Warning in processWidget(instance) using renderDataTable and Shiny - r

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.