Extract an error message from an object — extract

A convenience function to extract the error message attached to an object. A method is implemented for validated_reactive_val() objects.

Usage

extract_error(x, ..., capture = TRUE)

Arguments

x: (any) The object from which to extract the error message.
...: Additional arguments passed to methods.
capture: (length-1 logical) If TRUE, the error is captured and returned with class captured-error (as well as captured- prepended on any error subclasses). If FALSE, the error is thrown.

Value

If the object contains an error message, an object with class captured-error if capture is TRUE or the error condition if capture is FALSE. Depending on your purpose, you may need to signalCondition() or rlang::cnd_signal() to actually signal the error. If the object does not contain an error, NULL.

Examples

vrv <- validated_reactive_val(
  value = "good",
  default = "default",
  validation_expr = {
    if (.vrv() == "bad") {
      rlang::abort("is bad", class = "special_error")
    }
    .vrv()
  }
)
shiny::isolate(extract_error(vrv))
#> NULL
vrv("bad")
shiny::isolate(vrv())
#> [1] "default"
captured_error <- shiny::isolate(extract_error(vrv))
class(captured_error)
#> [1] "captured-special_error" "captured-rlang_error"   "captured-error"        
#> [4] "captured-condition"    
captured_error$message
#> [1] "is bad"
raw_error <- shiny::isolate(extract_error(vrv, capture = FALSE))
try(rlang::cnd_signal(raw_error))
#> Error : is bad