How do I update filter values based on previous filter when using shiny modules

[ML_Rookie_2021]

Hello, I'm creating a shiny app and trying to figure out how to update filters based on previous filters selection when using a shiny module.

In the module, the default, shows all countries and first purchase cohorts. I want the Customer ID picker input to automatically filter, based on what Country and First Purchase Cohort are selected.

Please see reprex below. Note that the modules are in a separate script and being sourced in the main shiny app -

# Libraries
library(tidyverse)
library(shiny)
# ******************************************************************************
# Sample Data
df <- tibble(
    data_1 = c(1758, 0, 0, 0, 0, 0, 0, 293, 0, 0),
    data_2 = factor(c(1, 0, 0, 0, 0, 0, 0, 1, 0, 0)),
    customer_id = c(12349, 12350, 12351, 12355, 12363, 12365, 12373, 12384, 12386, 12392),
    first_purchase_cohort = c("Q2-2010", "Q1-2011", "Q4-2010", "Q2-2010", "Q2-2011", "Q1-2011", "Q1-2010", "Q3-2011", "Q4-2010", "Q2-2010"),
    country = c("Italy", "Italy", "Mexico", "Bahrain", "Mexico", "Cyprus", "Austria", "France", "Australia", "Australia")
)

# ******************************************************************************

# Modules (in a separate file and sourced in main shiny app)
module_picker_input_UI <- function(id, label) {
    ns <- NS(id)
    
    if (str_detect(label, "Customer")) {
        multiple = FALSE
    } else {
        multiple = TRUE
    }
    
    tagList(
        
        div(
            style = "margin-left: 10px;",
            class = "col-md-2",
            pickerInput(
                inputId  = ns("picker"),
                label    = h4(label),
                choices  = NULL,
                selected = NULL,
                multiple = multiple,
                options  = list(
                    `actions-box`          = TRUE,
                    `deselct-all-text`     = "Deselect All",
                    `select-all-text`      = "Select All",
                    `none-selected-text`   = "Select Country",
                    `selected-text-format` = "count > 3",
                    liveSearch             = TRUE
                )
            )
        )
    )
}

module_picker_input_Server <- function(id, data = reactive(NULL), var = NULL) {
    moduleServer(
        id,
        function(input, output, session) {
            
            #ns <- getDefaultReactiveDomain()$ns
            
            shiny::observe({
                
                if (var == "customer_id") {
                    updatePickerInput(
                        session  = getDefaultReactiveDomain(),
                        inputId  = "picker",
                        choices  = unique(data() %>% pull({{var}}) %>% sort() %>% as.character()),
                        selected = unique(data() %>% pull({{var}}) %>% sort() %>% as.character())[1],
                    )
                } else {
                    updatePickerInput(
                        session  = getDefaultReactiveDomain(),
                        inputId  = "picker",
                        choices  = unique(data() %>% pull({{var}}) %>% sort() %>% as.character()),
                        selected = unique(data() %>% pull({{var}}) %>% sort() %>% as.character())
                    )
                }
            })
        }
    )
}

# ******************************************************************************

# Shiny app

ui <- fluidPage(
    fluidRow(
        module_picker_input_UI("country", "Country"),
        module_picker_input_UI("cohort", "Purchase Cohort"),
        module_picker_input_UI("customer", "Customer ID")
    ),
    
    br(),
    
    fluidRow(
        tableOutput("table")
    )
  
)

server <- function(input, output, session) {
    
    # Reactive Data
    df_reactive <- reactive({df})
    
    module_picker_input_Server("country", data = df_reactive, var = "country")
    module_picker_input_Server("cohort", data = df_reactive, var = "first_purchase_cohort")
    module_picker_input_Server("customer", data = df_reactive, var = "customer_id")
    
    output$table <- renderTable({
        df_reactive() %>% 
            filter(
                country %in% input[["country-picker"]],
                first_purchase_cohort %in% input[["cohort-picker"]],
                customer_id %in% input[["customer-picker"]]
            )
    })
}

shinyApp(ui, server)

I tried doing something like -

observe({
    
    customer_id_list <- data %>% 
        filter(country %in% input[["country-picker"]]) %>%
        filter(first_purchase_cohort %in% input[["cohort-picker"]]) %>%
        pull(customer_id) %>%
        unique() %>%
        sort()
    
    updatePickerInput(
        session  = getDefaultReactiveDomain(),
        inputId  = "picker",
        choices  = customer_id_list,
        selected = customer_id_list[1],
    )
})

However I'm not sure if my module is written correctly. I'm not sure how to access the country input id in the shiny module.