Sending Numpy array to a webhook for Hangouts Chat API with Python?

Question

I've set up a webhook in a chat room in my Google Hangouts Chat.

I can successfully run their example code, which generates a message from the bot associated with the webhook in the chat:

from httplib2 import Http
from json import dumps

#
# Hangouts Chat incoming webhook quickstart
#
def main():
    url = '<INCOMING-WEBHOOK-URL>'
    bot_message = {
        'text' : 'Hello World!'}

    message_headers = { 'Content-Type': 'application/json; charset=UTF-8'}

    http_obj = Http()

    response = http_obj.request(
        uri=url,
        method='POST',
        headers=message_headers,
        body=dumps(bot_message),
    )

    print(response)

if __name__ == '__main__':
    main()

But when I try to sent a Numpy Array with the code:

bot_message = {
            'text' : NumpyArrayObject}

I get the error:

TypeError: Object of type 'ndarray' is not JSON serializable

Using Python list I got the error:

"description": "Invalid JSON payload received. Unknown name \\"text\\" at \'message\': Proto field is not repeating, cannot start list."\n          }\n        ]\n      }\n    ]\n  }\n}\n')

What should I do?

Answer 1

The reason for the error is that a NumPy array is an object, presumably w/a variety of struct/binary/metadata, and can't be directly serialized (converted to a bytestream) that can be saved to JSON format. In order to do so, you need to first convert your array into something that can, using something like ndarray.tolist(). Please see this SO answer for specifics.