How to attach `tabPanel` to `menuSubItem`?

I have two data frames put in a single tabpanel appearing on a dashboardBody. Can someone help me attach this tabpanel to the menuSubItem titled "Inventory" appearing on a dashboardSidebar as given in the following script?

Also I need a help to create a space between the two data frames since they are located in a single tabpanel one over the other.

df1 = data.table(
    "Сolumn1"= as.character(),
    "Column2"= as.numeric())

df2 = data.table(
    "Сolumn1"= as.character(),
    "Column2"= as.numeric())


ui <- dashboardPage(
  dashboardHeader(title = "Assets"),
  dashboardSidebar(
    menuItem("Home", tabName = "home"),
    menuItem("Current assets", tabName = "CurrentAssets",
    menuSubItem("Inventory", tabName="inventory")
   )
  ),
  dashboardBody(
    tabsetPanel(
      tabPanel(tabName = "inventory",
        "df1",
        rHandsontableOutput("Table1")
        ),
    tabsetPanel(
      tabPanel(tabName = "inventory",
        "df2",
        rHandsontableOutput("Table2")
    )
      )
    )
  )
)


server <- function(input, output, session) {

    output$Table1 <- renderRHandsontable({
            rhandsontable(df1)
  })

    output$Table2 <- renderRHandsontable({
            rhandsontable(df2)
  })

    }

shinyApp(ui, server)

Solution

To connect or attach a tab with a menuItem or subMenuItem you have to use tabItems and tabItem instead of tabSetPanel and tabPanel. For the layout you could wrap each rHandsontable in column to use a column layout and to set the width or the number of columns (there are 12 at max) to use for this table.

library(shinydashboard)
library(shiny)
library(rhandsontable)

ui <- dashboardPage(
  dashboardHeader(title = "Assets"),
  dashboardSidebar(
    menuItem("Home", tabName = "home"),
    menuItem("Current assets",
      tabName = "CurrentAssets",
      menuSubItem("Inventory", tabName = "inventory")
    )
  ),
  dashboardBody(
    tabItems(
      tabItem(
        tabName = "inventory",
        column(
          width = 3,
          "df1",
          rHandsontableOutput("Table1")  
        ),
        column(
          width = 3,
          "df2",
          rHandsontableOutput("Table2")
        )
      )
    )
  )
)

server <- function(input, output, session) {
  output$Table1 <- renderRHandsontable({
    rhandsontable(df1)
  })

  output$Table2 <- renderRHandsontable({
    rhandsontable(df2)
  })
}

shinyApp(ui, server)