Uploading files via forms and doing it properly is usually a matter of concern for many web frameworks. Flask and WTForms handle this for us in a simple and streamlined manner.
First, we will start with the configuration bit. We need to provide a parameter to our application configuration, that is, UPLOAD_FOLDER. This parameter tells Flask about the location where our uploaded files will be stored. We will implement a feature to store product images.
Tip
One way to store product images can be to store images in a binary type field in our database, but this method is highly inefficient and never recommended in any application. We should always store images and other uploads in the filesystem and store their location in the database using a string field.
Add the following statements to the configuration in my_app/__init__.py:
import os
ALLOWED_EXTENSIONS = set(['txt', 'pdf', 'png', 'jpg', 'jpeg', 'gif'])
app.config['UPLOAD_FOLDER'] = os.path.realpath('....