[FIXED] Post numpy array with json to flask app with requests

Issue

Using Requests, I need to send numpy arrays with json data in a single post to my flask application. How do I do this?

Solution

To convert a numpy array arr to json, it can be serialized while preserving dimension with json.dumps(arr.tolist()). Then on the api side, it can be parsed with np.array(json.loads(arr)).

However, when using the requests json parameter, the dumping and loading is handled for you. So arr.tolist() is all that is required on the client, and np.array(arr) on the api. Full example code below.

Client:

params = {'param0': 'param0', 'param1': 'param1'}
arr = np.random.rand(10, 10)
data = {'params': params, 'arr': arr.tolist()}

response = requests.post(url, json=data)

API:

@app.route('/test', methods=['POST'])
def test():
    data = request.json
    params = data['params']
    arr = np.array(data['arr'])
    print(params, arr.shape)
    return "Success"

Output:

{'param0': 'param0', 'param1': 'param1'} (10, 10)

Note: When either the files or data parameter is being used in requests.post, the json parameter is disabled.

Answered By - Jordan Patterson