backend/app.py

app.py

from flask import Flask, render_template, jsonify, request, send_from_directory
from config import Config
from flask_sqlalchemy import SQLAlchemy
from flask_restful import Resource, Api
from flask_cors import CORS

# https://flask-marshmallow.readthedocs.io/en/latest/
from flask_marshmallow import Marshmallow

from werkzeug.utils import secure_filename
import os


class FileEntry(db.Model):
    id = db.Column("file_id", db.Integer, primary_key=True)
    user_name = db.Column(db.String)
    filepath = db.Column(db.String)

class FileEntrySchema(ma.ModelSchema):
    class Meta:
        model = FileEntry



# if the database does not exist, use db.create_all()
def initialize_database():
    try:
        Todo.query.get(1)
    except:
        db.create_all()
        # put some place holder data
        todo0 = Todo(content="buy food", done=False)
        file_entry_0 = FileEntry(user_name="Tian", filepath='C:')

        # add and then commit to apply changes
        db.session.add(todo0)
        db.session.add(file_entry_0)
        db.session.commit()
        # delete use: db.session.delete(me)


ALLOWED_EXTENSIONS = ["txt", "pdf", "png", "jpg", "jpeg", "gif"]

def allowed_file(filename):
    # string.rsplit(separator, max) Specifies how many splits to do.
    if "." in filename and filename.rsplit(".", 1)[1].lower() in ALLOWED_EXTENSIONS:
        return True
    else:
        return False


class upload_file(Resource):
    def get(self):
        file_entries = FileEntry.query.all()
        file_entries_schema = FileEntrySchema(many=True)
        output = file_entries_schema.dump(file_entries)
        return output
    
    def post(self):
        file = request.files.get('file')
        if file:
            if file.filename == "":
                return {"message": "No file found", "status": "error"}

            elif allowed_file(file.filename) is True:
                # https://werkzeug.palletsprojects.com/en/0.15.x/utils/#werkzeug.utils.secure_filename
                filename = secure_filename(file.filename)
                filename_no_extension = filename.rsplit(".", 1)[0]

                existed_entry = FileEntry.query.filter_by(user_name=filename_no_extension).first()
                if existed_entry is None:
                    file_entry = FileEntry(user_name=filename_no_extension, filepath=os.path.join(app.config["UPLOAD_FOLDER"], filename))
                    db.session.add(file_entry)
                else:
                    # if the user_name  already exist, remove the existing file and update the db entry
                    os.remove(existed_entry.filepath)
                    existed_entry.filepath = os.path.join(app.config["UPLOAD_FOLDER"], filename)
                db.session.commit()
                
                file.save(os.path.join(app.config["UPLOAD_FOLDER"], filename))

                return {
                    "filename": filename,
                    "message": "file uploaded",
                    "status": "success",
                }

        # same api can accept other arguments for file system modification, using json to communicate
        file_upload_args = request.get_json()
        print(file_upload_args)

        if "cancel_upload" in file_upload_args:
            filename = file_upload_args["cancel_file"]
            filename = secure_filename(file.filename)
            filename_no_extension = filename.rsplit(".", 1)[0]
            existed_entry = FileEntry.query.filter_by(user_name=filename_no_extension).first()
            db.session.delete(existed_entry)
            db.session.commit()
            try:
                os.remove(os.path.join(app.config["UPLOAD_FOLDER"], filename))
            except FileNotFoundError:
                print('file is already deleted')


class download_file(Resource):
    # http://flask.pocoo.org/docs/1.0/patterns/fileuploads/
    def get(self):
        return send_from_directory(app.config["UPLOAD_FOLDER"], "alex.jpg", as_attachment=True)


api.add_resource(todo_database_access, "/todo_db")
api.add_resource(upload_file, "/upload_file")
api.add_resource(download_file, "/download_file")