)),
inline = TRUE),
h3("Automatic"),
actionButton(inputId = "btn_save_automatic",
label = "Save Comments"),
DT::dataTableOutput("am0"),
hr(),
h3("Manual"),
actionButton(inputId = "btn_save_manual",
label = "Save Comments"),
DT::dataTableOutput("am1"),
# unbind a datatable. Needs to be done before a table is redrawn.
tags$script(HTML(
"Shiny.addCustomMessageHandler('unbind-DT', function(id) {
Shiny.unbindAll($('#'+id).find('table').DataTable().table().node());
})"))
)
)
server <- shinyServer(function(input, output, session){
reactiveData <- reactiveValues(
am0_cyl4 = AppData[["4.0"]],
am0_cyl6 = AppData[["6.0"]],
am0_cyl8 = AppData[["8.0"]],
am1_cyl4 = AppData[["4.1"]],
am1_cyl6 = AppData[["6.1"]],
am1_cyl8 = AppData[["8.1"]]
)
# Reactive Objects ------------------------------------------------
ref0 <- reactive({
sprintf("am0_cyl%s", input$rdo_cyl)
})
data0 <- reactive({
reactiveData[[ref0()]]
})
ref1 <- reactive({
sprintf("am1_cyl%s", input$rdo_cyl)
})
data1 <- reactive({
reactiveData[[ref1()]]
})
# Event Observers -------------------------------------------------
observeEvent(
input$btn_save_automatic,
{
in_field <- names(input)[grepl("^txt_comment_", names(input))]
in_field_id <- sub("^txt_comment_", "", in_field)
in_field_id <- as.numeric(in_field_id)
in_field_id <- in_field_id[in_field_id %in% data0()$row_id]
exist_frame <- data0()[c("row_id", "comment")]
new_frame <-
data.frame(
row_id = in_field_id,
comment = vapply(in_field_id,
function(id){ input[[sprintf("txt_comment_%s", id)]]},
character(1)),
stringsAsFactors = FALSE)
Compare <- left_join(exist_frame,
new_frame,
by = "row_id",
suffix = c("_exist", "_new")) %>%
filter(comment_exist != comment_new)
message(sprintf("* %s comment(s) saved", nrow(Compare)))
# Only perform the save operations if there are changes to be made.
if (nrow(Compare)){
session$sendCustomMessage("unbind-DT", "am0")
for(i in seq_len(nrow(Compare))){
row <- Compare$row_id
reactiveData[[ref0()]]$comment[reactiveData[[ref0()]]$row_id == row] <-
input[[sprintf("txt_comment_%s", row)]]
}
print(data0())
}
}
)
# Very similar to btn_save_automatic
observeEvent(
input$btn_save_manual,
{
in_field <- names(input)[grepl("^txt_comment_", names(input))]
in_field_id <- sub("^txt_comment_", "", in_field)
in_field_id <- as.numeric(in_field_id)
in_field_id <- in_field_id[in_field_id %in% data1()$row_id]
exist_frame <- data1()[c("row_id", "comment")]
new_frame <-
data.frame(
row_id = in_field_id,
comment = vapply(in_field_id,
function(id){ input[[sprintf("txt_comment_%s", id)]]},
character(1)),
stringsAsFactors = FALSE)
Compare <- left_join(exist_frame,
new_frame,
by = "row_id",
suffix = c("_exist", "_new")) %>%
filter(comment_exist != comment_new)
message(sprintf("* %s comment(s) saved", nrow(Compare)))
# Only perform the save operations if there are changes to be made.
if (nrow(Compare)){
session$sendCustomMessage("unbind-DT", "am0")
for(i in seq_len(nrow(Compare))){
row <- Compare$row_id
reactiveData[[ref1()]]$comment[reactiveData[[ref1()]]$row_id == row] <-
input[[sprintf("txt_comment_%s", row)]]
}
print(data1())
}
}
)
# Output Objects --------------------------------------------------
output$am0 <-
DT::renderDataTable({
make_inputtable(data0()) %>%
datatable(escape = -13,
options = list(preDrawCallback = DT::JS('function() { Shiny.unbindAll(this.api().table().node()); }'),
drawCallback = DT::JS('function() { Shiny.bindAll(this.api().table().node()); } ')))
})
output$am1 <-
DT::renderDataTable({
make_inputtable(data1()) %>%
datatable(escape = -13,
options = list(preDrawCallback = DT::JS('function() { Shiny.unbindAll(this.api().table().node()); }'),
drawCallback = DT::JS('function() { Shiny.bindAll(this.api().table().node()); } ')))
})
})
shinyApp(ui = ui, server = server)
Edits and updates
editable data tables are a potential solution, but would require upgrading our package library. We are currently using R 3.4.1 with shiny 1.0.4 and DT 0.2.12.
Yes, that's comparatively ancient. But the cost of upgrading is substantial given the sensitivity of the reports supported by this application and the quality assurance required by any upgrade.