Select DT rows when input IDs are unknown

[Isam Haddad]

Hey there,

I create an unknown number of datatables dynamically and encapsulate them in a tagList which is rendered by renderUI. Using this approach, the outputIDs of the tables are unknown. How can I then access the selected rows?

Typically this would work:

server = function(input, output) {
  output$tbl <- renderDataTable(
    DT::datatable(data.frame("data"))
  )
  observeEvent({ input$tbl_rows_selected },
    ...
  )
})

However, In my case I have no idea how to achieve this. Here is a minimal example:

shinyApp(
  ui=fluidPage(
    mainPanel(
      uiOutput("tabs"),
      dataTableOutput("you_need_me")
    )
  ),
  server=function(input, output) {
    output$tabs <- renderUI({
      tables <- lapply( list("dt1", "dt2", "dt3"), function(x){
        renderDataTable( DT::datatable( data.frame( "data" )))
      })
      tagList(tables)
    })
   
    observeEvent({
      # this does not work since the ids are unkown
      input$dt1_rows_selected
      input$dt2_rows_selected
      input$dt3_rows_selected
    },{
      # ... do something with the selected row
    })
  })
)

Any help is appreciated.

Thanks, Isam

 

[Yihui Xie]

You are supposed to use UI functions (e.g. dataTableOutput()) inside
renderUI(). I don't understand what it means to use renderDataTable()
in renderUI(). renderDataTable() is supposed to be assigned to
output$tableId (where tableId may be dt1, dt2, dt3 in your case).

Regards,
Yihui

[Yihui Xie]

Just for the record: http://stackoverflow.com/q/31787709/559676

Regards,
Yihui

[Isam Haddad]

Thank you so much for clarifying and pointing me into the right direction. The example I showed was influenced by another problem I had earlier and which was answered here: https://stackoverflow.com/questions/31749339/reactivity-of-dynamic-number-of-ui-elements

I managed to solve both problems with the following solution:

shinyApp(

  ui = fluidPage(

    mainPanel(

      uiOutput("tabs")

    )

  ),

  server = function(input, output) {

    output$tabs <- renderUI({

      tables <- lapply( list("dt1", "dt2", "dt3"), function(x){

        local({

          output[[x]] <- renderDataTable( DT::datatable( data.frame("data") ) )

        })

        observeEvent({

          input[[paste( x, "rows_selected", sep="_" )]]

        },{

          print( paste( x, ":", input[[paste( x, "rows_selected", sep="_" )]] ) )

        })

        dataTableOutput( x )

      })

      tagList(tables)

    })

  }

)

If no one sees another problem with this code, for completeness sake I'd answer both questions on SO accordingly.

Thanks!

[Yihui Xie]

Thanks for the solution! I'd suggest you move renderDataTable() and
observeEvent() out of renderUI(), although in this particular case it
probably does not matter:

library(shiny)

shinyApp(
ui = fluidPage(
mainPanel(
uiOutput("tabs")
)
),
server = function(input, output) {
output$tabs <- renderUI({
tables <- lapply( list("dt1", "dt2", "dt3"), function(x){

DT::dataTableOutput( x )
})
tagList(tables)
})

lapply( list("dt1", "dt2", "dt3"), function(x) {

output[[x]] <- DT::renderDataTable( DT::datatable( data.frame("data") ) )

observeEvent({
input[[paste( x, "rows_selected", sep="_" )]]
},{
print( paste( x, ":", input[[paste( x, "rows_selected", sep="_" )]] ) )
})

})
}
)

Regards,
Yihui

> --
> You received this message because you are subscribed to the Google Groups
> "Shiny - Web Framework for R" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to shiny-discus...@googlegroups.com.
> To view this discussion on the web visit
> https://groups.google.com/d/msgid/shiny-discuss/a018dcd4-f39a-49dc-92fa-3331eb265cb5%40googlegroups.com.
>
> For more options, visit https://groups.google.com/d/optout.

[Isam Haddad]

But this brings me back to my original problem: list("dt1", "dt2", "dt3") changes dynamically. If I move the lapply over this list to the top level of the server function I'll get:

Error in .getReactiveEnvironment()$currentContext() :
  Operation not allowed without an active reactive context. (You tried to do something that can only be done from inside a reactive expression or observer.)

Any idea how to prevent this else?

[Yihui Xie]

Okay, in that case, I think your original solution makes sense.

Regards,
Yihui