A general shiny app to import and export data to R. Note that this can be used as a starting point for any app that requires data to be loaded into Shiny.

## global.R
library("shiny")
library("foreign")

## server.R
shinyServer(function(input, output) {

  ### Argument names:
  ArgNames <- reactive({
    Names <- names(formals(input$readFunction)[-1])
    Names <- Names[Names!="..."]
    return(Names)
  })

  # Argument selector:
  output$ArgSelect <- renderUI({
    if (length(ArgNames())==0) return(NULL)

    selectInput("arg","Argument:",ArgNames())
  })

  ## Arg text field:
  output$ArgText <- renderUI({
    fun__arg <- paste0(input$readFunction,"__",input$arg)

    if (is.null(input$arg)) return(NULL)

    Defaults <- formals(input$readFunction)

    if (is.null(input[[fun__arg]]))
    {
      textInput(fun__arg, label = "Enter value:", value = deparse(Defaults[[input$arg]]))
    } else {
      textInput(fun__arg, label = "Enter value:", value = input[[fun__arg]])
    }
  })


  ### Data import:
  Dataset <- reactive({
    if (is.null(input$file)) {
      # User has not uploaded a file yet
      return(data.frame())
    }

    args <- grep(paste0("^",input$readFunction,"__"), names(input), value = TRUE)

    argList <- list()
    for (i in seq_along(args))
    {
      argList[[i]] <- eval(parse(text=input[[args[i]]]))
    }
    names(argList) <- gsub(paste0("^",input$readFunction,"__"),"",args)

    argList <- argList[names(argList) %in% ArgNames()]

    Dataset <- as.data.frame(do.call(input$readFunction,c(list(input$file$datapath),argList)))
    return(Dataset)
  })

  # Select variables:
  output$varselect <- renderUI({

    if (identical(Dataset(), '') || identical(Dataset(),data.frame())) return(NULL)

    # Variable selection:
    selectInput("vars", "Variables to use:",
                names(Dataset()), names(Dataset()), multiple =TRUE)
  })

  # Show table:
  output$table <- renderTable({

    if (is.null(input$vars) || length(input$vars)==0) return(NULL)

    return(Dataset()[,input$vars,drop=FALSE])
  })


  ### Download dump:

  output$downloadDump <- downloadHandler(
    filename = "Rdata.R",
    content = function(con) {

    assign(input$name, Dataset()[,input$vars,drop=FALSE])

    dump(input$name, con)
    }
  )

  ### Download save:

  output$downloadSave <- downloadHandler(
    filename = "Rdata.RData",
    content = function(con) {

      assign(input$name, Dataset()[,input$vars,drop=FALSE])

      save(list=input$name, file=con)
    }
  )

})


## ui.R

shinyUI(pageWithSidebar(

  # Header:
  headerPanel("R data reader"),

  # Input in sidepanel:
  sidebarPanel(
    tags$style(type='text/css', ".well { max-width: 20em; }"),
    # Tags:
    tags$head(
      tags$style(type="text/css", "select[multiple] { width: 100%; height:10em}"),
      tags$style(type="text/css", "select { width: 100%}"),
      tags$style(type="text/css", "input { width: 19em; max-width:100%}")
    ),

    # Select filetype:
    selectInput("readFunction", "Function to read data:", c(
      # Base R:
      "read.table",
      "read.csv",
      "read.csv2",
      "read.delim",
      "read.delim2",

      # foreign functions:
      "read.spss",
      "read.arff",
      "read.dbf",
      "read.dta",
      "read.epiiinfo",
      "read.mtp",
      "read.octave",
      "read.ssd",
      "read.systat",
      "read.xport",

      # Advanced functions:
      "scan",
      "readLines"
      )),

    # Argument selecter:
    htmlOutput("ArgSelect"),

    # Argument field:
    htmlOutput("ArgText"),

    # Upload data:
    fileInput("file", "Upload data-file:"),

    # Variable selection:
    htmlOutput("varselect"),

    br(),

    textInput("name","Dataset name:","Data"),

    downloadLink('downloadDump', 'Download source'),
    downloadLink('downloadSave', 'Download binary')

  ),

  # Main:
  mainPanel(

    tableOutput("table")

  )
))