shinyWidgets updatePickerInput() server-side update (similar to updateSelectizeInput function)? - r

Question

Does anyone know of a way to use shinyWidgets::pickerInput() with a large number of choices, but speed up the rendering? (similar to server-side selectize using updateSelectizeInput())
What I'm ultimately trying to do: have a shinyWidgets pickerInput() with a large number of choices (~1M).
The problem: it takes a really long time for the app to load with that many choices.
I know that one workaround is to use the shiny::selectizeInput() UI element, because there is a neat way to do a server-side shiny::updateSelectInput(), which makes both the loading of the initial UI element and the subsequent update with a bunch of options run pretty quickly (as described in this article).
However, I really like the formatting options and flexibility that shinyWidgets::pickerInput() offers.
Examples:
This works and loads quickly, but uses shiny::selectizeInput() instead of shinyWidgets::pickerInput(), which I want to use.
library(shiny)
ui = shiny::fluidPage(
shiny::uiOutput(outputId = "ui_output")
)
server = function(input, output) {
output$ui_output = shiny::renderUI({
shiny::selectizeInput(
inputId = "select",
label = "Select:",
choices = NULL
)
})
shiny::observe({
shiny::updateSelectizeInput(
inputId = "select",
choices = 1:1000000,
selected = 1,
server = TRUE
)
})
}
shiny::shinyApp(ui, server)
When trying to do the same with shinyWidgets::pickerInput(), I tried both loading the choices directly into the UI initially:
server = function(input, output) {
output$ui_output = shiny::renderUI({
shinyWidgets::pickerInput(
inputId = "select",
label = "Select:",
choices = 1:1000000
)
})
}
And also trying to same logic that I used in the first example, which is to initially load the UI object with choices = NULL, and then have a shiny::observe() call that updates the UI element's choices (this works, but is really slow):
server = function(input, output) {
output$ui_output = shiny::renderUI({
shinyWidgets::pickerInput(
inputId = "select",
label = "Select:",
choices = NULL
)
})
shiny::observe({
shinyWidgets::updatePickerInput(
session = getDefaultReactiveDomain(),
inputId = "select",
choices = 1:1000000,
selected = 1
)
})
}