Shiny dashboard preselect menuSubItem when clicking menuItem - r

Question

When clicking on a menu item in the side bar I would like it to not only expand and show the menu sub items but also preselect the first one and show the corresponding tab item UI.
I know it is possible to define one item as selected and it will show when I start the app. To me this is confusing behaviour because the corresponding menu item does not appear as "selected" in the sidebar. My requirement goes further anyway since I want to preselect a menu sub item every time I click on a menu item.
library(shinydashboard)
library(shiny)
ui <- dashboardPage(
dashboardHeader(),
dashboardSidebar(
sidebarMenu(
menuItem("Table1" , tabname = "my_table1", icon = icon("table"),startExpanded = F,
menuSubItem("sub menu1",tabName = "subMenu1"),
menuSubItem("sub menu2",tabName = "subMenu2")
),
menuItem("Table2" , tabname = "my_table2", icon = icon("table"),startExpanded = F,
menuSubItem("sub menu3",tabName = "subMenu3"),
menuSubItem("sub menu4",tabName = "subMenu4", selected = T)
)
)),
dashboardBody(
tabItems(
tabItem(tabName = "my_table1",
h2("First Table")
),
tabItem(tabName = "my_table2",
h2("Second Table")
),
tabItem(tabName = "subMenu1",
h2("First tab")
),
tabItem(tabName = "subMenu2",
h2("Second tab")
),
tabItem(tabName = "subMenu3",
h2("Third tab")
),
tabItem(tabName = "subMenu4",
h2("Fourth tab")
)
)))
server <- function(input, output) {
}
shinyApp(ui, server)

Answer 1

Your sidebarMenu needs an id and your server function needs the session argument, so you can use:
updateTabItems(session, inputId="sidebarID", selected="subMenu1")
Please check the following:
library(shinydashboard)
library(shiny)
ui <- dashboardPage(
dashboardHeader(),
dashboardSidebar(
sidebarMenu(
id = "sidebarID",
menuItem("Table1" , tabname = "my_table1", icon = icon("table"), startExpanded = TRUE,
menuSubItem("sub menu1",tabName = "subMenu1", selected = TRUE),
menuSubItem("sub menu2",tabName = "subMenu2")
),
menuItem("Table2" , tabname = "my_table2", icon = icon("table"), startExpanded = FALSE,
menuSubItem("sub menu3",tabName = "subMenu3"),
menuSubItem("sub menu4",tabName = "subMenu4")
)
)),
dashboardBody(
tabItems(
tabItem(tabName = "my_table1",
h2("First Table")
),
tabItem(tabName = "my_table2",
h2("Second Table")
),
tabItem(tabName = "subMenu1",
h2("First tab")
),
tabItem(tabName = "subMenu2",
h2("Second tab")
),
tabItem(tabName = "subMenu3",
h2("Third tab")
),
tabItem(tabName = "subMenu4",
h2("Fourth tab")
)
)))
server <- function(input, output, session) {
observeEvent(input$sidebarItemExpanded, {
cat(paste("menuItem() currently expanded:", input$sidebarItemExpanded, "\n"))
if(input$sidebarItemExpanded == "Table1"){
updateTabItems(session, inputId="sidebarID", selected="subMenu1")
} else if(input$sidebarItemExpanded == "Table2"){
updateTabItems(session, inputId="sidebarID", selected="subMenu3")
}
})
observe({
cat(paste("tabItem() currently selected:", input$sidebarID, "\n"))
})
}
shinyApp(ui, server)
Furthermore please see the related docs.