I think we can add db.entities and entity._adict_ to documentation. But the suggested text needs to be rephrased. db.entities is a dict and not a list, it maps entity name to entity class. entity._adict_ maps attribute name to attribute descriptor object. It has nothing to do with table or column names. It is often more convenient to use entity._attrs_ list instead of entity._adict_ mapping. entity._attrs_ is a list of all attribute descriptors listed in a declaration order. In order to get table name someone can access entity._table_ property, its value can be a string or a tuple if table name includes schema name as well. The column name can be retrieved from attribute descriptor using attr.column property. Some attributes map to multiple columns, so it is better to use attr.columns property, which returns list of all columns for given attribute. With this changes, the example code will look as: for entity_name, entity_class in db.entities.items(): print(entity_name, entity_class._table_) for attr in entity_class._attrs_: print(attr.name, attr.columns)

If you use JSON column, you can access individual properties to do analytic queries, I think. The example below is for SQLite, but it should work with PostgreSQL as well from pony.orm import * db = Database('sqlite', ':memory:') class X(db.Entity): id = PrimaryKey(int, auto=True) data = Required(Json) set_sql_debug(True) db.generate_mapping(create_tables=True) with db_session: x1 = X(id=1, data={'foo':10, 'bar': 20}) x2 = X(id=2, data={'foo':30, 'bar': 40}) with db_session: query = select(max(int(x.data['foo'])) for x in X if x.data['bar'] > 30) print(query.get()) Maybe we need to add explicit casting to some specific types like float to make it fully universal

You can message traceback directly to me, if you want

At this moment Pony does not support nested tables as a query result. Not all databases allow them. I think it is not necessary to calculate all these information inside a single query, it can be split to two different query with roughly the same total performance. So, instead of: products = select( (p, count(p.reviews), select( (r.review_rating, models.count()) for r in models.Review if r.product == p)) for p in ReviewProduct if JOIN(User[1] in p.users)) You can write two queries, convert them to dict in Python and then combine these dicts if you wish to do it: query1 = select( (p, count(p.reviews)) for p in ReviewProduct if JOIN(User[1] in p.users) ) review_counts = { product: review_count for product, review_count in query1 } query2 = select( (r.product, r.review_rating, models.count()) for r in Review if JOIN(User[1] in r.product.users)) rating_counts = defaultdict(dict) for product, review_raiting, review_count in query2: rating_counts[product][review_raiting] = review_count

Hello im having problems with sqlite: TransactionIntegrityError: Object Autodelete[new:92] cannot be stored in the database. IntegrityError: FOREIGN KEY constraint failed

Hello im having problems with sqlite: TransactionIntegrityError: Object Autodelete[new:92] cannot be stored in the database. IntegrityError: FOREIGN KEY constraint failed

Why that?

Also, when someone post a link to github repository, typically it is not for specific commit, so when a bot post a message after each link it looks a bit like a spam

Here you can find more examples: https://github.com/ponyorm/pony/blob/orm/pony/orm/examples/estore.py https://github.com/ponyorm/pony/blob/orm/pony/orm/examples/university1.py