[FIXED] Return an image taken from an URL without storing the image file

Issue

I have an endpoint which downloads an image from an URL, stores it in the project directory and returns the image on the web page. But I don't want the image to be stored in my project directory. is there a way? if not, is there a way to remove the image after the method is executed?

@app.route('/get_image', methods=['GET'])
def get_image():

    r = requests.get("Certain URL")
    file = open("sample.png", "wb")
    file.write(r.content)
    file.close()
    
    return send_file("sample.png", mimetype='image/gif')

Solution

As @TimRoberts said in comment you would have to use io.BytesIO to create file-like object in memory, write in this file and later read from this file.

    r = requests.get("https://placekitten.com/640/360")

    file_like_object = io.BytesIO()
    file_like_object.write(r.content)
    file_like_object.seek(0)  # move to the beginning of file 

    return send_file(file_like_object, mimetype='image/png')

or shorter

    r = requests.get("https://placekitten.com/640/360")

    file_like_object = io.BytesIO(r.content)

    return send_file(file_like_object, mimetype='image/png')

And this can be usefull if you want to generate files instead of getting from server - ie. plot with matplotlib, image with pillow, audio from some TextToSpeech API, etc.

You could find many examples on Stackoverflow.

---

But if you don't want to edit file then there is even simpler method.

Using requests.get(..., stream=True) you may get r.raw which is file-like object.

    r = requests.get("https://placekitten.com/640/360", stream=True)

    file_like_object = r.raw

    return send_file(file_like_object, mimetype='image/png')

---

Minimal working code with both versions, and with real URL so everyone can copy and run it:

EDIT: I added example which resize image without saving on disk.

from flask import Flask, render_template_string, send_file
import requests
import io
from PIL import Image

app = Flask(__name__)

@app.route('/')
def index():
    return render_template_string('''
<img src="/get_image">get_image<br/>
<img src="/get_image_bytesio">get_image_bytesio<br/>
<img src="/get_image_bytesio_smaller">get_image_bytesio_smaller<br/>
''')

@app.route('/get_image')
def get_image():
    r = requests.get("https://placekitten.com/640/360", stream=True)  # it needs `stream=True`
    
    file_like_object = r.raw
    
    return send_file(file_like_object, mimetype='image/png')

@app.route('/get_image_bytesio')
def get_image_bytesio():
    r = requests.get("https://placebear.com/640/360")
    
    #file_like_object = io.BytesIO()
    #file_like_object.write(r.content)
    #file_like_object.seek(0)  # move to the beginning of file after writing

    file_like_object = io.BytesIO(r.content)

    return send_file(file_like_object, mimetype='image/png')

@app.route('/get_image_bytesio_smaller')
def get_image_bytesio_smaller():
    r = requests.get("https://placebear.com/640/360")
    
    file_like_object = io.BytesIO(r.content)

    # edit image without saving on disk    
    img = Image.open(file_like_object)
    img = img.resize((320, 180))

    # `seek()` has to be after `resize()` because it may use `lazy loading`
    
    file_like_object.seek(0)  # move to the beginning of file after reading
    img.save(file_like_object, 'PNG')
    
    file_like_object.seek(0)  # move to the beginning of file after writing
    
    return send_file(file_like_object, mimetype='image/png')

if __name__ == '__main__':
    #app.debug = True 
    app.run() 

Answered By - furas