CODEWITHSUNDEEP
rshiny
CallumH
CallumH

Reputation: 779

How to Update a Shiny checkboxGroupInput

As a way to understand Shiny I am developing a small game for multiple players.

I import a csv to retrieve my eligible players (players.csv) and also include a tab with a textInput and actionButton to incrementally add other eligible players as time passes.

My next step is to then select from these eligible players those who wish to play a given game. I offer this functionality as a checkboxGroupInput on the subsequent tabPanel. I have not considered in this query using the players, or indeed the game, any further at this time.

My issue however is that if I add a new player in the first step i can't seem to update the checkboxGroupInput options to reflect any players i have just added in the first step.

For the avoidance of doubt...

QUESTION - How do i force the checkboxGroupInput to also show the new player I just added?

I have nibbled at various different solutions without much success, including trying to make good on updateCheckboxGroupInput or through conditionalPanel.

Here's my working code and a big dose of thanks for your opinions. :)

library(shiny)


##########################  SETUP
file_path = "C:/Users/Callum Hollywood/Desktop/"
write.table(data.frame(player = c("john", "paul", "george", "ringo")),
        paste0(file_path, "players.csv"),
        col.names = T,
        row.names = F,
        sep = ",")
read_in_players = read.table(paste0(file_path, "players.csv"), header = T, stringsAsFactors = F, sep = ",")$player


########################## UI
ui = fluidPage(
navlistPanel(
tabPanel("add_a_player", 
         "add a player to the list of eligible players", 
         textInput("addplayer", ""),
         actionButton("submit", "SUBMIT")

),
tabPanel("play_game",
  checkboxGroupInput(inputId = "add_players",
                     label = "add players to a current game",
                     choices = read_in_players))))


##########################  SERVER
server = function(input, output){

players = eventReactive(input$submit,{input$addplayer}) 

observeEvent(input$submit,{
write.table(players(), paste0(file_path, "players.csv"), col.names = F, row.names = F, sep = ",", append = T)
})}

shinyApp(ui, server)

Upvotes: 0

Views: 1183

Answers (1)

SBista
SBista

Reputation: 7704

You can use updateCheckboxGroupInput as follows:

server = function(input, output,session){

      players = eventReactive(input$submit,{input$addplayer}) 

      observeEvent(input$submit,{
        write.table(players(), paste0(file_path, "players.csv"), col.names = F, row.names = F, sep = ",", append = T)
        updateCheckboxGroupInput(session, inputId = "add_players", 
                                 choices = read.table(paste0(file_path, "players.csv"), header = T, stringsAsFactors = F, sep = ",")$player )

      })}

But since reading the csv file every time you add a player is not a good idea, you could instead use reactiveValues as follow:

 server = function(input, output,session){
      Allplayers=reactiveValues(Val = read_in_players)

      players = eventReactive(input$submit,{input$addplayer}) 

      observeEvent(input$submit,{
        write.table(players(), paste0(file_path, "players.csv"), col.names = F, row.names = F, sep = ",", append = T)
        Allplayers$Val <- c( Allplayers$Val,players())
        updateCheckboxGroupInput(session, inputId = "add_players", choices = Allplayers$Val)

      })}

Upvotes: 2

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