How to populate dropdown with reactive values

[wvictor14]

Hi, I want to initialize my app with no choices in Dropdown.shinyInput and then populate the choices from a reactive input on the server side. For example, I am able to do this with Combox.shinyInput by setting options and value parameters to NULL. But if I set these same parameters to NULL in Dropdown.shinyInput, the app doesn't load.

Is this possible, are there workarounds?

library(shiny)
library(shiny.fluent)

# app  doesn't load
shinyApp(
  ui = fluentPage(
    Dropdown.shinyInput("metro", options = options)
  ),
  server = function(input, output, session) {}
)

# options set to NULL works for ComboBox
shinyApp(
  ui = fluentPage(
    ComboBox.shinyInput("metro", options = NULL, values = NULL)
  ),
  server = function(input, output, session) {}
)