SQLAlchemy提交泡菜类型

Question

I'm having an issue committing changes to pickle types (lists) in sqlalchemy. It will act as if nothing happened after the committal.

Here's my my function where I try to commit:

def commit_move(game_id, player, move):
    game = game_query(game_id)
    if player == 'human':
        game.human_spaces.append(move)
    if player == 'ai':
        game.ai_spaces.append(move)
    game.available_spaces.remove(move)
    print game.human_spaces
    print game.ai_spaces
    print game.available_spaces
    print "----"
    session.add(game)
    session.commit()

here's how the table is setup:

class Game(Base):
    __tablename__ = 'game'
    id = Column(Integer, primary_key=True)
    human_spaces = Column(PickleType)
    ai_spaces = Column(PickleType)
    available_spaces = Column(PickleType)

here's the code I'm using to test it:

game_id = create_game()
print game_id
print get_available_spaces(game_id)
print get_human_spaces(game_id)
print get_ai_spaces(game_id)
print "---------"
commit_move(game_id, 'human', 7)
print get_available_spaces(game_id)
print get_human_spaces(game_id)
print get_ai_spaces(game_id)

and here's what the good ol' terminal is telling me:

1
[1, 2, 3, 4, 5, 6, 7, 8, 9]
[]
[]
---------
[7]
[]
[1, 2, 3, 4, 5, 6, 8, 9]
----
[1, 2, 3, 4, 5, 6, 7, 8, 9]
[]
[]

I'm sure it's something simple I'm missing here, but any help would be greatly appreciated!

Answer 1

The problem is that the ORM is not alerted to changes inside a mutable type, like a list. SQLAlchemy therefore offers mutation tracking with the sqlalchemy.ext.mutable extension.

From the examples in the documentation , in particular with reference to the sqlalchemy.ext.mutable.MutableList class, it looks like the column declaration should go (eg):

human_spaces = Column(MutableList.as_mutable(PickleType))

I quote from the documentation on the as_mutable method: "This establishes listeners that will detect ORM mappings against the given type, adding mutation event trackers to those mappings."

Answer 2

I've written a package to help make this easy. You can choose different encodings, including pickle , and easily dump and store objects to a database. It can connect to any database that sqlalchemy understands. There is a dictionary interface to a SQL table, and you can store any type that dill can serialize:

>>> import klepto
>>> db = klepto.archives.sqltable_archive('playgame')
>>> db['human'] = [1,2,3,4]
>>> db['ai'] = [1,2]
>>> db
sqltable_archive('sqlite:///:memory:?table=playgame', {'ai': [1, 2], 'human': [1, 2, 3, 4]}, cached=True)
>>> db.dump()
>>>