Url and Page classes used to encapsulate the "site map" information (URL
regular expressions, Django views, menu item names, etc.) and the relation
between pages in the site map.
There are still lots of TODOs in this first pass.
Patch by: Todd Larsen
Review by: to-be-reviewed
"""
Module for abstract serializer/unserializer base classes.
"""
try:
from cStringIO import StringIO
except ImportError:
from StringIO import StringIO
from django.db import models
from django.utils.encoding import smart_str, smart_unicode
class SerializationError(Exception):
"""Something bad happened during serialization."""
pass
class DeserializationError(Exception):
"""Something bad happened during deserialization."""
pass
class Serializer(object):
"""
Abstract serializer base class.
"""
# Indicates if the implemented serializer is only available for
# internal Django use.
internal_use_only = False
def serialize(self, queryset, **options):
"""
Serialize a queryset.
"""
self.options = options
self.stream = options.get("stream", StringIO())
self.selected_fields = options.get("fields")
self.start_serialization()
for obj in queryset:
self.start_object(obj)
for field in obj._meta.fields:
if field.serialize:
if field.rel is None:
if self.selected_fields is None or field.attname in self.selected_fields:
self.handle_field(obj, field)
else:
if self.selected_fields is None or field.attname[:-3] in self.selected_fields:
self.handle_fk_field(obj, field)
for field in obj._meta.many_to_many:
if field.serialize:
if self.selected_fields is None or field.attname in self.selected_fields:
self.handle_m2m_field(obj, field)
self.end_object(obj)
self.end_serialization()
return self.getvalue()
def get_string_value(self, obj, field):
"""
Convert a field's value to a string.
"""
if isinstance(field, models.DateTimeField):
value = getattr(obj, field.name).strftime("%Y-%m-%d %H:%M:%S")
else:
value = field.flatten_data(follow=None, obj=obj).get(field.name, "")
return smart_unicode(value)
def start_serialization(self):
"""
Called when serializing of the queryset starts.
"""
raise NotImplementedError
def end_serialization(self):
"""
Called when serializing of the queryset ends.
"""
pass
def start_object(self, obj):
"""
Called when serializing of an object starts.
"""
raise NotImplementedError
def end_object(self, obj):
"""
Called when serializing of an object ends.
"""
pass
def handle_field(self, obj, field):
"""
Called to handle each individual (non-relational) field on an object.
"""
raise NotImplementedError
def handle_fk_field(self, obj, field):
"""
Called to handle a ForeignKey field.
"""
raise NotImplementedError
def handle_m2m_field(self, obj, field):
"""
Called to handle a ManyToManyField.
"""
raise NotImplementedError
def getvalue(self):
"""
Return the fully serialized queryset (or None if the output stream is
not seekable).
"""
if callable(getattr(self.stream, 'getvalue', None)):
return self.stream.getvalue()
class Deserializer(object):
"""
Abstract base deserializer class.
"""
def __init__(self, stream_or_string, **options):
"""
Init this serializer given a stream or a string
"""
self.options = options
if isinstance(stream_or_string, basestring):
self.stream = StringIO(stream_or_string)
else:
self.stream = stream_or_string
# hack to make sure that the models have all been loaded before
# deserialization starts (otherwise subclass calls to get_model()
# and friends might fail...)
models.get_apps()
def __iter__(self):
return self
def next(self):
"""Iteration iterface -- return the next item in the stream"""
raise NotImplementedError
class DeserializedObject(object):
"""
A deserialized model.
Basically a container for holding the pre-saved deserialized data along
with the many-to-many data saved with the object.
Call ``save()`` to save the object (with the many-to-many data) to the
database; call ``save(save_m2m=False)`` to save just the object fields
(and not touch the many-to-many stuff.)
"""
def __init__(self, obj, m2m_data=None):
self.object = obj
self.m2m_data = m2m_data
def __repr__(self):
return "<DeserializedObject: %s>" % smart_str(self.object)
def save(self, save_m2m=True):
# Call save on the Model baseclass directly. This bypasses any
# model-defined save. The save is also forced to be raw.
# This ensures that the data that is deserialized is literally
# what came from the file, not post-processed by pre_save/save
# methods.
models.Model.save_base(self.object, raw=True)
if self.m2m_data and save_m2m:
for accessor_name, object_list in self.m2m_data.items():
setattr(self.object, accessor_name, object_list)
# prevent a second (possibly accidental) call to save() from saving
# the m2m data twice.
self.m2m_data = None