Multiple UI Output Based on File Upload Using Shiny Modules - r

Question

Dataset Viewer
Hello, I am attempting to create a shiny application that allows to user to view their uploaded datasets individually.
When there is no file uploaded a message appears asking the user to upload their file...once a csv file is uploaded, the message disappears and shows the users uploaded datasets.
What I've tried
I've tried: using conditionalPanels in app.R & upload.R, creating a separate R file exclusively for each ui condition. I believe my issue is that output$table (function that renders mainpanel ui) is not being triggered after the file uploads.
My issue
Once the user uploads a csv file(any readable csv file), the pre-existing message is not being replaced by the uploaded datasets.
upload.R
data = list()
numDatasets = 0
uploadSideUI <- function(id) {
ns <- NS(id)
tagList(
h2("Dataset Viewer"),
fileInput(ns("file"),label = "Upload File", multiple = FALSE, accept = ".csv")
)
}
uploadMainUI <- function(id) {
ns <- NS(id)
uiOutput(ns("table"))
}
uploadServer <- function(id) {
moduleServer(id, function(input,output,session){
observeEvent(eventExpr = input$file,
handlerExpr = {
df <- read.csv(file = input$file$datapath,header = FALSE)
data <<- c(data,list(df))
numDatasets <<- numDatasets + 1
})
output$table <- renderUI({
if(numDatasets ==0){
h2("please upload file")
}else{
req(input$file)
print(numDatasets)
lapply(1:numDatasets,function(i) {
dataframe = data[[i]]
tagList(
h2(paste("dataset",i)),
hr(),
datatable(dataframe,rownames = FALSE, option = list(scrollY="300px",searching=FALSE)),
br()
)
})
}
})
})
}
app.R
#app.R
library(DT)
library(shiny)
source("testModule.R")
ui <- fluidPage(
sidebarLayout(
sidebarPanel(
uploadSideUI("uploadPage")
),mainPanel(
uploadMainUI("uploadPage")
)
)
)
server <- function(input, output, session) {
uploadServer("uploadPage")
}
shinyApp(ui = ui, server = server)
I am new to the modulization process in shiny, so if you have any other suggestions please point them out! Thanks in advance!

Answer 1

Try this
uploadServer <- function(id) {
moduleServer(id, function(input,output,session){
rv <- reactiveValues(numDatasets = 0)
observeEvent(eventExpr = input$file,
handlerExpr = {
df <- read.csv(file = input$file$datapath,header = FALSE)
data <<- c(data,list(df))
rv$numDatasets <<- rv$numDatasets + 1
})
output$table <- renderUI({
if(rv$numDatasets == 0){
h2("please upload file")
}else{
req(input$file)
print(rv$numDatasets)
lapply(1:rv$numDatasets,function(i) {
dataframe = data[[i]]
tagList(
h2(paste("dataset",i)),
hr(),
datatable(dataframe,rownames = FALSE, option = list(scrollY="300px",searching=FALSE)),
br()
)
})
}
})
})
}