Hello Jakob, thanks for the reply. I put the code in another TryCatch, but
it has not been caught and there's no error. I am confused. On repeatedly
running the same code more thing once, occasionally I see the required
message.
Please find the updated exception handling code here:
std::string describeException(v8::Isolate *isolate, v8::TryCatch
*try_catch) {
std::ostringstream os;
v8::HandleScope handle_scope(isolate);
v8::TryCatch trycatch(isolate);
v8::String::Utf8Value exception(isolate, try_catch->Exception());
const char *exception_string = ToCString(exception);
auto context = isolate->GetCurrentContext();
v8::Local<v8::Message> message = try_catch->Message();
os << "Exception: ";
os << exception_string;
os << " " << std::endl;
// Print exception location details
if (!message.IsEmpty()) {
// Print location
v8::String::Utf8Value filename(isolate,
message->GetScriptOrigin().ResourceName());
v8::Local<v8::Context> context(isolate->GetCurrentContext());
const char *filename_string = ToCString(filename);
int linenum = message->GetLineNumber(context).FromJust();
os << "Location: " << filename_string << ":" << linenum << " " << std::endl;
// Print source code
// Print line of source code.
os << "Code: " << std::endl;
v8::String::Utf8Value sourceline(
isolate, message->GetSourceLine(context).ToLocalChecked());
const char* sourceline_string = ToCString(sourceline);
os << sourceline_string << std::endl;
// Print stack trace
v8::Local<v8::Value> stack_trace_string;
if (try_catch->StackTrace(context).ToLocal(&stack_trace_string) &&
stack_trace_string->IsString() &&
v8::Local<v8::String>::Cast(stack_trace_string)->Length() > 0) {
v8::String::Utf8Value stack_trace(isolate, stack_trace_string);
const char* stack_trace_string = ToCString(stack_trace);
os << stack_trace_string << std::endl;
}
}
if (trycatch.HasCaught()) {
v8::String::Utf8Value internal_exception(isolate, trycatch.Exception());
const char *internal_exception_string = ToCString(exception);
os << "Internal Error while trying to prepare exception string:" <<
std::endl;
os << internal_exception_string << std::endl;
}
return os.str();
}
I see that the exception messages are randomly blank despite me checking
for try_catch.HasCaught()
On Tuesday, February 9, 2021 at 5:56:31 PM UTC+5:30 Jakob Kummerow wrote:
> The general pattern is that returned MaybeHandles (from any function, not
> just JSON::Stringify) are empty when an exception has been thrown by the
> operation. You can use a v8::TryCatch to catch this exception and inspect
> it, it'll include a helpful error message.
>
>
> On Tue, Feb 9, 2021 at 1:21 PM 'Vinayaka Kamath' via v8-users <
> v8-u...@googlegroups.com> wrote:
>
>> Hello All,
>>
>> A call to JSON::Stringify is returning empty handle. I ensured that the
>> parameters are valid. What are the other possible reasons? I tried
>> retrieving the "JSON" object from the context using context->Global(), that
>> fails and returns empty handle.
>>
>> bool toJSON(v8::Isolate *isolate, const v8::Local<v8::Value> &object,
>> std::string &json) {
>>
>> json.clear();
>>
>> if (object.IsEmpty()) { // Object is not empty
>> return true;
>> }
>>
>> v8::HandleScope handle_scope(isolate);
>> auto context = isolate->GetCurrentContext();
>> std::cout << "Context: " << context.IsEmpty() << "\n";
>> std::cout << "converting to string \n";
>> v8::Local<v8::Value> result;
>> if (!v8::JSON::Stringify(context, object).ToLocal(&result)) //
>> This call is failing
>> return false;
>> json = *v8::String::Utf8Value(isolate, result);
>> std::cout << "done converting to string \n" << json;
>> return true;
>> }
>>
>> Any help would be very much appreciated, thanks!
>>
>> --
>>
>
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