How do i include input widgets under menuSubItem in shiny dashboard sidebar?

Question

How is it possible to include a control widget under the menuSubItem in the sidebar of a shiny app?

This is my trial:

library(shiny)
library(shinyWidgets)
library(shinydashboard)

ui <- dashboardPage(
  
  ### Header -----
  
  dashboardHeader(title = "Example App"),
  
  ### Sidebar -----
  
  dashboardSidebar(
    
    sidebarMenu(
              
      menuItem(
        text = "A",
        tabName = "analytics",
        icon = icon("signal"),
        startExpanded = TRUE,
        
        menuSubItem(text = "a",
                    icon = NULL,
                    
                    pickerInput(
                      inputId = "Id086",
                      label = "Placeholder", 
                      choices = c("a", "b", "c", "d"),
                      options = list(
                        title = "This is a placeholder")
                    )
                    ),
        
        
        menuSubItem(text = "b",
                    icon = NULL)
        
        
      )
      
    )
    
  ),
  
  dashboardBody(
    
  )
  
)

## Server-function -----

server <- function(input, output) {
  
  
}

# Run the application 
shinyApp(ui = ui, server = server)

However, the desired input does not appear within the app. I managed it to include the input widget under any of the menu items but i failed to make it appear under menuSubItems.

Answer 1

menuSubItems are intended to navigate tabItems in the body - that is why they can't have child elements.

You can use nested menuItems to place additional inputs in the sidebar (please see the below example) which "behave" differently when childfull / childless.

When a menuItem is childfull it accepts the parameters expandedName and startExpanded.

When a menuItem is childless it accepts the parameters tabName and selected.

A menuSubItem is always childless.

library(shiny)
library(shinyWidgets)
library(shinydashboard)

ui <- dashboardPage(
  dashboardHeader(title = "Example App"),
  dashboardSidebar(sidebarMenu(
    menuItem(
      text = "A",
      # tabName = "analytics", # childfull menuItems ignore the tabName parameter they use expandedName instead
      icon = icon("signal"),
      startExpanded = TRUE,
      menuItem(
        text = "a",
        menuSubItem(
          text = "a1",
          tabName = "tab_a1",
          icon = NULL
        ),
        pickerInput(
          inputId = "Id086",
          label = "Placeholder",
          choices = c("a", "b", "c", "d"),
          options = list(title = "This is a placeholder")
        ),
        icon = NULL,
        startExpanded = TRUE
      ),
      menuSubItem(
        text = "b",
        tabName = "tab_b",
        icon = NULL
      )
    )
  )),
  dashboardBody(tabItems(
    tabItem(tabName = "tab_a1",
            h2("tab_a1 content")),
    tabItem(tabName = "tab_b",
            h2("tab_b content"))
  ))
)

server <- function(input, output) {
}

shinyApp(ui = ui, server = server)

Here you can find a related question.

However, personally I'd recommend using shinydashboardPlus's right sidebar for inputs and use the left sidebar only for navigation.