Updating a selectInput located in another module

[MatthieuL]

Hello everyone,

I have built a Shiny module that is aimed at handling selectInput with a large number of options. This small shiny module simply adds two buttons (a "Select all" button and a "Unselect all" button) below the selectInput widget.

Now, I have set up a small application where I used my Shiny module and defined two SelectizeInputs. I would like to dynamically update the choices of the first SelectizeInput (x) based on the value selected in the second SelectizeInput (y).

Here is a minimal code to reproduce the issue:

library(shiny)
library(tidyverse)


# Dummy dataframe
df <- tibble(x=1:10, y=rep(LETTERS[1:2], 5))

# the UI part of the module
customSelectUI <- function(id, label, choices, selected=NULL, placeholder=NULL, maxItems=NULL, plugins=list("remove_button")){
  ns <- NS(id)
  tagList(
    selectizeInput(
      ns("myselect"),
      label=label,
      choices=choices,
      selected=selected,
      multiple=TRUE,
      options=list(
        placeholder=placeholder,
        plugins=plugins,
        maxItems=maxItems
      )
    ),
    tags$div(
      style="display:inline-block; margin-bottom:20px;",
      actionButton(
        ns("selectAll"),
        "Sélectionner tout",
        class="btn-sm"
      ),
      actionButton(
        ns("unselectAll"),
        "Désélectionner tout",
        class="btn-sm"
      ) 
    )
  )
}

# the server part of the module
customSelectServer <- function(id, choices){
  moduleServer(
    id,
    function(input, output, session){
      observeEvent(
        input$selectAll,
        {
          updateSelectizeInput(
            session=getDefaultReactiveDomain(),
            inputId="myselect",
            choices=choices,
            selected=choices
          )
        }
      )
      observeEvent(
        input$unselectAll,
        {
          updateSelectizeInput(
            session=getDefaultReactiveDomain(),
            inputId="myselect",
            choices=choices,
            selected=NULL
          )
        }
      )
      
      return(
        reactive(
          {
            input$select
          }
        )
        
      )
    }
  )
}

# Choices for the select
x_choices <- distinct(df, x)%>%pull()
y_choices <- distinct(df, y)%>%pull()

# Main UI
ui <- fluidPage(
  fluidRow(
    customSelectUI("x", "Choose a value of x", x_choices),
    customSelectUI("y", "Choose a value of y", y_choices)
  )
)

# Main server function
server <- function(input, output){
  x <- customSelectServer("x", x_choices)
  y <- customSelectServer("y", y_choices)
  
  # Update the choices of X selectInput based on selection in Y
  filtered_x <- reactive({
    df %>% filter(y %in% y()) %>% distinct(x) %>% pull()
  })
  observeEvent(
    filtered_x,
    {
      updateSelectizeInput(
        inputId="x-myselect",
        choices=filtered_x()
      )
    }
  )
  
}

shinyApp(ui, server)

It does not work as expected. For instance, if the user select y==A, the possible values for x should be 1, 3, 5 etc.

Could anyone help ?

Thanks in advance !