def default(self, obj):
'''
Converts an object and returns a ``JSON``-friendly structure.
:param obj: object or structure to be converted into a
``JSON``-ifiable structure
Considers the following special cases in order:
* object has a callable __json__() attribute defined
returns the result of the call to __json__()
* date and datetime objects
returns the object cast to str
* Decimal objects
returns the object cast to float
* SQLAlchemy objects
returns a copy of the object.__dict__ with internal SQLAlchemy
parameters removed
* SQLAlchemy ResultProxy objects
Casts the iterable ResultProxy into a list of tuples containing
the entire resultset data, returns the list in a dictionary
along with the resultset "row" count.
.. note:: {'count': 5, 'rows': [('Ed Jones',), ('Pete Jones',),
('Wendy Williams',), ('Mary Contrary',), ('Fred Smith',)]}
* SQLAlchemy RowProxy objects
Casts the RowProxy cursor object into a dictionary, probably
losing its ordered dictionary behavior in the process but
making it JSON-friendly.
* webob_dicts objects
returns webob_dicts.mixed() dictionary, which is guaranteed
to be JSON-friendly.
'''
if hasattr(obj, '__json__') and six.callable(obj.__json__):
return obj.__json__()
elif isinstance(obj, (date, datetime)):
return str(obj)
elif isinstance(obj, Decimal):
# XXX What to do about JSONEncoder crappy handling of Decimals?
# SimpleJSON has better Decimal encoding than the std lib
# but only in recent versions
return float(obj)
elif is_saobject(obj):
props = {}
for key in obj.__dict__:
if not key.startswith('_sa_'):
props[key] = getattr(obj, key)
return props
elif isinstance(obj, ResultProxy):
props = dict(rows=list(obj), count=obj.rowcount)
if props['count'] < 0:
props['count'] = len(props['rows'])
return props
elif isinstance(obj, RowProxy):
return dict(obj)
elif isinstance(obj, webob_dicts):
return obj.mixed()
else:
return JSONEncoder.default(self, obj)
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