How can I adress the parent menuItem in a nested dashboardSidebar - r

Question

In the example below, there are two menuItems (1 and 2) and a menuSubItem (2.1) thats nested within menuItem 2. Each menuItem has a corresponding tabItem with a box, where the boxtitle is the name of the menuItem. If i run this app "Menu 1" is initally selected and shows the box called "1". If i than click on "Menu 2" the menuSubItem expands, but the body does not change at all.
I don't think that this is the normal behaviour, is there a way to fix this?
And a second question. If I have selected "Menu 2.1" and click on "Menu 1" why does the nested menuItem do not collapse again?
library(shiny)
library(shinydashboard)
ui <- dashboardPage(
dashboardHeader(disable=TRUE),
dashboardSidebar(
sidebarMenu(
menuItem(
"Menu 1",
tabName="menu1"
),
menuItem(
"Menu 2",
tabName = "menu2",
menuSubItem(
"Menu 2.1",
tabName = "menu2_1"
)
)
)
),
dashboardBody(
tabItems(
tabItem(tabName="menu1",
box("1")
),
tabItem(tabName="menu2",
box("2")
),
tabItem(tabName="menu2_1",
box("2.1")
)
)
)
)
server <- function(input, output) {
}
shinyApp(ui = ui, server = server)

Answer 1

The behaviour you see is normal, see here
Childless menuItem()s/menuSubItem()s must be given a tabName argument
Childfull” menuItem()s cannot have a tabName or a selected argument
(or rather, they can, but this will be completely ignored by Shiny).
Instead, at most, one of them can take a startExpanded = TRUE, which
tells Shiny to start out with that menuItem() expanded, i.e. revealing
all its children
You can access the expanded tab with my code below, so you can create behavior based on that, but I do not think it is possible to display a page when clicking a menuItem that has children.
Hope this helps!
library(shiny)
library(shinydashboard)
ui <- dashboardPage(
dashboardHeader(disable=TRUE),
dashboardSidebar(
sidebarMenu(
menuItem(
"Menu 1",
tabName="menu1"
),
menuItem(
"Menu 2",
expandedName = "menu2",
menuItem(
"Menu 2.1",
tabName = "menu2_1"
)
)
),
textOutput('selectedmenu')
),
dashboardBody(
tabItems(
tabItem(tabName="menu1",
box("1")
),
tabItem(tabName="menu2",
box("2")
),
tabItem(tabName="menu2_1",
box("2.1")
)
)
)
)
server <- function(input, output) {
output$selectedmenu <- renderText({
print(input$sidebarItemExpanded)
})
}
shinyApp(ui = ui, server = server)
Change first tab when menu 2 is expanded, request from comment:
library(shiny)
library(shinydashboard)
ui <- dashboardPage(
dashboardHeader(disable=TRUE),
dashboardSidebar(
sidebarMenu(id="mysidebar",
menuItem(
"Menu 1",
tabName="menu1"
),
menuItem(
"Menu 2",
expandedName = "menu2",
menuItem(
"Menu 2.1",
tabName = "menu2_1"
)
)
)
),
dashboardBody(
tabItems(
tabItem(tabName="menu1",
box("1")
),
tabItem(tabName="menu2",
box("2")
),
tabItem(tabName="menu2_1",
box("2.1")
)
)
)
)
server <- function(input, output,session) {
observeEvent(input$sidebarItemExpanded, {
updateTabItems(session,"mysidebar","menu2_1")
})
}
shinyApp(ui = ui, server = server)