Flask to return image stored in database

Question

My images are stored in a MongoDB, and I'd like to return them to the client, here is how the code is like:

@app.route("/images/<int:pid>.jpg")
def getImage(pid):
    # get image binary from MongoDB, which is bson.Binary type
    return image_binary

However, it seems that I can't return binary directly in Flask? My idea so far:

1. Return the base64 of the image binary. The problem is that IE<8 doesn't support this.
2. Create a temporary file then return it with send_file.

Are there better solutions?

Answer 1

Create a response object with the data and then set the content type header. Set the content disposition header to attachment if you want the browser to save the file instead of displaying it.

@app.route('/images/<int:pid>.jpg')
def get_image(pid):
    image_binary = read_image(pid)
    response = make_response(image_binary)
    response.headers.set('Content-Type', 'image/jpeg')
    response.headers.set(
        'Content-Disposition', 'attachment', filename='%s.jpg' % pid)
    return response

Relevant: werkzeug.Headers and flask.Response

You can pass a file-like object and the header arguments to send_file to let it set up the complete response. Use io.BytesIO for binary data:

return send_file(
    io.BytesIO(image_binary),
    mimetype='image/jpeg',
    as_attachment=True,
    download_name='%s.jpg' % pid)

Prior to Flask 2.0, download_name was called attachment_filename.

Answer 2

Just wanted to confirm that dav1d's second suggestion is correct - I tested this (where obj.logo is a mongoengine ImageField), works fine for me:

import io

from flask import current_app as app
from flask import send_file

from myproject import Obj

@app.route('/logo.png')
def logo():
    """Serves the logo image."""

    obj = Obj.objects.get(title='Logo')

    return send_file(
        io.BytesIO(obj.logo.read()),
        download_name='logo.png',
        mimetype='image/png'
    )

Easier than manually creating a Response object and settings its headers.

_{Prior to Flask 2.0, download_name was called attachment_filename.}

Answer 3

Suppose i have the stored image path with me. The below code helps to send image through.

from flask import send_file
@app.route('/get_image')
def get_image():
    filename = 'uploads\\123.jpg'
    return send_file(filename, mimetype='image/jpg')

uploads is my folder name where my image with 123.jpg is present.

[PS: The uploads folder should be in the current directory as of the your script file]

Hope it helps.

Answer 4

The following worked for me (for Python 3.7.3):

import io
import base64
# import flask
from PIL import Image

def get_encoded_img(image_path):
    img = Image.open(image_path, mode='r')
    img_byte_arr = io.BytesIO()
    img.save(img_byte_arr, format='PNG')
    my_encoded_img = base64.encodebytes(img_byte_arr.getvalue()).decode('ascii')
    return my_encoded_img

...
# your api code
...
img_path = 'assets/test.png'
img = get_encoded_img(img_path)
# prepare the response: data
response_data = {"key1": value1, "key2": value2, "image": img}
# return flask.jsonify(response_data )