how to send an numpy array or a pytorch Tensor through http post request using requests module and Flask

Question

I have an image and I want to send it to the serve. I'm using requests module to perform simple post request as following(info is a dictionary):

    import requests

    print(type(info["array_image"]))
    print(type(info["visual_features"]))
    response = requests.post("url", data=info)

output :

<class 'numpy.ndarray'>
<class 'torch.Tensor'>

on the server side I'm trying to receive them as arrays at least:

from flask import Flask, request

@app.route('/path', methods=['POST'])
def function_name():
    visual_features = request.form['visual_features']
    array_image = request.form['array_image']
    print(type(array_image))
    print(type(visual_features))

output:

<class 'str'>
<class 'str'>

I want to get a bytes array to build the image, but what I'm getting is a string... If I didn't find a way I'll encode arrays in bas64 and then decode it in the server...

Hassan Kanso · Accepted Answer · 2022-01-16 11:20:22Z

Thanks to @praba230890 for giving me an easy to follow example.

I would still write the solution here down, since the provided link doesn't fit my case exactly.

import pickle
import io

bytes_image = pickle.dumps(info["array_image"])
stream = io.BytesIO(bytes_image)
files = {"bytes_image": stream}

info["array_image"] = None

response = http.post("url", data=info, files=files)

and in the server side:

from flask import Flask, request

@app.route('/path', methods=['POST'])
def function_name():
    image = request.files.get('bytes_image')
    bytes_image = image.read()

if you want to get the image from a file, then:

requests.post("http://localhost:5000/predict",
                 files={"file": open('<PATH/TO/.jpg/FILE>/cat.jpg','rb')})

The Solution I'm currently using:

remember info["array_image"] is a numpy array, and info is a dictionary

    import io
    info["image_shape_width"] = info["array_image"].shape[0]
    info["image_shape_height"] = info["array_image"].shape[1]

    bytes_image = info["array_image"].tobytes()
    stream = io.BytesIO(bytes_image)
    files = {"bytes_image": stream}

    info["array_image"] = None

    response = http.post(self.ip + "path", data=info, files=files)

then receive it

    from flask import Flask, request
    import numpy as np

    @app.route('/path', methods=['POST'])
    def function_name():    
        bytes_image = request.files.get('bytes_image')
        bytes_image = bytes_image.read()
        array_image = np.frombuffer(bytes_image, dtype=dtype)
        shape = (int(request.form['image_shape_width']), int(request.form['image_shape_height']), 3)         
        array_image = np.reshape(array_image, shape)
                                       
        image = Image.fromarray(array_image)

praba230890 · Accepted Answer · 2021-11-30 19:10:59Z

0

You can try to convert your data to proper JSON or use Python pickle module or if you have an image as you've mentioned you can send it as a file (multipart request) to the server as shown in the examples here.

answered Nov 30, 2021 at 19:10

praba230890

2,32022 silver badges37 bronze badges

1 Comment

Hassan Kanso Over a year ago

this is the half way...it worked, but I'm saving the image in a file then I pass the file to the post request...this is not good because I have to save every image in the storage, I want to pass a file without storing it

Collectives™ on Stack Overflow

how to send an numpy array or a pytorch Tensor through http post request using requests module and Flask

2 Answers 2

The Solution I'm currently using:

Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

The Solution I'm currently using:

Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related