Pass objects to shiny app and launch with runApp - r

Question

I am creating a package that contains a few interactive shiny apps. The purpose of these apps is to facilitate GUI exploration of in-memory objects. For example, I have an object consisting of discretized variables I would like to pass to the shiny app and then make adjustments via the GUI interface.
However, I am running into trouble when trying to access this in-memory object from the Shiny App.
Here is the relevant code:
First, I am wrapping the shinyServer function in another function. My thought here is to give the shiny server access to the passed object.
#' #export
appServer <- function(bins) {
su <- summary(bins)
shinyServer(function(input, output) {
## values that should trigger updates when changed
values <- reactiveValues(summary=su, i=1, bins=bins)
# excluded rest of body for brevity ...
}
In this function, I create a shinyApp object and pass in the ui (in another file) and the result of the appServer function defined above.
makeApp <- function(bins) {
shiny::shinyApp(
ui = appUI,
server = appServer(bins))
}
The preceding functions are called in this function that wraps the call to runApp and takes an argument from the user.
#' #export
adjust <- function(bins) {
## access data from the app?
app <- makeApp(bins)
shiny::runApp(app)
}
How can I pass an in-memory object to a shinyApp that is imported from another package?
When I execute the above code, I receive the following error:
ERROR: path[1]="C:\Users\myusername\AppData\Local\Temp\RtmpWMpvHT\widgetbinding23e8333e5298": The system cannot find the path specified

Answer 1

In the example below I demonstrate how you can pass an object x from the global environment or from any other environment to the shiny app and change its value. I'm not sure if this answers your question. It maybe prove useful anyway :)
library(shiny)
x <- 5
x
deparse(substitute(x)) # is going to do the trick
fun <- function(obj) {
# get the name of the passed object
object_to_change <- deparse(substitute(obj))
# get the object from a given environment
val <- get(object_to_change, envir = .GlobalEnv)
# ?environment
# Save the object as a reactive value
values <- reactiveValues(x = val)
# Now define the app that is going to change the value of x
ui <- shinyUI(fluidPage(
br(),
actionButton("quit", "Apply changes and quit"),
textInput("new", "", value = NULL, placeholder = "Set new value of x"),
textOutput("out")
))
server <- function(input, output) {
output$out <- renderPrint({
values$x
})
# change the value of x
observe({
req(input$new)
values$x <- as.numeric(input$new)
})
# Apply changes and quit
observe({
if (input$quit == 1) {
assign(x = object_to_change, value = values$x, envir = .GlobalEnv)
stopApp()
}
})
}
# Run the app
shiny::shinyApp(ui, server)
}
fun(x)
# Check the new value of x in the .GlobalEnv
x