SqlAlchemy Adapter

Hi,

I've been playing with the SQLAlchemy adapter, but I found that it was lacking
in a couple of ways. I coded my own, and it passes the tests. Here's the code:
what do you think?



"""
SQLAlchemy adapter (experimental!)

By Dave Thompson

@since: 0.4.0
"""
import sqlalchemy

import pyamf

sa_properties = ('_state', '_sa_instance_state', '_sa_class_manager')

def get_SA_attrs(obj):
    """Get attributes to be encoded for a SA object."""
    if not is_SA_object(obj):
        return pyamf.util.native_get_attrs(obj)

    attrs = {}
    for property in obj.__dict__:
        if property in sa_properties:
            continue

        if property.startswith('__'):
            continue

        attrs[property] = getattr(obj, property)
    return attrs

def write_SA_collection(obj):
    """Convert a SQLAlchemy collection to a native type."""
    if isinstance(obj, sqlalchemy.orm.collections.InstrumentedList):
        new_obj = []
        new_obj.extend(obj)
        return new_obj
    if isinstance(obj, sqlalchemy.orm.collections.InstrumentedDict):
        new_obj = {}
        new_obj.update(obj)
        return new_obj
    if isinstance(obj, sqlalchemy.orm.collections.InstrumentedSet):
        new_obj = Set()
        new_obj.union(obj)
        return new_obj

    raise "Not a known SQLAlchemy collection type."

def is_SA_object(obj):
    """Detect if this object is a SQLAlchemy instance."""
    if is_SA_collection(obj):
        return False

    for property in sa_properties:
        if hasattr(obj, property):
            return True

    return False

def is_SA_collection(obj):
    """Detect if this object is a SQLAlchemy collection."""
    if isinstance(obj, sqlalchemy.orm.collections.InstrumentedList):
        return True
    if isinstance(obj, sqlalchemy.orm.collections.InstrumentedSet):
        return True
    if isinstance(obj, sqlalchemy.orm.collections.InstrumentedDict):
        return True
    return False

# Replace this method with the adapter's
pyamf.util.native_get_attrs = pyamf.util.get_attrs
pyamf.util.get_attrs = get_SA_attrs
# turn collections into native objects
pyamf.add_type(is_SA_collection, write_SA_collection)

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