Unecessary "Datatables warning" alert when creating a DT with new data and same number of columns

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
35/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Stale
Tech stack
javascript, r
Domain
frontend, web-dev

Research direction

Start with the reproducible Shiny app, especially the DTOutput() inside renderUI() and the renderDT()/datatable() sequence after hiding and showing the table. Reproduce the warning, then trace the DataTables alert behavior and verify that the unnecessary warning is removed without suppressing legitimate alerts.

Written by the indexing model from the issue text.

Description

I'm writing an app that creates certain reports at the click of a button. When a new report has the same number of columns as the previous one, DT throws an alert about how column name from old data is not present in new data, that needs to be clicked through. After that, it creates the correct table without issue! This obviously makes for poor UX since it seems something has gone wrong when, in fact, everything went OK.

I'm pretty sure the issue is that the DTOutput() function is a part of a renderUI() call. It doesn't seem likely I can move away from this since I need to make some checks before displaying or hiding the table. Here is a simplified version as a reproducible example:

library(shiny)
library(DT)

ui <- fluidPage(
  actionButton("change_col", "Change column names"),
  actionButton("hide_table", "Hide/Show table"),
  uiOutput("custom_ui")
)


server <- function(input, output, session) {
  output$custom_ui <- renderUI({
    # this req() simulates that my app needs to check some reactive values to
    # determine whether to show or hide the table
    req(input$change_col)
    
    # The UI programatically decides whether to show the table.
    if (input$hide_table %% 2 == 1) return(h2("NO DATA"))
    
    DT::DTOutput("my_table")
  })

  
  output$my_table <- renderDT({
    req(input$change_col)
    my_data <- iris

    # the number of columns is always the same, 
    # but the column names differ each run
    new_colnames <- paste(colnames(iris)[1:5], 
                          rnorm(5)
                          )
    
    
    
    colnames(my_data)[1:5] <- new_colnames

    DT::datatable(my_data,
                  # HTML ne renderaj kao string nego stvarni HTML
                  escape = F,
                  selection = "none",
                  rownames = FALSE,
                  options = list(
                    dom = 'tp',
                    ordering = F,
                    language = list(zeroRecords = "Nema podataka za prikaz",
                                    paginate = list('next' =  "Sljedeća",
                                                    'previous' = "Prethodna")
                    ),
                    scrollX = TRUE,
                    searching = F)
    )
  })
}

shinyApp(ui, server)

To reproduce, click on Change column names, Click on Hide/Show twice, and then Change column names again.

Do you have any suggestions as how to avoid this alert?

One solution I've found is to add a callback that disables DT alerts (adding callback = DT::JS("$.fn.dataTable.ext.errMode = 'none';") to the datatable() call). I'm not happy with that since if there were any legitimate alerts, this would disable them too.

Dominant language
JavaScript
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Forks
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