Use the route() decorator is used to bind a function to a URL

[sharoonthomas]

Using a decorator to bind URLs to view functions the canonical way to route URLs in flask. This patch implements the same for nereid and this issue will be used as a reference to why this change is done and the implementation detail.

New design

It is now possible to use a route decorator to bind your URLs to view functions. Example below::

class Product:
    __name__ = 'product.product'

    @classmethod
    @route('/product/<uri>')
    def render_product(cls, uri):
        ...
        return 'Product Information'

Caveats

Methods need to be decorated again if they are implemented in subclasses (mostly in downstream modules). This is easier to explain with an example.

If the code in the above example was from nereid_catalog module and the nereid_webshop module implements this method to make a change in the behavior, then the decorator needs to be applied again.

Example code:

# File: nereid_webshop/product.py

class Product:
    __name__ = 'product.product'

    @classmethod
    @route('/product/<uri>')
    def render_product(cls, uri):
        # Do something here
        # may be call the super function to get the response
        # return the final result
       return render_template('...')

Before

Nereid, until version 3.0.7.0 used xml records which created the rules in the database to bind URLs to view functions which were methods in tryton models. This was required because the URLs (and view functions) change depending on the database (more precisely the modules installed in the database). Since XML records in a module are only created in the database when a module is installed for the specific database, it was an easy way to bind URLs to the corresponding views. However, the approach had its flaws:

1. URL creation was more complicated than it should have been (define XML, upgrade DB and so on).
2. Non flaskish - URL routing with decorators is indeed considered a major feature of Flask and nereid should not miss out on it.

[sharoonthomas]

Implemented