Shiny DTedit, show or hide insert/new button based on rows_selected status in second DTedit table

Question

I have two DTedit tables which are functionally related

I do not want users to get the Insert/New button in DT#2 when no row is selected in DT#1

I have Table1_Results$rows_selected to test if selection exists (length>0)

I also identified the id of the 'New button' in DT#2 as being Table2_add

But do not succeed to make the length of Table1_Results$rows_selected trigger the shinyjs show() or hide() action for DT#2

Could anyone please share some reactivity command to do this!

the following code is not working but illustrates my aim

observe(Table1_Results$rows_selected,{
    if (length(Table1_Results$rows_selected)) {
        shinyjs::show('Table2_add')
    } else {
        shinyjs::hide('Table2_add')
    }
})

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.)

This manual test using a button works

observeEvent(input$showhide, {
    toggle('Table2_add')
})

So it is really the reactive testing of the Table1_Results$rows_selected which is lacking

Thanks in advance

---

In the code below:

• I cannot clear the selected row in the observed textoutput
• I do not succeed to hide the New button

Note: I use DTedit because it allows other features not shown here

AIMs: 
1) when no drink is selected, hide the New button for containers
2) manage <table>$rows_selected so that it reflects the current status

library("shiny")
library("shinyjs")
library("DT")
library("DTedit")

server <- function(input, output) {
    
    Drink_Results <- dtedit(
        input, output,
        name = 'Drink',
        thedata = data.frame(
            ID = c(1:3),
            drink = c('Tea', 'Coffea', 'Water'),
            stringsAsFactors = FALSE
        )
    )

    # create proxy to clear row selection (found 'Drinkdt' by looking in the source)
    Drink_proxy <- DT::dataTableProxy('Drinkdt')
    
    Container_Results <- dtedit(
        input, output,
        name = 'Container',
        thedata = data.frame(
            ID = c(1:3),
            Container = c('Cup', 'Glass', 'Pint'),
            stringsAsFactors = FALSE
        )
    )

    # create proxy to clear row selection    
    Container_proxy <- DT::dataTableProxy('Container')

    # manually toggle visibility for New button
    observeEvent(input$showhide, {
        shinyjs::toggle('Container_add')
    })
    
    # clear Drink row selection 
    observeEvent(input$clearrows, {
        Drink_proxy %>% selectRows(NULL)
    })

    # when no drink is selected, hide the New button for containers    
    observeEvent(Drink_Results$rows_selected, {
        if ( length(Drink_Results$rows_selected) ) {
            shinyjs::show('Container_add')
        } else {
            shinyjs::hide('Container_add')
        }
    })
    
    # attempt to react on clearing the row-selection
    choice <- reactive({
        paste0(Drink_Results$rows_selected, " - ", Container_Results$rows_selected)
    })
    
    # output current combination
    output$choice <- renderText({ as.character(choice()) })
    
}

ui <-  tagList(useShinyjs(),
               fluidPage(
                   shinyFeedback::useShinyFeedback(),
                   
                   h3('What will you drink?'),
                   uiOutput('Drink'),
                   
                   # manually clear row selections
                   actionButton(inputId="clearrows", label="clear selected drink", icon=icon('trash')),
                   
                   hr(),
                   
                   h3("What container do you prefer?"),
                   uiOutput('Container'),
                   
                   hr(),
                   
                   # manually hide the New button
                   actionButton(inputId="showhide", label="toggle New buttons", icon=icon('refresh')),
                   
                   hr(),
                   
                   # show current user choices
                   textOutput('choice'),
                   
               )
)

shinyApp(ui = ui, server = server)

Answer 1

The reactive for selected row is input$Drinkdt_rows_selected in your case, based on the source code. If you use that, your code works fine. Try this

server <- function(input, output) {
  
  ##  could not install DTedit. So, made a copy of the function
  source("C:\\RStuff\\GWS\\dtedit.R", local=TRUE)

  Drink_Results <- dtedit(
    input, output,
    name = 'Drink',
    thedata = data.frame(
      ID = c(1:3),
      drink = c('Tea', 'Coffea', 'Water'),
      stringsAsFactors = FALSE
    )
  )
  name <- "Drink"

  # create proxy to clear row selection (found Drinkdt by looking in the source)
  Drink_proxy <- DT::dataTableProxy('Drinkdt')

  Container_Results <- dtedit(
    input, output,
    name = 'Container',
    thedata = data.frame(
      ID = c(1:3),
      Container = c('Cup', 'Glass', 'Pint'),
      stringsAsFactors = FALSE
    )
  )

  # create proxy to clear row selection
  Container_proxy <- DT::dataTableProxy('Container')

  # clear Drink row selection
  observeEvent(input$clearrows, {
    Drink_proxy %>% selectRows(NULL)
    shinyjs::hide('Container_add')
  })
  
  sel <- reactive({!is.null(input[[paste0(name, 'dt_rows_selected')]])}) 
  observe({
    print(sel())
    print(input$Drinkdt_rows_selected)
  })

  # when no drink is selected, hide the New button for containers
  observe({
  #observeEvent(input[[paste0(name, 'dt_rows_selected')]], {
    if ( length(input[[paste0(name, 'dt_rows_selected')]])>0 ) {
      shinyjs::show('Container_add')
    }else {
      shinyjs::hide('Container_add')
    }
  })
  
  observeEvent(Drink_Results$thedata, {
    message(Drink_Results$thedata)
  })

  observeEvent(input[[paste0(name, 'dt_rows_selected')]], ignoreNULL = FALSE, {
    # 'no' (NULL) row will be 'selected' after each edit of the data
    message(paste("Selected row:", input[[paste0(name, 'dt_rows_selected')]]))
  })


  # attempt to react on clearing the row-selection
  choice <- reactive({
    if (is.null(input[[paste0(name, 'dt_rows_selected')]])) {
      paste0("Drink not selected")
    }else {
      paste0(input[[paste0(name, 'dt_rows_selected')]], " - ", input$Containerdt_rows_selected)
    }
    
  })

  observeEvent(input$showhide, {
    toggle('Container_add')
  })
  
  # output current combination
  output$choice <- renderText({ choice() })
}

ui <- fluidPage(
  shinyFeedback::useShinyFeedback(),
  useShinyjs(),
  h3('What will you drink?'),
  uiOutput('Drink'),

  # manually clear row selections
  actionButton(inputId="clearrows", label="clear selected drink", icon=icon('trash')),

  hr(),

  h3("What container do you prefer?"),
  uiOutput('Container'),

  hr(),

  # manually hide the New button
  actionButton(inputId="showhide", label="toggle New buttons", icon=icon('refresh')),

  hr(),

  # show current user choices
  textOutput('choice'),

)

shinyApp(ui = ui, server = server)

Answer 2

btw - it should be mentioned that the original code was not using the jbryer version of DTedit (v1.0.0) , which does not return $rows_selected. The modified DavidPatShuiFong version of DTedit (v 2.2.3+) does return $rows_selected.

The original code presented above used an observeEvent which, by default, has ignoreNULL = TRUE. That doesn't work, because if no row is selected, then $rows_selected will return NULL.

One option is to set ignoreNULL = FALSE. Unfortunately, this still leaves the problem that shinyjs::hide does not work on first execute, perhaps because 'Container_add' does not yet exist on first pass. Adding an invalidateLater which only executes a few times fixes that problem.

library("shiny")
library("shinyjs")
library("DT")
library("DTedit")

server <- function(input, output, session) {
    
    Drink_Results <- dtedit(
        input, output,
        name = 'Drink',
        thedata = data.frame(
            ID = c(1:3),
            drink = c('Tea', 'Coffea', 'Water'),
            stringsAsFactors = FALSE
        )
    )
    
    # create proxy to clear row selection (found 'Drinkdt' by looking in the source)
    Drink_proxy <- DT::dataTableProxy('Drinkdt')
    
    Container_Results <- dtedit(
        input, output,
        name = 'Container',
        thedata = data.frame(
            ID = c(1:3),
            Container = c('Cup', 'Glass', 'Pint'),
            stringsAsFactors = FALSE
        )
    )
    
    # create proxy to clear row selection    
    Container_proxy <- DT::dataTableProxy('Container')
    
    # manually toggle visibility for New button
    observeEvent(input$showhide, {
        shinyjs::toggle('Container_add')
    })
    
    # clear Drink row selection 
    observeEvent(input$clearrows, ignoreNULL = FALSE, {
        Drink_proxy %>% selectRows(NULL)
        shinyjs::hide('Container_add')
    })
    
    # when no drink is selected, hide the New button for containers
    invalidateCount <- reactiveVal(0)
    observe({
        # need to execute this observe more than once
        # (?because 'Container_add' does not actually exist first time?)
        if (isolate(invalidateCount()) < 1) {
            shiny::invalidateLater(200, session) # 200ms delay
        }
        isolate(invalidateCount(invalidateCount() + 1))

        print(paste0("row selected:", Drink_Results$rows_selected))
        if (!is.null(Drink_Results$rows_selected)) {
            shinyjs::show('Container_add')
        } else {
            shinyjs::hide('Container_add')
        }
    })
        
}

ui <-  tagList(useShinyjs(),
    fluidPage(

        h3('What will you drink?'),
        uiOutput('Drink'),
        
        # manually clear row selections
        actionButton(inputId="clearrows", label="clear selected drink", icon=icon('trash')),
        
        hr(),
        
        h3("What container do you prefer?"),
        uiOutput('Container'),
        
        hr(),
        
        # manually hide the New button
        actionButton(inputId="showhide", label="toggle New buttons", icon=icon('refresh')),
        
        hr(),
        
        # show current user choices
        textOutput('choice'),
        
    )
)

shinyApp(ui = ui, server = server)