I would like to know if I can use interchangeably getDefaultReactiveDomain() with session object as a parameter in the server function. In other words: is getDefaultReactiveDomain() a function which returns R6 object and session is just this R6 object which is returned by getDefaultReactiveDomain()?
Let's say, I would like to write a function to reload a web page and I want it to work even if user doesn't include session parameter in server function:
reload <- function() {
getDefaultReactiveDomain()$reload()
}
Can I do it safely? I think that I do not see generally usage of getDefaultReactiveDomain()$ on Internet (speaking broadly), but session$, so I'm afraid it could be not so easy as I think.
MRE:
getDefaultReactiveDomain
library(shiny)
library(magrittr)
reload <- function() {
getDefaultReactiveDomain()$reload()
}
ui <- fluidPage(
actionButton("reload", "Reload")
)
server <- function(input, output) {
observe({
reload()
}) %>%
bindEvent(input$reload)
}
shinyApp(ui, server)
session
library(shiny)
library(magrittr)
ui <- fluidPage(
actionButton("reload", "Reload")
)
server <- function(input, output, session) {
observe({
session$reload()
}) %>%
bindEvent(input$reload)
}
shinyApp(ui, server)
I would like to add that in the shiny source code I see returned value from getDefaultReactiveDomain() as a default value passed to the session parameter, for example in this function:
shiny::updateActionButton
#> function (session = getDefaultReactiveDomain(), inputId, label = NULL,
#> icon = NULL)
#> {
#> validate_session_object(session)
#> if (!is.null(icon))
#> icon <- as.character(validateIcon(icon))
#> message <- dropNulls(list(label = label, icon = icon))
#> session$sendInputMessage(inputId, message)
#> }
#> <bytecode: 0x000000001dbdc2a0>
#> <environment: namespace:shiny>
So I could be safe using just getDefaultReactiveDomain() in my function (and using it internally, not as a default value for parameter, which user can change). However, if that's true, why then in update* functions from shiny other value can be passed to session parameter?
