Disable selectinput once user selected multiple choices in R shiny-CodePudding

I have a selectinput with multiple = TRUE, I need to disable the selectinput once user select the multiple choices. But the selectinput is disabling once I select the first choice and it is not allowing me to select second choice. I have used following code.

library(shiny)
library(shinyjs)

ui <- fluidPage(
  br(),
  useShinyjs(),
  fluidRow(
    column(
      width = 6,
      selectInput(inputId = "check1", label = "Choose", choices = c("choice A","choice B","choice C"),multiple = T),
      verbatimTextOutput(outputId = "res1")
    )
  )
)
server <- function(input, output, session) {
  
  flag_lifecycle <- reactiveValues(val = "Yes")
  
  output$res1 <- renderPrint({
    input$check1
  })
  
  observeEvent(input$check1, {
    shinyjs::disable("check1")
  })
  
}
shinyApp(ui = ui, server = server)

The output I got

Here, selectinput should be disabled only when multiple choice has been selected.

Any help here is appreciated. Thanks in advance!

CodePudding user response：

In the current setup you don't actually know when user has finished the selection.

Consider various scenarios -

If you disable after 1st selection then user cannot select 2 or 3 values.
If you disable after 2nd selection then user cannot select 3 values.
If you disable after 3rd then what if user only want to select 1 value ?

You'll never know when to disable based on length of values. I think a better option would be to provide an actionButton for user to submit after they are done with their selection.

library(shiny)
library(shinyjs)

ui <- fluidPage(
  br(),
  useShinyjs(),
  fluidRow(
    column(
      width = 6,
      selectInput(inputId = "check1", label = "Choose", 
                  choices = c("choice A","choice B","choice C"), multiple = T),
      verbatimTextOutput(outputId = "res1"), 
      actionButton('submit', 'Done')
    )
  )
)
server <- function(input, output, session) {
  
  flag_lifecycle <- reactiveValues(val = "Yes")
  
  output$res1 <- renderPrint({
    input$check1
  })
  
  observeEvent(input$submit, {
    shinyjs::disable("check1")
  })
  
}
shinyApp(ui = ui, server = server)

CodePudding user response：

Use selectizeInput().

The function below adds 2 functionalities to your selectizeInput():

Ability to remove an already made choice.
Limit max number of items that can be selected.

# ----selectizeInput options---
selectizeOptions <- function (n = NULL) { # n is the max number of items
  if (is.null(n)) {
    list(
      plugins = list("remove_button")
    )
  }else {
    list(
      plugins = list("remove_button"), 
      maxItems = n
    )
  }
}

Here is an example:

library(shiny)

ui <- fluidPage(
  # ----selections here----
  selectizeInput(
    inputId = "thechoices",
    label = "Choose",
    choices = LETTERS,
    selected = "A", 
    multiple = TRUE,
    options = selectizeOptions(n = 4)
  )
)

server <- function(input, output, session) {
  
}

shinyApp(ui, server)