Working with a reactive() dataframe inside eventReactive()

shiny
1

Hi everyone. I was hoping someone could provide some guidance on resolving an issue I have. For background, I'm trying to create an interface for users to upload a csv of news stories, which they can then annotate as relevant or not relevant for the purposes of a classifier. What should appear once the user has uploaded a csv is a table output with selectable rows. The text associated with the selected row would then display in the lower right.

The setup I have attempted is to put the user-uploaded spreadsheet into a reactive(), which is then worked with as part of an eventReactive() to annotate sentences as relevant or not. However, the table does not appear when I run the app, and there are no error or warning messages. I've tried modifying my approach to use reactiveValues() and observe() when loading the csv, but I encounter the same issue. I've included the code below, as well as a toy dataset.

I've spent the past couple of hours scouring the web for solutions, but haven't had much luck. Any guidance would be appreciated!

Data

sample <- data.frame(relevant = c('','','','',''), lede=c('first lede', 'second lede', 'third lede', 'fourth lede', 'fifth lede'))
write.csv(sample, 'sample.csv', row.names=F)

Code for app

library(shiny) 
library(DT)


#######################################################
### INTERFACE
#######################################################

in1 <-   radioButtons("truefalse", "Change values in 'keep' column here", 
                      choices=c("TRUE", "FALSE"),
                      selected = "TRUE", inline = FALSE)
in2 <-   actionButton("goButton", "Update Table")
in3 <-   downloadButton("download_data", label = "Download")
in4 <- fileInput('datafile', 'Choose CSV file',
                 accept=c('text/csv', 'text/comma-separated-values,text/plain'))

out1 <- textOutput("text")
out2 <- dataTableOutput("sheet", width = "30%")

in5 <- textInput("save_file", "New file name:", value="updated_data.csv")
in6 <- actionButton("save", "Save updated data")

ui <- fluidPage(titlePanel("Text Annotater"),
                column(6, out2),
                column(6, in4, in1, in2, in5, in6, out1))


#######################################################
### SERVER 
#######################################################
server <- function(input, output){
  
  sheet <- reactive({
    infile <- input$datafile
    if (is.null(infile)) {
      # User has not uploaded a file yet
      return(NULL)
    }
    tbl = read.csv(infile$datapath, stringsAsFactors = FALSE)
    return(tbl)
  })
  

  
  # reactive dataframe object
  df <- eventReactive(input$goButton, {
    if(selected_row_id()>0 &&input$goButton>0){  
      sheet()[selected_row_id(),1] <<- input$truefalse
    }
    sheet()
  }, ignoreNULL = FALSE)
  
  # selectable data table 
  output$sheet <- renderDataTable({
    df()
  }, selection = "single")
  
  # selected row ID from data table
  selected_row_id <- reactive({
    input$sheet_rows_selected
  })
  
  # text of article
  output$text<-renderText({sheet()[input$sheet_rows_selected, "lede"]})
  
  # Save when click the button
  observeEvent(input$save, {
    write.csv(df, input$save_file, row.names = FALSE)
  })
  
  # download button
  output$download_data <- downloadHandler(
    filename = "updated_data.csv",
    content = function(file) {
      write.csv(df(), file, row.names = FALSE)
    }
  )
  
}

shinyApp(ui = ui, server = server)
2

I managed to get this working by storing the data in a reactiveValues(), replacing eventReactive() with observeEvent(), then updating the data using isolate().

Working server code

server <- function(input, output){
  v = reactiveValues(df_sheet = NULL)
  sheet <- reactive({
    infile <- input$datafile
    if (is.null(infile)) {
      # User has not uploaded a file yet
      return(NULL)
    }
    tbl = read.csv(infile$datapath, stringsAsFactors = FALSE)
    v$df_sheet = tbl
    tbl
  })



  # reactive dataframe object
   observeEvent(input$goButton, {
     isolate({
       if(!is.null(selected_row_id())) {
         if (selected_row_id() > 0){  
           v$df_sheet[selected_row_id(),1] <- input$truefalse
         }
       } 
    })
  }, ignoreNULL = FALSE)

  # selectable data table 
  output$sheet <- renderDataTable({
    v$df_sheet[,c(1,2)]
  }, selection = "single")

  # selected row ID from data table
  selected_row_id <- reactive({
    input$sheet_rows_selected
  })

  # text of article
  output$text<-renderText({sheet()[input$sheet_rows_selected, "lede"]})

  # Save when click the button
  observeEvent(input$save, {
    write.csv(v$df_sheet, paste('data/',input$save_file, sep=''), row.names = FALSE)
  })

  # download button
  output$download_data <- downloadHandler(
    filename = "updated_data.csv",
    content = function(file) {
      write.csv(v$df_sheet, paste('data/', file, sep=''), row.names = FALSE)
    }
  )

}

shinyApp(ui = ui, server = server)
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