R shiny object scoping - r

Question

I'm trying to access an object(a<-get(obj1,envir=parent.environment())) residing in the calling environment from the called environment myf and I can't get it working. Error I'm getting is Object obj1 not found. I tried parent.frame()also. Any ideas?
library(shiny)
shinyApp(
ui = textOutput("test1"),
server = function(input, output) {
myf <- function(x) {
a <- get(obj1, envir = parent.environment())
return(paste0(x,a))
}
output$test1 <- renderText({
obj1 <- "testing"
a <- lapply(c("a","b","c"), myf)
return(paste(unlist(a), collapse = ","))
})
}
)
NOTE : I do NOT want to create obj1 using obj1<<- as it creates in Global Environment and is available for all sessions

Answer 1

The correct solution is that you have three problems: First of all, you need to quote "obj1" like this
get("obj1", envir = ...)
Secondly, parent.environment() is not a function. It doesn't exist.
Thirdly, you need to understand environment and calling frames a little bit to know how this works (it has nothing to do with Shiny). What you want to use is parent.frame(2) (being inside an lapply adds a layer)
So to modify your original code, this is the solution:
library(shiny)
shinyApp(
ui = textOutput("test1"),
server = function(input, output) {
myf <- function(x) {
a <- get("obj1", envir = parent.frame(2))
return(paste0(x,a))
}
output$test1 <- renderText({
obj1 <- "testing"
a <- lapply(c("a","b","c"), myf)
return(paste(unlist(a), collapse = ","))
})
}
)

Answer 2

I'm not sure why it doesn't work, but there' a simple workaround: explicitly pass obj1 to myf:
library(shiny)
shinyApp(
ui = textOutput("test1"),
server = function(input, output) {
## myf now takes two arguments, x and a:
myf <- function(x, a) {
return(paste0(x, a))
}
output$test1 <- renderText({
obj1 <- "testing"
## Now you can just pass obj1 as a second argument to myf
## without worrying about scoping:
a <- lapply(c("a","b","c"), myf, obj1)
return(paste(unlist(a), collapse = ","))
})
}
)