If Statement in Shiny based on values in reactive

Question

I am building an authentication part in my app by comparing the code sent in email and the code users submit. I have tried adding if-statement by using either in reactive(),isolate(), renderTable(). I either get the value should be in the reactive part error, or the app does not respond at all. Below is what I have in Server.R, the app does not respond at all with no error.

            shinyServer(function(input, output, session) {      
              myData <- reactive({
                req(input$Id)
                #connect to the database, get the data, res
                #send an email with random number, rnd
                list(res,rnd)
              })

              output$tbTable <- renderTable({req(input$Auth)
                  if (input$AuthCode==myData()$rnd) {
                myData()$res
              }
              else{
                as.data.frame(c("Authentication Failed"))
              }
              })
              output$downloadData <- downloadHandler(
                filename = function() {
                  paste(input$Id, " filname.xlsx", sep = "")
                },
                content = function(file) {
                  write.csv(myData(), file, row.names = FALSE)
                }
              )#this part need to depend on the if-statement as well
            }
            )

UI.R

                ui <- shinyUI(fluidPage(title = "aaa",
                titlePanel("aaa"),
                sidebarLayout(
                  sidebarPanel(

                    textInput("Id", "Enter Acct Name below"),
                    submitButton(text="Submit"),
                    tags$hr(),
                    numericInput("AuthCode",label="Authentication",value=""),
                    actionButton("Auth",label="Submit"),
                    tags$hr(),
                    tags$hr(),
                    downloadButton("downloadData", "Download Data")
                  ),
                  mainPanel(
                    tabsetPanel(
                      tabPanel("Data", tableOutput("tbTable"))
                    )) 
                ),
            )
            )

why have you used this expression `as.data.frame(c("Authentication Failed"))` ? — amrrs, Sep 07 '18 at 14:28
I am not quite clear about the data structure in Shiny. As res, the output is a dataframe, so I converted this string to dataframe to avoid mismatch. Appreciate if any input on the adverse affect if it is the problem. — May Y, Sep 07 '18 at 14:40
Are you okay if there is a modal box saying authentication failed? — amrrs, Sep 07 '18 at 14:43
And why do you have the first submit button, can't it be one button for both account and authentication code? — amrrs, Sep 07 '18 at 14:54
The email is supposed to be sent to a changeable email address based on input$Id, like the account owner, for authentication. So after the submit triggers the email, the correct recipient will enter the code in the email for authentication. So I guess there has to be 2 buttons. — May Y, Sep 07 '18 at 14:58
Cool. You had used `submit` there which is another issue. got it! — amrrs, Sep 07 '18 at 14:59
I read post about actionButton is preferred, but submitButton works well in older version without adding the authentication part. Really appreciate if you can help me understand this. — May Y, Sep 07 '18 at 15:04

score 0 · Accepted Answer · answered Sep 07 '18 at 15:16

I think I've got the fixed to do what you want. Please check. I've done the following changes

Replaced your submitButton to actionButton as Acc and using observeEvent to call that.
The authentication is also now triggered by an observeEvent when the second button is clicked
Excel extension wouldn't work in write.csv so changed the extension.

server.R

shinyServer(function(input, output, session) {      


# the first button will trigger this  


  observeEvent(input$Acc,{
  #  myData <- reactive({
      req(input$Id)
      #connect to the database, get the data, res
      #send an email with random number, rnd
      #list(res,rnd)
     myData <<- list(res = 123,rnd = 345) #passing test value and storing it as global variable for accessing in other functions
   # })

    cat("mydata done")

  })


  # the second button will trigger this
  observeEvent(input$Auth,{

    output$tbTable <- renderTable({
      #req(input$Auth)
      if (input$AuthCode==myData$rnd) {
        myData$res
      }
      else{
        #as.data.frame(c("Authentication Failed"))
        shiny::showModal(modalDialog(
          title = "Important message",
          "Authentication Failed!"
        ))
      }
    })
  })


  output$downloadData <- downloadHandler(
    filename = function() {
      paste(input$Id, " filname.csv", sep = "") #renamed it to csv because write.csv writes to csv not excel
    },
    content = function(file) {
      write.csv(myData, file, row.names = FALSE)
    }
  )#this part need to depend on the if-statement as well
}
)

ui.R

ui <- shinyUI(fluidPage(title = "aaa",
                        titlePanel("aaa"),
                        sidebarLayout(
                          sidebarPanel(

                            textInput("Id", "Enter Acct Name below"),
                            actionButton("Acc",label="Click to send code"),
                            tags$hr(),
                            numericInput("AuthCode",label="Authentication",value=000),
                            actionButton("Auth",label="Submit"),
                            tags$hr(),
                            tags$hr(),
                            downloadButton("downloadData", "Download Data")
                          ),
                          mainPanel(
                            tabsetPanel(
                              tabPanel("Data", tableOutput("tbTable"))
                            )) 
                        )
)
)

If Statement in Shiny based on values in reactive

1 Answers1

server.R

ui.R