Warning in processWidget(instance) using renderDataTable and Shiny

Question

I am getting this warning every time I run my shiny App.

Warning in processWidget(instance) : renderDataTable ignores ... arguments when expr yields a datatable object; see ?renderDataTable

This is a reproducible example:

library(shiny)
library(DT)

ui <- fluidPage(
                titlePanel("My app"),
                sidebarLayout(
                  sidebarPanel(
                  ),
                  mainPanel(
                    dataTableOutput("table")
                    )
                )
)


server <- function(input, output, session) {

  output$table <- renderDataTable({

      datatable(
        mtcars,
        filter = list(position = 'top', clear = FALSE),
        selection = "none", #this is to avoid select rows if you click on the rows
        rownames = FALSE,
        extensions = 'Buttons',
        
        options = list(
          scrollX = TRUE,
          autoWidth = TRUE,
          dom = 'Blrtip',
          buttons =
            list('copy', 'print', list(
              extend = 'collection',
              buttons = list(
                list(extend = 'csv', filename = "file", title = NULL),
                list(extend = 'excel', filename = "file", title = NULL)),
              text = 'Download'
            )),
          lengthMenu = list(c(10, 30, 50, -1),
                            c('10', '30', '50', 'All'))
        ),
        class = "display"
      )
    
  },rownames=FALSE)
}
  
  
shinyApp(ui, server)

I checked this post but I am not using the parameter filter at the end. I am using it inside DT::datatable. What is more, if I comment this line (filter = list(position = 'top', clear = FALSE)), I am still getting the same warning. So it must be because of another reason.

Does anyone know how to fix it?

Thanks in advance

Answer 1

rownames is not part of the arguments of DT::renderDataTable() so it is passed in ... in this function. But the documentation of DT::renderDataTable() says:

... [is] ignored when expr returns a table widget, and passed as additional arguments to datatable() when expr returns a data object

Here, you create a datatable in renderDataTable() so ... (and hence rownames = FALSE) is ignored. This argument is useless here so you can remove rownames = FALSE and it will remove the warning.