Editable DT on Shiny Server: Edits through coerceValue/replaceData operational, yet forces JSON Error when Server = FALSE passed.

[HitKnit]

Dear DT community.

I have a fully operational Shiny app in which the user edits a DT object, after which some dependent summary statistics are displayed. When passing the client-side processing option to renderDT (server = F) in order to speed things up, a user edit of the DT is implemented correctly with the dependent summary stats updating, however the browser throws the following (dismissable) error;

DataTables warning: table id=DataTables_Table_5 - Invalid JSON response. For more information about this error, please see http://datatables.net/tn/1

I have browsed and posted a thorough query on SO which remains unresolved;
https://stackoverflow.com/questions/52519367/dt-editing-in-shiny-application-with-client-side-processing-server-f-throws

REPRODUCIBLE EXAMPLE (Only allowing edits in Col 1), Note that changing server = TRUE yields fully operational application

library(shiny)
library(DT)

dt = data.frame(V1 = c(1,2), V2 = c(3,4))

server <- function(input, output, session) {
    
val = reactiveValues(mat = data.table(dt))
    
output$testDT = renderDataTable({
            DT::datatable(val$mat, editable = TRUE)
}, server = FALSE)
    
proxy = dataTableProxy('testDT')

observeEvent(input$testDT_cell_edit, {
  
  info = input$testDT_cell_edit
  
  str(info)
  
  i = info$row
  j = info$col
  v = info$val
  
  if (j == 1){
    
  val$mat$V1[i] = DT::coerceValue(v, val$mat$V1[i])
  replaceData(proxy, val$mat, rownames = FALSE)
  
  }
  
})
    
    
}

ui <- fluidPage(
  dataTableOutput('testDT') 
)

shinyApp(ui, server)

[shrektan]

Probably it's not documented clearly. It has nothing to do with the editing. It's because replaceData() calls reloadData(), which requires the server-side processing mode. See ?reloadData().

reloadData() only works for tables in the server-side processing mode, e.g. tables rendered with renderDataTable(server = TRUE). The data to be reloaded (i.e. the one you pass to dataTableAjax()) must have exactly the same number of columns as the previous data object in the table.

[HitKnit]

Probably it's not documented clearly. It has nothing to do with the editing. It's because replaceData() calls reloadData(), which requires the server-side processing mode. See ?reloadData().

reloadData() only works for tables in the server-side processing mode, e.g. tables rendered with renderDataTable(server = TRUE). The data to be reloaded (i.e. the one you pass to dataTableAjax()) must have exactly the same number of columns as the previous data object in the table.

Thank you for your answer. So I suppose at this stage it is not possible to implement an editable DT with client-side processing when replaceData has to be called in that process. Feel free to paste your reply into the SO thread as well and I'll approve it.

[shrektan]

I've pasted the reply on the SO 😺 .

Since the issue has been solved, would you please close this issue?

Thanks.