Simple Shiny survey that pushes data to a Dropbox folder

server.R

# devtools::install_github("duncantl/ROAuth")
# devtools::install_github("karthik/rDrop")
library(ROAuth)
library(rDrop)
load('my_dropbox_credentials.rdata') #credentials object from rDrop instructions

shinyServer(function(input, output) {

    output$Main <- renderUI({
        dynamicUi()
    })

    dynamicUi <- reactive({

        if(input$Finish == 0L){
            return(NULL)
        } else {
            if(input$firstname == '') return(stop('Missing First Name input!'))
            if(input$lastname == '') return(stop('Missing Last Name input!'))
            got <- c(input$LVMFA, input$Issues, input$Regression, input$GLVM,
                     input$Green, input$Review)
            if(length(unique(got)) <= 2L){
                msg <- paste0(input$firstname, ', your responses contain little to no
                                   variability; please think more carefully about your book choices
                                   and rate them accordingly.')
                msg <- gsub('\n', ' ', msg)
                return(stop(msg))
            }
            ret <- rank(as.numeric(got))
            dropbox_save(dropbox_credentials, ret,
                         file=paste0(input$firstname,input$lastname),
                         verbose=FALSE, ext=".Rdata")
            return(h3('Thank you for completing the form! Your responses have been uploaded sucessfully.
                      It is now safe to close your browser.'))
        }

    })
})

ui.R

shinyUI(pageWithSidebar(

    headerPanel('SCS Reading List, 2014-2015'),

    sidebarPanel(
        h3(' Please fill in the following:'),
        textInput(inputId = 'firstname', label = ' First Name:', value =''),
        textInput(inputId = 'lastname', label = ' Last Name:', value =''),

        hr(),
        h5('Upon completion, click the following button to submit your responses.'),
        actionButton("Finish", "Click Me! I'm the button!"),

        uiOutput("Main")
    ),

    mainPanel(
        h4('Rate the following books for the SCS seminar (1 = Most Wanted, 6 = Least Wanted).'),
        hr(),

        sliderInput(inputId = "LVMFA", min = 1, max=6, step = 1, value=3,
                     label = "Latent Variable Models and Factor Analysis: A Unified Approach"),
        br(),br(),

        sliderInput(inputId = "Issues", min = 1, max=6, step = 1, value=3,
                    label = " Contemporary Issues in Exploratory Data Mining in the
                    Behavioral Sciences"),
        br(),br(),

        sliderInput(inputId = "Regression", min = 1, max=6, step = 1, value=3,
                     label = "Regression Modeling Strategies: With Applications to Linear Models,
                       Logistic Regression, and Survival Analysis"),
        br(),br(),

        sliderInput(inputId = "GLVM", min = 1, max=6, step = 1, value=3,
                     label = "Generalized latent variable modeling: Multilevel, longitudinal and
                       structural equation models "),
        br(),br(),

        sliderInput(inputId = "Green", min = 1, max=6, step = 1, value=3,
                     label = "Little Green Books"),
        br(),br(),

        sliderInput(inputId = "Review", min = 1, max=6, step = 1, value=3,
                     label = "The reviewer's guide to quantitative methods in the social sciences")

    )

))