Shiny Dashboard: Render multiple menu items and output dynamic content to each - r

Question

I need to render various menu sub-items based on some reactive data values. For each sub-item, I also need to associate linked output. I tried to link with tabName, but not sure what went wrong.
Below is an example. The desired output will be one box for each menu item/sub-item.
## This code snippet doesn't do what I need ----
shinyApp(
ui = dashboardPage(
dashboardHeader(),
dashboardSidebar(
sidebarMenu(
menuItemOutput("dynamic_menu"),
menuItem("Menu2", tabName = "menu2")
)
),
dashboardBody(
tabItems(
uiOutput("menu1_content"),
tabItem(tabName = "menu2", box("I am menu2"))
)
),
title = "Example"
),
server = function(input, output) {
output$dynamic_menu <- renderMenu({
submenu_list <- lapply(letters[1:5], function(x) {
menuSubItem(x, tabName = paste0("menu1-", x))
})
menuItem(
text = "Menu1",
startExpanded = TRUE,
do.call(tagList, submenu_list)
)
})
output$menu1_content <- renderUI({
content_list <- lapply(letters[1:5], function(x) {
tabItem(
tabName = paste0("menu1-", x),
box(x)
)
})
do.call(tagList, content_list)
})
}
)
## This code snippet does what I need ----
shinyApp(
ui = dashboardPage(
dashboardHeader(),
dashboardSidebar(
sidebarMenu(
menuItem(
"Menu1", startExpanded = TRUE,
menuSubItem("a", tabName = "menu1-a"),
menuSubItem("b", tabName = "menu1-b"),
menuSubItem("c", tabName = "menu1-c"),
menuSubItem("d", tabName = "menu1-d"),
menuSubItem("e", tabName = "menu1-e")
),
menuItem("Menu2", tabName = "menu2")
)
),
dashboardBody(
tabItems(
tabItem(tabName = "menu1-a", box("a")),
tabItem(tabName = "menu1-b", box("b")),
tabItem(tabName = "menu1-c", box("c")),
tabItem(tabName = "menu1-d", box("d")),
tabItem(tabName = "menu1-e", box("e")),
tabItem(tabName = "menu2", box("I am menu2"))
),
title = "Example"
)
),
server = function(input, output) {}
)

Answer 1

Answering my own question, but feel free to jump in if you have something more elegant.
I think my initial understanding of shiny dashboard is wrong, causing the app structure to be invalid.
The trick here is to add id to the sidebarMenu, so that page focus could be tracked and parsed later. Then each of the render function will listen on the input and render associated content.
shinyApp(
ui = dashboardPage(
dashboardHeader(),
dashboardSidebar(
sidebarMenu(
id = "sidebar_menu",
menuItemOutput("dynamic_menu"),
menuItem("Menu2", tabName = "menu2")
)
),
dashboardBody(
uiOutput("menu1_content"),
uiOutput("menu2_content")
),
title = "Example"
),
server = function(input, output, session) {
output$dynamic_menu <- renderMenu({
menu_list <- lapply(letters[1:5], function(x) {
menuSubItem(x, tabName = paste0("menu1-", x))
})
menuItem(
text = "Menu1",
startExpanded = TRUE,
do.call(tagList, menu_list)
)
})
output$menu1_content <- renderUI({
sidebar_menu <- tstrsplit(input$sidebar_menu, "-")
if (sidebar_menu[[1]] == "menu1") box(sidebar_menu[[2]])
})
output$menu2_content <- renderUI({
sidebar_menu <- tstrsplit(input$sidebar_menu, "-")
if (sidebar_menu[[1]] == "menu2") box("I am menu2")
})
}
)