RShiny: dataTableProxy: selectPage isn't navigating to any page: 'page index out of range'

Question

Before starting, I've tried consulting this question, this question and the documentation for dataTableProxy().

I'm currently trying to have a basic RShiny application that, upon loading, automatically navigates to a given page and selects a given row(later on I plan to have the application do so based on a GET query string, but am currently using this basic version as a starting point). The table in question has 32 rows and 4 pages. The contrast to the questions I consulted is that they do so through an event trigger, while I want to do so on document loading.

Selecting the row and page is straightforward enough with selectRows() and selectPage(). selectRows() provides the expected result; however, selectPage() does not seem to work for me, throwing a 'page index out of range' in the browser console. In my example code, I select row 25 and navigate to page index 2. Even trying to select page index 0 throws an 'out of range' error.

I've provided my application code below. I'm wondering if I'm trying to navigate to a page before the table even paginates?

Any input is greatly appreciated.

EDIT: I have a way to both select the row and go to a page, shown below. However, even though I go to page index 2, the contents of page index 0 are still presented. So I have to click to a different page and then back to page index 2 to see my selected row.

~ Callen

library(DT)
library(shiny)
library(shinyjs)

ui <- fluidPage(
    tags$head(tags$script(src="datatables.min.js")),
    fluidRow(
        DT::dataTableOutput("mtcar_table")
    )
)

server <- function(input, output, session){
    which_page <<- 0
    which_row <<- 0
    observe({
        which_row <<- 25
        which_page <<- floor(which_row/10)
        output$mtcar_table = DT::renderDataTable({
            # I know here I can normalize
            # by the table state's rows per page attribute
            # but want to just get this base exmaple
            # to work first
            return(
                mtcars
            )
        },
            options = list(
                initComplete = JS(
                    "function(settings, json){",
                    "$(this.api().table().page(2).draw('page'));",
                    "console.log(this); return this;}"
                )
            )
        )
        # making sure I'm still recording the row
        # and page number
        print(which_row)
        print(which_page)
        # manipulating the table here to navigate
        # to the right page and row.
        # I constantly get "page index out of range"
        # even if I put down page {0, 1}. I'm wondering
        # if I'm trying to navigate to the page before
        # the pagination actually takes place?
        dataTableProxy("mtcar_table") %>%
            selectRows(which_row)
    })
}

shinyApp(ui, server)

Answer 1

Upon loading you can use options and selection arguments passed via ... to renderDataTable like this:

library(DT)
library(shiny)

ui <- fluidPage(
    tags$head(tags$script(src="datatables.min.js")),
    fluidRow(
        DT::dataTableOutput("mtcar_table")
    )
)

server <- function(input, output, session){
        
        output$mtcar_table <-  renderDataTable({
                mtcars
        },
        options = list(displayStart = 20),  
        selection = list(mode = 'multiple', selected = c(25), target = 'row') )
}

shinyApp(ui, server)