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Uncaught error when parsing JSON #40
Description
I'm calling a python script that outputs JSON if everything goes right, but outputs an error message otherwise. When using {mode: 'json'}, a JSON parsing error is thrown instead of being returned through the callback.
SyntaxError: Unexpected token o
at Object.parse (native)
at asJson (...\node_modules\python-shell\index.js:142:21)
at ...\node_modules\python-shell\index.js:232:35
at Array.forEach (native)
at PythonShell.receive (...\node_modules\python-shell\index.js:231:11)
at emitOne (events.js:77:13)
at Socket.emit (events.js:169:7)
at readableAddChunk (_stream_readable.js:153:18)
at Socket.Readable.push (_stream_readable.js:111:10)
at Pipe.onread (net.js:531:20)
Activity
extrabacon commentedon Apr 29, 2016
It means non-JSON content got written to stdout, which python-shell tried to parse as JSON. In JSON mode, all output should be JSON-encoded, with carriage returns for separating messages.
DieterDePaepe commentedon Apr 30, 2016
Yes, I know the cause. But the fact that the program didn't output JSON should be seen as an error in my opinion.
extrabacon commentedon May 1, 2016
Right, it should be handled better. I'll keep that in mind for a future version.
zoeesilcock commentedon Oct 11, 2019
I had this issue which was slowing down my development and figured out that I could use stderrParser to transform the errors to valid JSON. By doing this I got the errors come out as messages and can be caught using the
pyshell.on('message', ...)andpyshell.end(...)callbacks.Workaround:
This works for now, but it seems strange that this is needed. Shouldn't python-shell do this internally? As it is now it feels like using
mode: 'json'is broken.Stringify stderr output
Stringify stderr output