R Shiny: how to use a dataframe variable from server.R in ui.R

Question

I am trying to use the values$df dataframe variable from server.R in ui.R to display all the field names of the dataframe as checkbox in the side panel. But I get an error saying Error: object 'values' not found.

Here is what I have in the server.R file:

  values<- reactiveValues() 
  values$df<- data.frame() # creates an empty dataframe

  # actionButton 
  mdf<- eventReactive(input$click_counter, {
    name<- input$name
    gender<- input$gender
    college<- input$college
    team<- input$team
    score<- input$score

    new_row<- data.frame(name,college,gender,team,score)

    return(new_row)
  })

  observeEvent(input$click_counter, {
    name<- input$name
    gender<- input$gender
    college<- input$college
    team<- input$team
    score<- as.numeric(input$score) # convert to numeric here to make sorting possible
    rank<- 0


    new_row<- data.frame(rank,name,college,gender,team,score)


    values$df<- rbind(values$df, new_row)
    values$df<- values$df[order(-values$df$score),]
    values$df$rank<- 1:nrow(values$df)
  })

  output$nText<- renderDataTable({
    mdf()
  })

  output$nText2<- renderDataTable({
    values$df
  }, options = list(orderClasses = TRUE,lengthMenu = c(5, 10, 30), pageLength = 5))

And this is what I have in the ui.R file:

sidebarLayout(
  sidebarPanel(
    checkboxGroupInput('nText2',
                       'Columns in players to show:',
                       names(values$df),
                       selected = names(values$df))
  ),

You haven't initialized values anywhere in your code, so it can't run rbind(values$df, new_row) — Gaurav Bansal
I'd also recommend that you move your checkboxGroupInput() to the server side with renderUI() and then just call the htmlOutput("nText2") in the user interface. This will allow the UI to be dependent on the outcome of the server side operation. Calling the reactive value from the server in the UI as values$df is not generally how the UI interacts with the server. — Ryan Morton
You are trying to access values defined outside a reactive function. Try isolate(values$df) on UI side — user5249203

nteetor nteetor · Accepted Answer · 2017-03-01T15:24:42

I am not quite sure when you assign the values object. However, if you are not already using a global.R file I suggest using one. In it you can assign values and the object will be available in both server.R and ui.R. Place global.R in the same folder as the two other files.

R Shiny: how to use a dataframe variable from server.R in ui.R

2 Answers