NodeJS stdout python多次打印？

Question

I have a python script that prints JSON and string:

# script.py
print('{"name": "bob", "height": 4, "weight": 145}')
print('hello')
sys.stdout.flush()

A nodejs app calls the python script via child-process . But I'm getting error on the output. How can I process the python output in nodejs?

// nodejs
var process = spawn('python3', ["./script.py", toSend]);
    process.stdout.on('data', function(data) {
      message = JSON.parse(data)
      console.log(message)
})

I'm getting this a SyntaxError: Unexpected token from running this.

Answer 1

In your python script... This line

print('{"name": "bob", "height": 4, "weight": 145}')

should be changed

import json
print(json.dumps({"name": "bob", "height": 4, "weight": 145}))

That will handle and make sure the JSON is formatted correctly, so that the JSON string can be parsed by node (but your current version should be fine). However in this case the real problem is what follows...

You are ending your script with

print('hello')

which means that JSON.parse() is going to try and parse hello as part of the JSON.parse() because you are reading from stdout... hello is not JSON formatted. So JSON.parse() is going to fail. So remove that line as well.

If you have more then one json object to send as you stated in your comments

You can either combine all the data into a single JSON object my_object = {"data": "info"....} and json.dumps() that single larger object..

or

obj1 = {}
obj2 = {}
myobjects = [obj1, obj2]
print(json.dumps(myobjects))

and the Node side will recieve a list of objects that can be iterated on