Hi, this is how I do it, but don't rely on effectiveness of this
solution - I'd be the first one to say that I'm a mediocre programmer
:)
def serialize(data):
'''Input: instance of PluginParameters
Output: base64-encoded string that can be stored in a database
'''
if not isinstance(data, PluginParameters):
error('Attempt to serialize data of unsupported type (%s)' % type(data))
raise TypeError('Cannot serialize data of type %s' % type(data))
# Loop through all attributes, identify any QuerySets
# and use only their 'query' attribute for pickling (disregard the rest)
for attr_name in data.__dict__:
value = getattr(data, attr_name)
if isinstance(value, QuerySet):
setattr(data, attr_name, value.query)
if _compress:
res = b64encode(zlib.compress(pickle.dumps(data)))
else:
res = b64encode(pickle.dumps(data))
debug2('Serialized parameters: %g bytes' % len(res))
return res
def deserialize(data):
'''process base64 encoded pickled object
and return an instance of PluginParameters
'''
debug2('Deserializing parameters: %g bytes' % len(data))
if _compress:
res = pickle.loads(zlib.decompress(b64decode(data)))
else:
res = pickle.loads(b64decode(data))
# identify any 'query' object and reconstruct the original QuerySet
for attr_name in res.__dict__:
value = getattr(res, attr_name)
if isinstance(value, Query):
# the black magic starts here ;-)
model = value.model # get the original model owning the query
qs = model.objects.all() # create a QuerySet based on that model
qs.query = value # reattach the orignal 'query' to the QuerySet
setattr(res, attr_name, qs) # and inject this back to the
# PluginParameters object
return res
Hope this helps
Jirka
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