如何在弹出窗口中显示闪亮错误堆栈跟踪

Question

我想防止我的应用在不可预见的错误时崩溃。当观察者内部发生错误时，就会发生这种情况，因此我创建了自定义观察者函数，该功能通过将错误消息显示为闪亮的弹出窗口来处理错误。但是，我似乎无法获得堆栈跟踪。我看到的每个错误只有光泽内部的调用。

这可能是因为自定义观察者的报价然后eval（）代码。我如何获取一个错误消息，将我指向我编写的代码，甚至可能避免始终相同的闪亮堆栈跟踪？ this这是我到目前为止所拥有的：

library(shiny)
library(shinyjs)


# Pass through silent shiny "errors" (used for skipping observers by req())
# and show popup if it is a "real" error.
handle_errors_except_shiny <- function(error){
  if(inherits(error, "shiny.silent.error")){
    stop(error)
  }else{
    show_error_popup(error)
  }
}

# like shiny::observe(), but display a notification in case of error
safe_observe <- function(x, env = parent.frame(), quoted = FALSE, ..., domain = getDefaultReactiveDomain()){
  if(!quoted){
    x <- substitute(x)
  }
  x <- bquote(tryCatch( .(x),  error = handle_errors_except_shiny ))
  
  observe(x=x, env=env, quoted=TRUE, domain=domain, ...)
}

# Can be used as error handler in tryCatch( error= ... ) within observers to prevent application crash but
# rather show a message
# 
# If the error message has the class "userError", a stack trace is not printed but 
# just the error text
# This allows to use this function to display errors that are meant to guide the user.
show_error_popup <- function(e, top_frame = NULL, bottom_frame = parent.frame()){

  stacktrace <- rlang::trace_back(top = top_frame, bottom = bottom_frame)
  showNotification(conditionMessage(e), type = "error", duration = NULL)

  # Print stack trace but it contains only shiny-internal functions :-(
  print(stacktrace)
}


ui <- fluidPage(
  actionButton("btn", "Click Me")
)

server <- function(input, output, session) {
  safe_observe({
    req(input$btn) # take dependency on button
    handle_button()
  })
}

handle_button <- function(){
  stop("test error")
  message("Button clicked\n")
}

shinyApp(ui, server)

输出没有提及

handle_button

，并且不必要地有助于调试应用程序：

     ▆
  1. ├─base (local) `<fn>`(x)
  2. └─shiny:::print.shiny.appobj(x)
  3.   └─shiny::runApp(x) at shiny/R/shinyapp.R:565:3
  4.     ├─shiny::..stacktraceoff..(...) at shiny/R/runapp.R:388:3
  5.     ├─shiny::captureStackTraces(...) at shiny/R/runapp.R:388:3
  6.     │ └─promises::with_promise_domain(...) at shiny/R/conditions.R:125:3
  7.     │   └─domain$wrapSync(expr) at promises/R/domains.R:171:3
  8.     │     └─base::withCallingHandlers(expr, error = doCaptureStack) at shiny/R/conditions.R:185:7
  9.     ├─shiny:::..stacktracefloor..(serviceApp()) at shiny/R/runapp.R:391:9
 10.     └─shiny:::serviceApp() at shiny/R/runapp.R:391:9
 11.       └─shiny:::flushReact() at shiny/R/server.R:492:3
 12.         └─.getReactiveEnvironment()$flush() at shiny/R/react.R:200:3
 13.           └─ctx$executeFlushCallbacks() at shiny/R/react.R:180:9
 14.             └─base::lapply(...) at shiny/R/react.R:111:7
 15.               └─shiny (local) FUN(X[[i]], ...)
 16.                 └─shiny (local) flushCallback() at shiny/R/react.R:112:9
 17.                   ├─shiny:::hybrid_chain(...) at shiny/R/reactives.R:1204:9
 18.                   │ └─shiny (local) do() at shiny/R/utils.R:1558:5
 19.                   │   ├─base::tryCatch(...) at shiny/R/utils.R:1518:5
 20.                   │   │ └─base (local) tryCatchList(expr, classes, parentenv, handlers)
 21.                   │   │   └─base (local) tryCatchOne(expr, names, parentenv, handlers[[1L]])
 22.                   │   │     └─base (local) doTryCatch(return(expr), name, parentenv, handler)
 23.                   │   ├─shiny::captureStackTraces(...) at shiny/R/utils.R:1520:9
 24.                   │   │ └─promises::with_promise_domain(...) at shiny/R/conditions.R:125:3
 25.                   │   │   └─domain$wrapSync(expr) at promises/R/domains.R:171:3
 26.                   │   │     └─base::withCallingHandlers(expr, error = doCaptureStack) at shiny/R/conditions.R:185:7
 27.                   │   ├─base::withVisible(force(expr)) at shiny/R/utils.R:1521:11
 28.                   │   └─base::force(expr) at shiny/R/utils.R:1521:11
 29.                   ├─shiny:::shinyCallingHandlers(run()) at shiny/R/reactives.R:1207:15
 30.                   │ ├─base::withCallingHandlers(...) at shiny/R/utils.R:484:3
 31.                   │ └─shiny::captureStackTraces(expr) at shiny/R/utils.R:484:3
 32.                   │   └─promises::with_promise_domain(...) at shiny/R/conditions.R:125:3
 33.                   │     └─domain$wrapSync(expr) at promises/R/domains.R:171:3
 34.                   │       └─base::withCallingHandlers(expr, error = doCaptureStack) at shiny/R/conditions.R:185:7
 35.                   └─shiny (local) run() at shiny/R/utils.R:484:3
 36.                     └─ctx$run(.func) at shiny/R/reactives.R:1234:7
 37.                       ├─promises::with_promise_domain(...) at shiny/R/react.R:54:7
 38.                       │ └─domain$wrapSync(expr) at promises/R/domains.R:171:3
 39.                       ├─shiny::withReactiveDomain(...) at shiny/R/react.R:55:9
 40.                       │ └─promises::with_promise_domain(...) at shiny/R/reactive-domains.R:98:3
 41.                       │   └─domain$wrapSync(expr) at promises/R/domains.R:171:3
 42.                       │     └─base::force(expr) at shiny/R/utils.R:1598:7
 43.                       └─env$runWith(self, func) at shiny/R/react.R:59:11
 44.                         └─shiny (local) contextFunc() at shiny/R/react.R:158:7
 45.                           ├─shiny::..stacktraceon..(`<observer>`(...)) at shiny/R/utils.R:1449:22
 46.                           └─shiny (local) `<observer>`(...) at shiny/R/conditions.R:522:21
 47.                             └─observe() at shiny/R/utils.R:1459:22
 48.                               └─base::tryCatch(...)
 49.                                 └─base (local) tryCatchList(expr, classes, parentenv, handlers)
 50.                                   └─base (local) tryCatchOne(expr, names, parentenv, handlers[[1L]])
 51.                                     └─value[[3L]](cond)

I发现Shiny具有解决此问题的内部功能。通过更改以下功能，您可以获得想要的内容：

Answer 1

这在堆栈跟踪中显示为this。