How to make verification of files uploaded to the server on flask?

Question

Flask

Hello! Since 2018 everyone!) There was a question, how to check for a flask file? I need to check that the file is png and if it is not, fulfill one condition and stop the program, and also make a check that the image size should be 240 by 250 pixels and again, if not, return an error.

Now I have the following code:

import os
from flask import Flask, request, redirect, url_for
from werkzeug.utils import secure_filename

UPLOAD_FOLDER = '/var/www/html/sample0/files'
ALLOWED_EXTENSIONS = set(['txt', 'pdf', 'png', 'jpg', 'jpeg', 'gif'])

app = Flask(__name__)
app.config['UPLOAD_FOLDER'] = UPLOAD_FOLDER


def allowed_file(filename):
    return '.' in filename and \
           filename.rsplit('.', 1)[1] in ALLOWED_EXTENSIONS

@app.route('/', methods=['GET', 'POST'])
def upload_file():
    if request.method == 'POST':
        file = request.files['file']
        if file and allowed_file(file.filename):
            filename = file.filename#secure_filename(file.filename)
            file.save(os.path.join(app.config['UPLOAD_FOLDER'], filename))
            return '''
            	<script src="https://code.jquery.com/jquery-1.11.3.js"></script>
      	    <script>
      	    $.ajax({
                  url : 'http://mysait.com/sample0/upload.php',
                  success : function(data) {
                    document.body.innerHTML = data;
                }
            });
            </script>
            '''

    return '''
    <script src="https://code.jquery.com/jquery-1.11.3.js"></script>
      <script>
      $.ajax({
          url : 'http://mysait.com/sample0/upload.php',
          success : function(data) {
            document.body.innerHTML = data;
        }
    });
    </script>

    '''

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

As I understand it, only png should be left in ALLOWED_EXTENTION? Thank you in advance!

Answer 1

Here you are right, you need to leave only png in AllowedExtensions , if you only need PNG images, it's logical .

Answer 2

When uploading via HTTP POST, the content_type (Mime type) will be received. Need to check if "image/png" is.
As for the rest: as Mikhail Oleinikov answered .