R shiny conditionalPanel output value

Question

There are many questions about conditionalPanel in R shiny, but I still don't understand how I can use values created by server.R for conditionalPanel. Here is what I would like to do: I have a URL like http://some-url.com/php/session_check.php?sid=session_id. When the session_id starts with a 0, like http://some-url.com/php/session_check.php?sid=00221245 a string with a username is returned (e.g. 'testuser'). When the session_id starts with any other number but 0, like http://some-url.com/php/session_check.php?sid=10221245 a 0 is returned. Now I would like to hide a panel, depending on whether the a 0 or a username is returned. Therefore I try to do something like this:

conditionalPanel(
 condition="output.disable_ui!=0"

I know that this is the wrong, but I don't really understand how the condition argument works for outputs, as the same would work if I would do this for any input from ui.R.

Here is my sample code:

server.R

library(shiny)
library(raster)
library(rgdal)

shinyServer(function(input, output, clientData) {

  output$disable_ui<-reactive({
    query<-parseQueryString(clientData$url_search)
    url_path<-paste(sep="","http://some-url.com/php/session_check.php?sid=",query, collapse="")
    read.table(url_path)
  })

  data <- reactive({  
    inFile <- input$example_layer 

    if (is.null(inFile)) 
      return(NULL)
    raster.file<- raster(inFile$datapath) 
  })

  output$raster.plot <- renderPrint({
    "Nothing to see here"
  })
})

ui.R

library(shiny)

shinyUI(pageWithSidebar(

  headerPanel("test"),

  sidebarPanel(
    conditionalPanel(
      condition="output.disable_ui!=0",

    #File Upload
    fileInput('example_layer', 'Choose Raster Layer (ASCII)', multiple=FALSE, accept='asc')

  )),

  mainPanel(
    verbatimTextOutput("raster.plot")
  )
))

If this would work all that would happen is that a file upload button would be shown (or not) depending on the url. No file will be uploaded. The user would be asked to search for and select a file after they press the button. Is that what you want? — Vincent
– Vincent, Commented Feb 6, 2014 at 20:29
It is not really about the file upload button. All I want is, that the sidebar panel or even all panels are not displayed when the url gives back a '0' and all panel are displayed when the url returns some 'username'. — viktor_r
– viktor_r, Commented Feb 7, 2014 at 8:50

Stéphane Laurent · Accepted Answer · 2014-02-06 22:52:05Z

18

@Julien Navarre is right: the output must be rendered. Except if you set its option suspendWhenHidden to FALSE:

  output$disable_ui<-reactive({
    query<-parseQueryString(clientData$url_search)
    url_path<-paste(sep="","http://some-url.com/php/session_check.php?sid=",query, collapse="")
    read.table(url_path)
  })
  outputOptions(output, 'disable_ui', suspendWhenHidden=FALSE)

answered Feb 6, 2014 at 22:52

Stéphane Laurent

85.3k18 gold badges140 silver badges261 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

viktor_r Over a year ago

can describe this in detail? What does suspendWhenHidden do? I just copied the line in my code and it didn't work. But it sounds like I really interesting solution, I would like to understand.Thanks

Stéphane Laurent Over a year ago

@user2524906 I don't know technical details but concretely if it is set to TRUE then the output is "detected" only when it is rendered. This is the cleanest solution. Other example here: stackoverflow.com/questions/19686581/…

micstr · Accepted Answer · 2020-07-07 08:56:04Z

13

I think that the output must be rendered in the UI if you want to use it after in the condition of a conditionalPanel.

With you example, the HTML for the conditional panel will look like something like this :

<div data-display-if="output.disable_ui!=0">

If no elements in your page (created as outputs in the server side) have the id "disable_ui" then the condition "output.disable_ui!=0" is always TRUE, and the conditional panel always displayed.

A simple example :

shiny::runApp(list( 
  ui = pageWithSidebar(
    
    headerPanel("test"),
    
    sidebarPanel(
      selectInput(
        "var", "Var",
        0:9)),
    
    mainPanel(
      verbatimTextOutput("id"),
      conditionalPanel(
        condition="output.id!=0",
        h4('Visible')
      )
    )
  ),
  server = function(input, output) {
    
    output$id<-reactive({input$var})
    
  }
))

If you select a number different of 0 the conditional panel will be displayed. Now, comment the line verbatimTextOutput("id"),, there is no more element with the id "id" in the page and then the condition of the conditional panel <div data-display-if="output.id!=0"> can't be FALSE.

edited Jul 7, 2020 at 8:56

micstr

5,2568 gold badges52 silver badges80 bronze badges

answered Feb 6, 2014 at 22:43

Julien Navarre

7,8603 gold badges46 silver badges73 bronze badges

1 Comment

viktor_r Over a year ago

Thanks @Julien Navarre, to render the output did the trick for me.

Yunnosch · Accepted Answer · 2018-08-07 06:45:42Z

10

This is the real answer to this question: Use this inside of your server function:

outputOptions(output, "outputId", suspendWhenHidden = FALSE)

You will then be able to use the output.item in your conditionalPanel.

Answer from here: https://github.com/daattali/advanced-shiny/blob/master/server-to-ui-variable/app.R

And here: https://github.com/rstudio/shiny/issues/1318

edited Aug 7, 2018 at 6:45

Yunnosch

26.8k9 gold badges46 silver badges66 bronze badges

answered Aug 7, 2018 at 6:39

clancy

3021 gold badge4 silver badges11 bronze badges

3 Comments

Filnor Over a year ago

A link to a solution is welcome, but please ensure your answer is useful without it: add context around the link so your fellow users will have some idea what it is and why it’s there, then quote the most relevant part of the page you're linking to in case the target page is unavailable. Answers that are little more than a link may be deleted.

clancy Over a year ago

This is no longer a link only answer.

Jeff Over a year ago

Thanks a lot, this is exactly the issue I have. I'm glad to find this answer!

Collectives™ on Stack Overflow

R shiny conditionalPanel output value

3 Answers 3

2 Comments

1 Comment

3 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

2 Comments

1 Comment

3 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related