Preserving scroll client side

[andrewjmc]

I am having trouble preserving scroll position in unpaged client-side DT in Shiny. In my real application, the data is a reactiveVal created in the global context and shared across users of a multi-user application. Updates can come from a user's own edits or other users.

When coding my app, I was unaware of the dataTableProxy approach.

A minimal example is below. With my approach updating the reactive global data frame, the scroll position is not preserved (clearly I am forcing a refresh of the entire table). The dataTableProxy approach also doesn't work with the client side table, and I get an "invalid JSON response" error.

If, for whatever reason, the out-of-the-box functionality doesn't work for my case, I'd be keen to understand the client-side events I might utilise to cache the current scroll position, and to catch a table redraw and scroll to the stored position.

Grateful for any advice.

library(DT)
library(shiny)
library(magrittr)

ui <- fillPage(
  DTOutput("table", fill=TRUE, height="100%")
)

data <- data.frame(A=paste("Hello", LETTERS), B=paste("Hello", LETTERS), C=paste("Hello", LETTERS))
data %<>% reactiveVal()

server <- function(input, output){
  
  output$table = renderDT(
    data(), server=FALSE, editable=TRUE, options=list(paging=FALSE), height="100%", fillContainer=TRUE
  )

  #proxy <- dataTableProxy("table")
  
  observeEvent(input$table_cell_clicked, ignoreInit=TRUE, ignoreNULL=TRUE, {
    print("clicked")
    local_data <- isolate(data())
    local_data[1,1] <- paste(local_data[1,1], "Hello")
    data(local_data)
    #alternative approach
    #proxy <- replaceData(proxy, local_data)
  })
}

shinyApp(ui, server)