How to read a csv file in Shiny?

Question

I'm trying to create a shiny dashboard that allows the user to select a csv file. The file contains only two columns that are order number and dateCreated. I want the user to be able to in addition, select the date range that they desire and get a summary count statistic.

So far my code is as follows:

library(shiny)
library(plotly)
library(colourpicker)
library(ggplot2)


ui <- fluidPage(
  titlePanel("Case Referrals"),
  sidebarLayout(
    sidebarPanel(
      fileInput("file", "Select a file"),
      sliderInput("period", "Time period observed:",
                  min(data()[, c('dateCreated')]), max(data()[, c('dateCreated')]),
                  value = c(min(data[, c('dateCreated')]),max(data()[, c('dateCreated')])))
    ),
    mainPanel(
      DT::dataTableOutput("table")
    )
  )
)

# Define the server logic
server <- function(input, output) {
  
  # file input
  input_file <- reactive({
    if (is.null(input$file)) {
      return("")
    }
  })
  
  
  # summarizing data into counts
  data <- input_file()
  data <- subset(data, dateCreated >= input$period[1] & dateCreated <= input$period[2])


  output$table <- DT::renderDataTable({
    data
  })
  
  
  
}

shinyApp(ui = ui, server = server)

I get an error message saying:

Error in data()[, c("dateCreated")]: incorrect number of dimensions

Can anyone help me understand what the problem might be and/or provide a better framework for doing this? And to be clear in the csv file, the createDate variable is broken down into individual days for when the order was placed.

Thank you!

Answer 1

I added comments to the faulty steps.

library(shiny)


ui <- fluidPage(
  titlePanel("Case Referrals"),
  sidebarLayout(
    sidebarPanel(
      fileInput("file", "Select a file"),
      
      # you cannot call data() in your ui. 
      # You would have to wrap this in renderUI inside of your server and use
      # uiOutput here in the ui
      sliderInput("period", "Time period observed:", min = 1, max = 10, value = 5)
    ),
    mainPanel(
      DT::dataTableOutput("table")
    )
  )
)

# Define the server logic
server <- function(input, output) {

  input_file <- reactive({
    if (is.null(input$file)) {
      return("")
    }

    # actually read the file
    read.csv(file = input$file$datapath)
  })

  output$table <- DT::renderDataTable({

    # render only if there is data available
    req(input_file())

    # reactives are only callable inside an reactive context like render
    data <- input_file()
    data <- subset(data, dateCreated >= input$period[1] & dateCreated <= input$period[2])

    data
  })



}

shinyApp(ui = ui, server = server)