How do you pass parameters to a shiny app via URL

Question

In web browsers you pass parameters to a website like

www.mysite.com/?parameter=1

I have a shiny app and I would like to use the parameter passed in to the site in calculations as an input. So is it possible to do something like www.mysite.com/?parameter=1 and then use input!parameter?

Can you provide any sample code or links?

Thank you

Answer 1

You'd have to update the input yourself when the app initializes based on the URL. You would use the session$clientData$url_search variable to get the query parameters. Here's an example, you can easily expand this into your needs

library(shiny)  shinyApp(   ui = fluidPage(     textInput("text", "Text", "")   ),   server = function(input, output, session) {     observe({       query <- parseQueryString(session$clientData$url_search)       if (!is.null(query[['text']])) {         updateTextInput(session, "text", value = query[['text']])       }     })   } ) 

Answer 2

Building off of daattali, this takes any number of inputs and does the assigning of values for you for a few different types of inputs:

ui.R:

library(shiny)  shinyUI(fluidPage( textInput("symbol", "Symbol Entry", ""),  dateInput("date_start", h4("Start Date"), value = "2005-01-01" ,startview = "year"),  selectInput("period_select", label = h4("Frequency of Updates"),             c("Monthly" = 1,               "Quarterly" = 2,               "Weekly" = 3,               "Daily" = 4)),  sliderInput("smaLen", label = "SMA Len",min = 1, max = 200, value = 115),br(),  checkboxInput("usema", "Use MA", FALSE)  )) 

server.R:

shinyServer(function(input, output,session) { observe({  query <- parseQueryString(session$clientData$url_search)   for (i in 1:(length(reactiveValuesToList(input)))) {   nameval = names(reactiveValuesToList(input)[i])   valuetoupdate = query[[nameval]]    if (!is.null(query[[nameval]])) {     if (is.na(as.numeric(valuetoupdate))) {       updateTextInput(session, nameval, value = valuetoupdate)     }     else {       updateTextInput(session, nameval, value = as.numeric(valuetoupdate))     }   }   }   }) }) 

Example URL to test: 127.0.0.1:5767/?symbol=BBB,AAA,CCC,DDD&date_start=2005-01-02&period_select=2&smaLen=153&usema=1

Answer 3

Shiny App: How to Pass Multiple Tokens/Parameters through URL

The standard delimeter for tokens passed through url to shiny app is the & symbol.

Example shiny app code:

server <- function(input, output, session) {
  observe({
    query <- parseQueryString(session$clientData$url_search)
    if (!is.null(query[['paramA']])) {
        updateTextInput(session, "InputLabel_A", value = query[['paramA']])
    }
    if (!is.null(query[['paramB']])) {
        updateTextInput(session, "InputLabel_A", value = query[['paramB']])
    }
  })
  # ... R code that makes your app produce output ..
}

Coresponding URL example: http://localhost.com/?paramA=hello&?paramB=world

Reference: parseQueryString Docs