The button 'Delete Rows" not working in R shiny

Question

I'm making a R shiny app with features such as browse, SpitColumn, and Delete Rows, Replacing values, and Remove columns. Everything works OK except for 'Delete Rows,' which works fine before I add the observeEvent(input$downloadbtn) to the server function.

Could some help me to fix it?

Overview of the code Basically The code accepts a CSV file as input and, depending on the issue, I use the "SplitColumns" and "Delete Rows" and "Replace Values" buttons in the app, however, I'd like to add another button called "Remove Column" now.

'Overview of the app

csv data

ID  Type   Range
21  A1 B1   100
22  C1 D1   200
23  E1 F1   300

app.R

library(shiny)
library(reshape2)
library(DT)
library(tibble)


###function for deleting the rows
splitColumn <- function(data, column_name) {
  newColNames <- c("Unmerged_type1", "Unmerged_type2")
  newCols <- colsplit(data[[column_name]], " ", newColNames)
  after_merge <- cbind(data, newCols)
  after_merge[[column_name]] <- NULL
  after_merge
}
###_______________________________________________
### function for inserting a new column

fillvalues <- function(data, values, columName){
  df_fill <- data
  vec <- strsplit(values, ",")[[1]]
  df_fill <- tibble::add_column(df_fill, newcolumn = vec, .after = columName)
  df_fill
}

##function for removing the colum

removecolumn <- function(df, nameofthecolumn){
  df[ , -which(names(df) %in% nameofthecolumn)]
}

### use a_splitme.csv for testing this program

ui <- fluidPage(
  sidebarLayout(
    sidebarPanel(
      fileInput("file1", "Choose CSV File", accept = ".csv"),
      checkboxInput("header", "Header", TRUE),
      actionButton("Splitcolumn", "SplitColumn", class = "btn-warning" ),
      uiOutput("selectUI"),
      
      
      actionButton("replacevalues", label = 'Replace values', class= "btn-Secondary"),
      actionButton("removecolumn", "Remove Column"),
      actionButton("Undo", 'Undo', style="color: #fff; background-color: #337ab7; border-color: #2e6da4"),
      actionButton("deleteRows", "Delete Rows"),
      textInput("textbox", label="Input the value to replace:"),
      actionButton('downloadbtn', label= 'Download'),
    ),
    mainPanel(
      DTOutput("table1")
    )
  )
)

server <- function(session, input, output) {
  rv <- reactiveValues(data = NULL, orig=NULL)
  
  observeEvent(input$file1, {
    file <- input$file1
    ext <- tools::file_ext(file$datapath)
    
    req(file)
    
    validate(need(ext == "csv", "Please upload a csv file"))
    
    rv$orig <- read.csv(file$datapath, header = input$header)
    rv$data <- rv$orig
  })
  
  output$selectUI<-renderUI({
    req(rv$data)
    selectInput(inputId='selectcolumn', label='select column', choices = names(rv$data))
  })
  
  
  observeEvent(input$Splitcolumn, {
    rv$data <- splitColumn(rv$data, input$selectcolumn)
  })
  
  observeEvent(input$deleteRows,{
    if (!is.null(input$table1_rows_selected)) {
      rv$data <- rv$data[-as.numeric(input$table1_rows_selected),]
    }
  })
  
  output$table1 <- renderDT(
    rv$data, selection = 'none', server = F, editable = T
  )
  #includes extra column after the 'select column' and replaces the values specified 'Input the value to replace:'
  observeEvent(input$replacevalues, {
    rv$data <- fillvalues(rv$data, input$textbox, input$selectcolumn)
  })
  #Removing the specifield column through select column
  observeEvent(input$removecolumn, {
    rv$data <- removecolumn(rv$data,input$selectcolumn)
  })
  observeEvent(input$Undo, {
    rv$data <- rv$orig
  })
  #Storing the csv file through download button
  observeEvent(input$downloadbtn,{
    write.csv(rv$data,'test.csv')
    print ('file has been downloaded')
  })
  observeEvent(input$downloadbtn, {
    showModal(modalDialog(
      title = "Download Status.",
      paste0("csv file has been downloaded",input$downloadbtn,'.'),
      easyClose = TRUE,
      footer = NULL
    ))
  })
}

shinyApp(ui, server)

Answer 1

You just need to remove the selection = 'none' argument from the renderDT function so you can select a row, then your button works as expected.