如何知道应用程序是在本地还是在服务器上运行？ (R 闪亮)

Question

I test my app on my laptop, and then deploy it to shinyapps server. Before deploying, I need to remove the statement setting the path, eg,

setwd('/Users/MrY/OneDrive/Data')

Is there a way the code can find out if it's running locally or on server, so that it will be like:

if (isLocal()) {
       setwd('/Users/MrY/OneDrive/Data')
}

---

A trivial sample code (it will fail on server if setwd isn't removed):

server.R

library(shiny)

setwd('/Users/Yuji/OneDrive/Data/TownState')  

data = 'data1.csv'  # to test, using an empty .csv file

shinyServer(function(input, output) {


}) 

ui.R

library(shiny)

shinyUI(pageWithSidebar(
    headerPanel("Click the button"),

    sidebarPanel(
        actionButton("goButton", "Go!")
    ),
    mainPanel(

    )
))

Answer 1

The standard way to do this in Shiny is with: Sys.getenv('SHINY_PORT') . You could write something like:

is_local <- Sys.getenv('SHINY_PORT') == ""

Answer 2

EDIT 2020: There still is no official way to do this, but I would opt for Yihui's method of is_local <- Sys.getenv('SHINY_PORT') == ""

---

I don't know if this is the proper way or not, but you could look at the host using session$clientData$url_hostname . When you run it locally, unless you specifically change the host, it will be 127.0.0.1 and I'm guessing on shinyapps it'll be something like shinyapps.io . Sample code

runApp(shinyApp(
  ui = fluidPage(
  ),
  server = function(input, output, session) {
    observe({
      if (session$clientData$url_hostname == "127.0.0.1") {
        setwd(...)
      }
    })
  }
))

Something of that sort should work, though I can't vouch for whether or not it's the best solution

Answer 3

You could retrieve the host name and query that. The computers should have different host names.

    library(R.utils)
    hname <- System$getHostname()

yields

           nodename 
"mikes-air-3.wisedom.local"