CODEWITHSUNDEEP
rshiny
msaltieri
msaltieri

Reputation: 172

Disable a selectInput in R Shiny when not required

I am building a shiny web page with a form made up of two selectInput: the first one - static - in the ui section and the second one - dynamic - in the server section. A simplification of the real issue is shown below.

require(shiny)

ui <- fluidPage(

    # The static input
    selectInput(inputId = 'static',
                label = 'Make a choice',
                choices = c('A', 'B', 'C'),
                selectize = FALSE),

    # The dynamic input
    uiOutput(outputId = 'dynamicInput'),

    # The output
    hr(),
    strong('This is a check for the output:'),
    textOutput(outputId = 'check')

)

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

    # The dynamic input definition
    output$dynamicInput <- renderUI({

        # This input exists if the `static`
        # one is equal to `A` only
        if (input$static == 'A') {
            selectInput(inputId = 'dynamic',
                        label = 'Choose a subset for `A`',
                        choices = c('A1', 'A2', 'A3'),
                        selectize = FALSE)
        } else {
            return(NULL)
        }

   })

   # The example output
   output$check <- renderText({

       paste(input$static, input$dynamic)

   })

}

shinyApp(ui, server)

In the real case I have to launch a query on a database based on the static input and, eventually, the dynamic one (if exists).

When testing the app I correctly got the dynamic selectInput at the first round and I am able to select - lets' say - the A2 option. Then, if I choose B in the static selectInput, the dynamic input is not responsive and still shows the previous selection instead of showing NULL.

How can I force the dynamic selectInput to reset if the static one is not equal to A? Do I have to manually hide it using some artifice such as Dean Attali's shinyjs?

Upvotes: 3

Views: 5372

Answers (1)

dvarelas
dvarelas

Reputation: 988

Try this one. It's a combination of using reactive values and an observe.

require(shiny)

ui <- fluidPage(

  # The static input
  selectInput(inputId = 'static',
              label = 'Make a choice',
              choices = c('A', 'B', 'C'),
              selectize = FALSE),

  # The dynamic input
  uiOutput(outputId = 'dynamicInput'),

  # The output
  hr(),
  strong('This is a check for the output:'),
  textOutput(outputId = 'check')

)

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

  ## list to store reactive values
  values <- reactiveValues()


  # The dynamic input definition
  output$dynamicInput <- renderUI({

    # This input exists if the `static`
    # one is equal to `A` only
    if (input$static == 'A') {
      selectInput(inputId = 'dynamic',
                  label = 'Choose a subset for `A`',
                  choices = c('A1', 'A2', 'A3'),
                  selectize = FALSE)
    } else {
      return(NULL)
    }

  })

  ## this bit fixes the issue
  observe({
    if (input$static == "A") {
      values$dyn <- input$dynamic
    } else {
      values$dyn <- NULL
    }
  })

  # The example output
  output$check <- renderText({

    paste(input$static, values$dyn)

  })

}

shinyApp(ui, server)

Upvotes: 11

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