ModularCSVFileInput.R

# Module UI function
csvFileInputUI <- function(id, label = "CSV file") {
  # Create a namespace function using the provided id
  ns <- NS(id)
  
  tagList(
    fileInput(ns("file"), label),
    checkboxInput(ns("heading"), "Has heading", value = TRUE),
    selectInput(ns("quote"), "Quote", c(
      "None" = "",
      "Double quote" = "\"",
      "Single quote" = "'"
    ))
  )
}


# Module server function
csvFileInputServer <- function( input, output, session, stringsAsFactors ) {
  
  # The selected file, if any
  userFile <- reactive({
    # If no file is selected, don't do anything
    validate(need(input$file, message = FALSE))
    input$file
    
  })
  
  # The user's data, parsed into a data frame
  dataframe <- reactive({
    
    read.csv(userFile()$datapath,
             header = input$heading,
             quote = input$quote,
             stringsAsFactors = stringsAsFactors)
    
  })
  
  # We can run observers in here if we want to
  observe({
    
    msg <- sprintf("File %s was uploaded", userFile()$name)
    cat(msg, "\n")
    
  })
  
  # Return the reactive that yields the data frame
  return(dataframe)
}