I am currently trying to make an application that takes in a large data frame and then filters based on a column from the uploaded data frame, before displaying a table for the user. When I try to filter based on the value of the dependent input, I receive an error that the filter value must be ‘[size of the data frame] or 1, not size 0’. I can render the output of the value, just not filter with it.

I’m new to writing modules, so there may be something very obvious that I am missing, but I have not been able to work it out yet.

#Reprex modules

library(shiny)
library(bslib)
library(DT)


testUI<-function(id){
  
  ns<-NS(id)
  tagList(
    layout_columns(selectInput(ns("carb"), "Carb", choices = seq(1:10), selected = 4),
                   uiOutput(ns("cyl"))),
    tableOutput(ns("table")),
    tableOutput(ns("table_ouput"))
    # textOutput(ns("cyl_text"))
    
  )
  
}

###initial filter function in UI to make dynamic dummy dataframe
fetchServer <- function(id) {
  
  moduleServer(id, function(input, output, session) {
    
    ns<-session$ns
    
     return(reactive(input$carb))
    
  })
}

##the initial data frame where the filtering column is located
testServer <- function(id, .carb) {

  moduleServer(id, function(input, output, session) {

    ns<-session$ns

    data<-reactiveValues(data = NULL)
    
    observe(data$data<-mtcars%>%filter(carb == .carb()))

    output$table<-renderTable(data$data)

    return(reactive(data$data))
      })

}

##rendering the values from the filtering column in the module's UI
cylServer <- function(id, carb_data) {
  
  moduleServer(id, function(input, output, session) {
    
    ns<-session$ns
    
    output$cyl<-renderUI({
      
      selectInput(
              ns("cyl"), 
              "Cyl", 
              choices = carb_data()$cyl)
      
      
    })
    
    return(reactive(input$cyl))
    
  })
}

##attempting to filter based on the user's selection of the rendered UI element
new_tableServer <- function(id, .cyl) {

  moduleServer(id, function(input, output, session) {

    ns<-session$ns

    data<-reactiveValues(data = NULL)

    observe(data$data<-mtcars%>%filter(cyl == .cyl()))

    output$table_output<-renderTable(data$data)
    
    # output$cyl_text<-renderText(.cyl())

    })

}

#Reprex App

ui <- page(
  
    testUI("x1")

    )


server <- function(input, output) {

carb<-fetchServer("x1")
data<-testServer("x1", carb)
cyl<-cylServer("x1", data) 
new_tableServer("x1", cyl)
}


shinyApp(ui = ui, server = server)