Backend with Python (Flask).md

Sample Server in Python using the Flask framework

Based on szelcsanyi's example gist:

from flask import Flask, render_template, request, abort, jsonify
import os
app = Flask(__name__)
app.debug = True

temp_base = os.path.expanduser("~/tmp/flask_uploads/")

# landing page
@app.route("/resumable")
def resumable_example():
    return render_template("resumable_upload.html")

# resumable.js uses a GET request to check if it uploaded the file already.
# NOTE: your validation here needs to match whatever you do in the POST (otherwise it will NEVER find the files)
@app.route("/resumable_upload", methods=['GET'])
def resumable():
    resumableIdentfier = request.args.get('resumableIdentifier', type=str)
    resumableFilename = request.args.get('resumableFilename', type=str)
    resumableChunkNumber = request.args.get('resumableChunkNumber', type=int)

    if not resumableIdentfier or not resumableFilename or not resumableChunkNumber:
        # Parameters are missing or invalid
        abort(500, 'Parameter error')

    # chunk folder path based on the parameters
    temp_dir = os.path.join(temp_base, resumableIdentfier)

    # chunk path based on the parameters
    chunk_file = os.path.join(temp_dir, get_chunk_name(resumableFilename, resumableChunkNumber))
    app.logger.debug('Getting chunk: %s', chunk_file)

    if os.path.isfile(chunk_file):
        # Let resumable.js know this chunk already exists
        return 'OK'
    else:
        # Let resumable.js know this chunk does not exists and needs to be uploaded
        abort(404, 'Not found')


# if it didn't already upload, resumable.js sends the file here
@app.route("/resumable_upload", methods=['POST'])
def resumable_post():
    resumableTotalChunks = request.form.get('resumableTotalChunks', type=int)
    resumableChunkNumber = request.form.get('resumableChunkNumber', default=1, type=int)
    resumableFilename = request.form.get('resumableFilename', default='error', type=str)
    resumableIdentfier = request.form.get('resumableIdentifier', default='error', type=str)

    # get the chunk data
    chunk_data = request.files['file']

    # make our temp directory
    temp_dir = os.path.join(temp_base, resumableIdentfier)
    if not os.path.isdir(temp_dir):
        os.makedirs(temp_dir, 0777)

    # save the chunk data
    chunk_name = get_chunk_name(resumableFilename, resumableChunkNumber)
    chunk_file = os.path.join(temp_dir, chunk_name)
    chunk_data.save(chunk_file)
    app.logger.debug('Saved chunk: %s', chunk_file)

    # check if the upload is complete
    chunk_paths = [os.path.join(temp_dir, get_chunk_name(resumableFilename, x)) for x in range(1, resumableTotalChunks+1)]
    upload_complete = all([os.path.exists(p) for p in chunk_paths])

    # combine all the chunks to create the final file
    if upload_complete:
        target_file_name = os.path.join(temp_base, resumableFilename)
        with open(target_file_name, "ab") as target_file:
            for p in chunk_paths:
                stored_chunk_file_name = p
                stored_chunk_file = open(stored_chunk_file_name, 'rb')
                target_file.write(stored_chunk_file.read())
                stored_chunk_file.close()
                os.unlink(stored_chunk_file_name)
        target_file.close()
        os.rmdir(temp_dir)
        app.logger.debug('File saved to: %s', target_file_name)

    return 'OK'


def get_chunk_name(uploaded_filename, chunk_number):
    return uploaded_filename + "_part_%03d" % chunk_number