Accessing parent namespace inside a Shiny Module - r

Question

I'm trying to updateSelectInput on a selectInput from the parent namespace inside a sub-module. In the module function, I'm inside the namespace as far as I understand, and therefore I can't access and update the selectInput from the parent namespace. How can I solve this?
library(shiny)
library(shinydashboard)
moduleUI <- function(id) {
ns <- NS(id)
box(
title=actionLink(ns("link"),"This is a link"),
plotOutput(ns("plot"))
)
}
module <- function(input, output,session,number) {
output$plot <- renderPlot({
plot(number)
})
observeEvent(input$link,{
print(paste0("Number is: ",number))
updateSelectInput(session,"selectInput",selected=number) #Doesn't work
})
}
ui <-
dashboardPage(
dashboardHeader(title="Title"),
dashboardSidebar(
selectInput("selectInput","Choose one option",choices=seq(1,10),selected=1)
),
dashboardBody(
moduleUI("5"),
moduleUI("10")
)
)
server <- function(session,input, output) {
callModule(module=module,id="5",5)
callModule(module=module,id="10",10)
}
shinyApp(ui = ui, server = server)

Answer 1

Took me a while, but I found a way to get the sub-module to update the super-module.
Shiny is designed so that access to other modules must be done via module arguments or returned values. We can not pass the widget ID between modules, but we can pass the session information of the parent.
library(shiny)
moduleUI <- function(id) {
ns <- NS(id)
uiOutput(ns("my_link"))
}
module <- function(input, output, session, number, parent) {
output$my_link <- renderUI({
actionLink(session$ns("link"), paste0("This is a link to ", number))
})
observeEvent(input$link,{
updateSelectInput(session = parent,"selectInput",selected = number) ### use parent session
})
}
ui <- fluidPage(
selectInput("selectInput","Choose one option",choices=seq(1,10),selected=1),
moduleUI("5"),
moduleUI("10")
)
server <- function(session,input, output) {
callModule(module = module, id = "5", 5, parent = session) ### pass session information
callModule(module = module, id = "10", 10, parent = session) ### pass session information
}
shinyApp(ui = ui, server = server)
In particular note that:
we pass the current session information when the sub-module is called
we use the parent session when updating the input selector

Answer 2

I think the ideal would be to get the sub-module to observe and update the super-module. However, I can only offer a solution in line with my comment above: having one observer per sub-module in the super-module. This will rapidly get cumbersome if you have many sub-modules.
library(shiny)
library(shinydashboard)
moduleUI <- function(id) {
ns <- NS(id)
box(
title=actionLink(ns("link"),"This is a link"),
plotOutput(ns("plot"))
)
}
module <- function(input, output,session,number) {
current = reactiveValues()
current$return_value = 0
returnvalue <- reactive(current$return_value)
output$plot <- renderPlot({
plot(number)
})
observeEvent(input$link,{
print(paste0("Number is: ",number))
current$return_value = current$return_value + 1
})
return(list(rv = returnvalue, num = number))
}
ui <-
dashboardPage(
dashboardHeader(title="Title"),
dashboardSidebar(
selectInput("inputID","Choose one option",choices=seq(1,10),selected=1),
actionButton("button","Knap")
),
dashboardBody(
moduleUI("5"),
moduleUI("10")
)
)
server <- function(session,input, output) {
val1 <- callModule(module=module,id="5",5)
val2 <- callModule(module=module,id="10",10)
observeEvent(val1$rv(),{
updateSelectInput(session,inputId="inputID",selected=val1$num)
})
observeEvent(val2$rv(),{
updateSelectInput(session,inputId="inputID",selected=val2$num)
})
}
shinyApp(ui = ui, server = server)
Key changes from Tobias's question:
sub-modules have different names
separate observer for each sub-module
sub-module contains a return_value that gets updated every time the link is clicked. This ensures the observer in the super-module has a change to observe.
sub-module returns a list with two values: return_value as described above, and the value to update the UI with.