In these releases we add support of Python 3.7 and PyPy. Also we changed PonyORM internals significantly in order to add two long-demanded features. The first is hybrid methods and properties. Now it is possible to define one-line method or property in entity class and use it inside declarative queries. This way it is possible to re-use complex expressions between different queries:

class Person(db.Entity):
    first_name = Required(str)
    last_name = Required(str)
    country = Required(str)
    age = Required(int)

    @property
    def full_name(self):
        return self.first_name + self.last_name

    @property
    def is_adult(self):
        return self.age > 18

...

query = select(p for p in Person if p.is_adult)

The second feature is the possibility to base query on a previous query. This way it is possible to construct complex queries gradually. In previous versions of Pony it was possible to add conditions by using query.filter method:

query2 = query.filter(lambda person: person.country == 'USA')

but query.filter function cannot change the result type of query. Now you have full flexibility for making your query:

query3 = select(x.full_name for x in query2 if x.last_name.startswith('A'))

Implementing this two features was not easy, because SQL and Python have different namespace rules, and mapping Python name to SQL aliases is a non-trivial task for complex queries.

Also we added a pony.flask subpackage wich provide integration with Flask, so extensions like Flask-Login can work with Pony.

From now on we will concentrate on migration tool and hopefully release it soon.

Here is the detailed changelog:

Pony ORM Release 0.7.4 (2018-07-23)

Major features

• Hybrid methods and properties added
• Allow to base queries on another queries: select(x.a for x in prev_query if x.b)
• Added support of Python 3.7
• Added support of PyPy
• group_concat() aggregate function added
• pony.flask subpackage added for integration with Flask

Other features

• distinct option added to aggregate functions
• Support of explicit casting to float and bool in queries

Improvements

• Apply @cut_traceback decorator only when pony.MODE is ‘INTERACTIVE’

Bugfixes

• In SQLite3 LIKE is case sensitive now
• #249: Fix incorrect mixin used for Timedelta
• #251: correct dealing with qualified table names
• #301: Fix aggregation over JSON Column
• #306: Support of frozenset constants added
• #308: Fixed an error when assigning JSON attribute value to the same attribute: obj.json_attr = obj.json_attr
• #313: Fix missed retry on exception raised during db_session.__exit__
• #314: Fix AttributeError: ‘NoneType’ object has no attribute ‘seeds’
• #315: Fix attribute lifting for JSON attributes
• #321: Fix KeyError on obj.delete()
• #325: duplicating percentage sign in raw SQL queries without parameters
• #331: Overriding __len__in entity fails
• #336: entity declaration serialization
• #357: reconnect after PostgreSQL server closed the connection unexpectedly
• Fix Python implementation of between() function and rename arguments: between(a, x, y) -> between(x, a, b)
• Fix retry handling: in PostgreSQL and Oracle an error can be raised during commit
• Fix optimistic update checks for composite foreign keys
• Don’t raise OptimisticCheckError if db_session is not optimistic
• Handling incorrect datetime values in MySQL
• Improved ImportError exception messages when MySQLdb, pymysql, psycopg2 or psycopg2cffi driver was not found
• desc() function fixed to allow reverse its effect by calling desc(desc(x))
• __contains__ method should check if objects belong to the same db_session
• Fix pony.MODE detection; mod_wsgi detection according to official doc
• A lot of inner fixes

Pony ORM Release 0.7.5 (2018-07-24)

Bugfixes

• query.where and query.filter method bug introduced in 0.7.4 was fixed