SQLAlchemy Column to Row Transformation and vice versa — is it possible?

Question

I\'m looking for a SQLAlchemy only solution for converting a dict received from a form submission into a series of rows in the database, one for each field submitted. This

Answer 1

Here is a slightly modified example from documentation to work with such table structure mapped to dictionary in model:

from sqlalchemy import *
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm.collections import attribute_mapped_collection
from sqlalchemy.ext.associationproxy import association_proxy
from sqlalchemy.orm import relation, sessionmaker

metadata  = MetaData()
Base = declarative_base(metadata=metadata, name='Base')

class Item(Base):

    __tablename__ = 'Item'
    UniqueId = Column(Integer, ForeignKey('ItemSet.UniqueId'),
                      primary_key=True)
    ItemSet = relation('ItemSet')
    ItemName = Column(String(10), primary_key=True)
    ItemValue = Column(Text) # Use PickleType?

def _create_item(ItemName, ItemValue):
    return Item(ItemName=ItemName, ItemValue=ItemValue)

class ItemSet(Base):

    __tablename__ = 'ItemSet'
    UniqueId = Column(Integer, primary_key=True)
    _items = relation(Item,
                      collection_class=attribute_mapped_collection('ItemName'))
    items = association_proxy('_items', 'ItemValue', creator=_create_item)

engine = create_engine('sqlite://', echo=True)
metadata.create_all(engine)

session = sessionmaker(bind=engine)()
data = {"UniqueId": 1, "a": 23, "b": "Hello", "c": "World"}
s = ItemSet(UniqueId=data.pop("UniqueId"))
s.items = data
session.add(s)
session.commit()