How to upload multiple files with python flask¶

To upload multiple files, both frontend and backend are involved.

Frontend html¶

Aussume that the url /upload handles uploading.

<form method="post" action="/upload" enctype="multipart/form-data">
    <input multiple id="file" type="file" name="files"/>
    <input type="submit"/>
</form>

Things you should notice about the html form above:

• enctype attribute of form must be multipart/form-data.
• The file input element must have a multiple attribute so that multiple files can be uploaded in one time.

Backend flask¶

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

@app.route('/upload', methods=('POST',))
def upload():
    files = request.files.getlist('files')
    for file in files:
        fn = secure_filename(file.filename)
        file.save(os.path.join(FILES_DIR, fn))  # replace FILES_DIR with your own directory
    return redirect('/')  # change to redirect to your own url

Things you should notice about the flask code above:

• methods must include POST
• To get files, you must use request.files.getlist('files') instead of request.files['files'], because the latter is only used when uploading a single file.
• use secure_filename to prevent malicious file name.

Drag and Drop to upload¶

Please refer to Upload multiple files using "drag and drop" with html5 and flask.