Redirect in Shiny app

Question

I'm trying to make my Shiny app to redirect the user to another page. I'm using httr to send GET requests and see if the user is logged in. If he's not, I want to redirect him to another link.

Can I do that using R / Shiny only, or do I need some extra libraries?

sample:

library(httr)
library(shiny)
shinyServer(function(input, output) {
rv <- reactiveValues()
rv$mytoken = session$request$token

observeEvent(input$button1, {
  rv$a <- GET("my.url:3405/authtoken", 
              add_headers(
                .headers = c("token" = rv$mytoken)
              ))
  if (rv$a$status_code == 200) {
  } else {
    # redirect magic
  }
})
}

shinyUI(fluidPage(
  actionButton(button1, "btn")
))

Yuji

Can you provide sample code with username and password? – Skijoring

It's working in a different way: i have auth token in the session$request environment, and i check with GET if it's the same on the server. So I redirect user based on status code I'm getting in response. I will provide some code if needed – Yuji

You can still provide sample app without it, so when false then redirect – Skijoring

Is an example sufficient? – Yuji

Answer 1

Here this will navigate you to google if not true

library(shiny)

jscode <- "Shiny.addCustomMessageHandler('mymessage', function(message) {window.location = 'http://www.google.com';});"

ui <- fluidPage(
  tags$head(tags$script(jscode)),     
  checkboxInput("Redirect","Redirect",value = T)
)

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

  observeEvent(input$Redirect,{
    if(!input$Redirect){
      session$sendCustomMessage("mymessage", "mymessage")
    }
  })
}

shinyApp(ui,server)

Skijoring

As usual, you make it work :)The thing I was looking for, thank you! It seems though that you 'force' it to redirect the user. Doesn't shiny support this behaviour by default? – Yuji

Its easy to do within the ui where you can bind buttons and links but you need to send it back the redirect from server and theshiny team added the sendCustomMessage which is very useful. So just go through it, you will pick it up quite fast – Skijoring

have a look at paste – Skijoring

Yeah yeah my bad, i'll handle it now. Thanks again. – Yuji

Hi, I don't know if I should create new question - if my app is inside an iframe - it seems that it redirects only inside it, and not the whole webpage. Unfortunately, I can't produce any examples here. Do you think by chance there is a way to redirect the whole page to another url, using only shiny? – Yuji

There is an example how to capture click event within an iframe by John Harrison, have a look at that and study it, then you will be able to apply to your case. #46094896 – Skijoring

I just used window.top.location.href instead of window.location and it worked fine. Peace! – Yuji

What if I need to include some reactive value in the url? – Vedis

Is there no way to do this without JavaScript? Why can't the server side return a 302 response? Also what happens if JavaScript is disabled on client browser in this example? – Mascot

Answer 2

Just to update. There is also an easier way...

shinyjs::runjs(paste0('window.location.href = "...";'))

Don't forget useShinyjs() in UI.

Ovi

Note your address must begin with https:// – Marigraph