Why my application works well but when I try to modularize it, it doesn't work properly ?

Question

[Sib]

Hi there,

My application has two selectInputs. It updates the secound selectInput depending on the first selectInput and then it plots a timeline for df data. The app works completely well, but when I try to modularize it, it doesn't work properly (just the selectInputs work, but no plot is built). I have created a minimal example. I really appreciate any help everybody can provide.

library(shiny)
library(plotly)
library(reshape2)

# data preparation
df<-data.frame(Name1<-c("Aix galericulata","Grus grus","    Alces alces"),
               Name2<-c("Mandarin Duck","Common Crane"  ,"Elk"),
               eventDate<-c("2015-03-11","2015-03-10","2015-03-10"),
               individualCount<-c(1, 10, 1)
)
colnames(df)<-c("Name1","Name2","eventDate","individualCount")

#----------------------------------------------------------------------------------------
# module dataselect
dataselect_ui<- function(id) {
  ns<-NS(id)
  tagList(
    selectInput(ns("Nametype"),"Select a name type",
                choices=c("Name1","Name2","choose"),selected = "choose"),

    selectInput(ns("Name"),"Select a name",
                choices="",selected = "",selectize=TRUE)
  )
}
dataselect_server <- function(id) {
  moduleServer(id, function(input, output, session) {


    # Putting columns Name1 and Nam2 of df in one column called nameType using melt()function
    # This format of data is needed for the choices argument of updateSelectizeInput()
    df2<-reshape2::melt(df,id=c("eventDate","individualCount"))
    colnames(df2)<-c("eventDate","individualCount","nameType","Name")

    observeEvent(
      input$Nametype,
      updateSelectizeInput(session, "Name", "Select a name", 
                           choices = unique(df2$Name[df2$nameType==input$Nametype]),selected = ""))


    # finalDf() is the data used to plot the timeline
    finalDf<-reactive({
      if(input$Name=="choose"){
        return(NULL)

      }
      if(input$Name==""){
        return(NULL)

      }
      if(input$Nametype=="choose"){
        return(NULL)

      } 

      # if the first selectInput is set to Name1, from df select rows their Name1 column is 
      # equal to the second selectInput value
      else if(input$Nametype=="Name1"){
        finalDf<-df[which(df$Name1==input$Name) ,]

      } 
      # if the first selectInput is set to Name2, from df select rows their Name2 column is 
      # equal to the second selectInput value
      else if(input$Nametype=="Name2"){
        finalDf<-df[which(df$Name2==input$Name) ,]

      }
      return(
        reactive({
          input$Name
        })
      )

    })
  })
}

#-------------------------------------------------------------------------------------

# application
ui <- fluidPage(

  # Application title
  navbarPage(
    "app",
    tabPanel("plot", 
             sidebarPanel(

               dataselect_ui("dataselect")

             ),

             mainPanel(
               plotlyOutput("timeline")

             )

    )
  )
)


server <- function(session,input, output) {

  dataselect_server("dataselect")
  # timeline plot
  output$timeline <- renderPlotly({
    req(input$Name)
    p<-ggplot(finalDf(),aes(x=eventDate,y=individualCount)) +geom_point(alpha=0.2, shape=21, color="black",fill="red",size=5)+
      labs( x = "Date Event",y= "Individual Count") +theme_bw()
    p<-ggplotly(p)
    p
  })

}

shinyApp(ui = ui, server = server)

Answer 1

[Istvan Albert]

The code is too long for me to go through, but from the problem you are having I expect that it has to do with scope (the block where a variable is visible and what value it has).

As an example, here is this piece of code. What do you think it prints?

msg <- "Hello!"

foo <- function (){
  msg <- "Good bye!"
}

foo()

print(msg)

the msg variable will carry different information in different frames.

Answer 2

[Sib]

The question was solved here: https://stackoverflow.com/questions/74572339/why-my-application-works-well-but-when-i-try-to-modularize-it-it-doesnt-work-p