django-rest-framework/rest_framework/serializers.py
2013-01-28 22:08:40 +01:00

643 lines
21 KiB
Python

import copy
import datetime
import types
from decimal import Decimal
from django.core.paginator import Page
from django.db import models
from django.forms import widgets
from django.utils.datastructures import SortedDict
from rest_framework.compat import get_concrete_model
# Note: We do the following so that users of the framework can use this style:
#
# example_field = serializers.CharField(...)
#
# This helps keep the seperation between model fields, form fields, and
# serializer fields more explicit.
from rest_framework.relations import *
from rest_framework.fields import *
class DictWithMetadata(dict):
"""
A dict-like object, that can have additional properties attached.
"""
def __getstate__(self):
"""
Used by pickle (e.g., caching).
Overriden to remove metadata from the dict, since it shouldn't be pickled
and may in some instances be unpickleable.
"""
# return an instance of the first dict in MRO that isn't a DictWithMetadata
for base in self.__class__.__mro__:
if not isinstance(base, DictWithMetadata) and isinstance(base, dict):
return base(self)
class SortedDictWithMetadata(SortedDict, DictWithMetadata):
"""
A sorted dict-like object, that can have additional properties attached.
"""
pass
def _is_protected_type(obj):
"""
True if the object is a native datatype that does not need to
be serialized further.
"""
return isinstance(obj, (
types.NoneType,
int, long,
datetime.datetime, datetime.date, datetime.time,
float, Decimal,
basestring)
)
def _get_declared_fields(bases, attrs):
"""
Create a list of serializer field instances from the passed in 'attrs',
plus any fields on the base classes (in 'bases').
Note that all fields from the base classes are used.
"""
fields = [(field_name, attrs.pop(field_name))
for field_name, obj in attrs.items()
if isinstance(obj, Field)]
fields.sort(key=lambda x: x[1].creation_counter)
# If this class is subclassing another Serializer, add that Serializer's
# fields. Note that we loop over the bases in *reverse*. This is necessary
# in order to maintain the correct order of fields.
for base in bases[::-1]:
if hasattr(base, 'base_fields'):
fields = base.base_fields.items() + fields
return SortedDict(fields)
class SerializerMetaclass(type):
def __new__(cls, name, bases, attrs):
attrs['base_fields'] = _get_declared_fields(bases, attrs)
return super(SerializerMetaclass, cls).__new__(cls, name, bases, attrs)
class SerializerOptions(object):
"""
Meta class options for Serializer
"""
def __init__(self, meta):
self.depth = getattr(meta, 'depth', 0)
self.fields = getattr(meta, 'fields', ())
self.exclude = getattr(meta, 'exclude', ())
class BaseSerializer(Field):
class Meta(object):
pass
_options_class = SerializerOptions
_dict_class = SortedDictWithMetadata # Set to unsorted dict for backwards compatibility with unsorted implementations.
def __init__(self, instance=None, data=None, files=None,
context=None, partial=False, **kwargs):
super(BaseSerializer, self).__init__(**kwargs)
self.opts = self._options_class(self.Meta)
self.parent = None
self.root = None
self.partial = partial
self.context = context or {}
self.init_data = data
self.init_files = files
self.object = instance
self.fields = self.get_fields()
self._data = None
self._files = None
self._errors = None
#####
# Methods to determine which fields to use when (de)serializing objects.
def get_default_fields(self):
"""
Return the complete set of default fields for the object, as a dict.
"""
return {}
def get_fields(self):
"""
Returns the complete set of fields for the object as a dict.
This will be the set of any explicitly declared fields,
plus the set of fields returned by get_default_fields().
"""
ret = SortedDict()
# Get the explicitly declared fields
base_fields = copy.deepcopy(self.base_fields)
for key, field in base_fields.items():
ret[key] = field
# Add in the default fields
default_fields = self.get_default_fields()
for key, val in default_fields.items():
if key not in ret:
ret[key] = val
# If 'fields' is specified, use those fields, in that order.
if self.opts.fields:
new = SortedDict()
for key in self.opts.fields:
new[key] = ret[key]
ret = new
# Remove anything in 'exclude'
if self.opts.exclude:
for key in self.opts.exclude:
ret.pop(key, None)
for key, field in ret.items():
field.initialize(parent=self, field_name=key)
return ret
#####
# Field methods - used when the serializer class is itself used as a field.
def initialize(self, parent, field_name):
"""
Same behaviour as usual Field, except that we need to keep track
of state so that we can deal with handling maximum depth.
"""
super(BaseSerializer, self).initialize(parent, field_name)
if parent.opts.depth:
self.opts.depth = parent.opts.depth - 1
#####
# Methods to convert or revert from objects <--> primitive representations.
def get_field_key(self, field_name):
"""
Return the key that should be used for a given field.
"""
return field_name
def convert_object(self, obj):
"""
Core of serialization.
Convert an object into a dictionary of serialized field values.
"""
ret = self._dict_class()
ret.fields = {}
for field_name, field in self.fields.items():
field.initialize(parent=self, field_name=field_name)
key = self.get_field_key(field_name)
value = field.field_to_native(obj, field_name)
ret[key] = value
ret.fields[key] = field
return ret
def restore_fields(self, data, files):
"""
Core of deserialization, together with `restore_object`.
Converts a dictionary of data into a dictionary of deserialized fields.
"""
reverted_data = {}
if data is not None and not isinstance(data, dict):
self._errors['non_field_errors'] = [u'Invalid data']
return None
for field_name, field in self.fields.items():
field.initialize(parent=self, field_name=field_name)
try:
field.field_from_native(data, files, field_name, reverted_data)
except ValidationError as err:
self._errors[field_name] = list(err.messages)
return reverted_data
def perform_validation(self, attrs):
"""
Run `validate_<fieldname>()` and `validate()` methods on the serializer
"""
for field_name, field in self.fields.items():
if field_name in self._errors:
continue
try:
validate_method = getattr(self, 'validate_%s' % field_name, None)
if validate_method:
source = field.source or field_name
attrs = validate_method(attrs, source)
except ValidationError as err:
self._errors[field_name] = self._errors.get(field_name, []) + list(err.messages)
# If there are already errors, we don't run .validate() because
# field-validation failed and thus `attrs` may not be complete.
# which in turn can cause inconsistent validation errors.
if not self._errors:
try:
attrs = self.validate(attrs)
except ValidationError as err:
if hasattr(err, 'message_dict'):
for field_name, error_messages in err.message_dict.items():
self._errors[field_name] = self._errors.get(field_name, []) + list(error_messages)
elif hasattr(err, 'messages'):
self._errors['non_field_errors'] = err.messages
return attrs
def validate(self, attrs):
"""
Stub method, to be overridden in Serializer subclasses
"""
return attrs
def restore_object(self, attrs, instance=None):
"""
Deserialize a dictionary of attributes into an object instance.
You should override this method to control how deserialized objects
are instantiated.
"""
if instance is not None:
instance.update(attrs)
return instance
return attrs
def to_native(self, obj):
"""
Serialize objects -> primitives.
"""
# Note: At the moment we have an ugly hack to determine if we should
# walk over iterables. At some point, serializers will require an
# explicit `many=True` in order to iterate over a set, and this hack
# will disappear.
if hasattr(obj, '__iter__') and not isinstance(obj, Page):
return [self.convert_object(item) for item in obj]
return self.convert_object(obj)
def from_native(self, data, files):
"""
Deserialize primitives -> objects.
"""
if hasattr(data, '__iter__') and not isinstance(data, dict):
# TODO: error data when deserializing lists
return [self.from_native(item, None) for item in data]
self._errors = {}
if data is not None or files is not None:
attrs = self.restore_fields(data, files)
attrs = self.perform_validation(attrs)
else:
self._errors['non_field_errors'] = ['No input provided']
if not self._errors:
return self.restore_object(attrs, instance=getattr(self, 'object', None))
def field_to_native(self, obj, field_name):
"""
Override default so that we can apply ModelSerializer as a nested
field to relationships.
"""
if self.source == '*':
return self.to_native(obj)
try:
if self.source:
for component in self.source.split('.'):
obj = getattr(obj, component)
if is_simple_callable(obj):
obj = obj()
else:
obj = getattr(obj, field_name)
if is_simple_callable(obj):
obj = obj()
except ObjectDoesNotExist:
return None
# If the object has an "all" method, assume it's a relationship
if is_simple_callable(getattr(obj, 'all', None)):
return [self.to_native(item) for item in obj.all()]
if obj is None:
return None
return self.to_native(obj)
@property
def errors(self):
"""
Run deserialization and return error data,
setting self.object if no errors occurred.
"""
if self._errors is None:
obj = self.from_native(self.init_data, self.init_files)
if not self._errors:
self.object = obj
return self._errors
def is_valid(self):
return not self.errors
@property
def data(self):
if self._data is None:
self._data = self.to_native(self.object)
return self._data
def save(self):
"""
Save the deserialized object and return it.
"""
self.object.save()
return self.object
class Serializer(BaseSerializer):
__metaclass__ = SerializerMetaclass
class ModelSerializerOptions(SerializerOptions):
"""
Meta class options for ModelSerializer
"""
def __init__(self, meta):
super(ModelSerializerOptions, self).__init__(meta)
self.model = getattr(meta, 'model', None)
self.read_only_fields = getattr(meta, 'read_only_fields', ())
class ModelSerializer(Serializer):
"""
A serializer that deals with model instances and querysets.
"""
_options_class = ModelSerializerOptions
def get_default_fields(self):
"""
Return all the fields that should be serialized for the model.
"""
cls = self.opts.model
opts = get_concrete_model(cls)._meta
pk_field = opts.pk
while pk_field.rel:
pk_field = pk_field.rel.to._meta.pk
fields = [pk_field]
fields += [field for field in opts.fields if field.serialize]
fields += [field for field in opts.many_to_many if field.serialize]
ret = SortedDict()
nested = bool(self.opts.depth)
is_pk = True # First field in the list is the pk
for model_field in fields:
if is_pk:
field = self.get_pk_field(model_field)
is_pk = False
elif model_field.rel and nested:
field = self.get_nested_field(model_field)
elif model_field.rel:
to_many = isinstance(model_field,
models.fields.related.ManyToManyField)
field = self.get_related_field(model_field, to_many=to_many)
else:
field = self.get_field(model_field)
if field:
ret[model_field.name] = field
for field_name in self.opts.read_only_fields:
assert field_name in ret, \
"read_only_fields on '%s' included invalid item '%s'" % \
(self.__class__.__name__, field_name)
ret[field_name].read_only = True
return ret
def get_pk_field(self, model_field):
"""
Returns a default instance of the pk field.
"""
return self.get_field(model_field)
def get_nested_field(self, model_field):
"""
Creates a default instance of a nested relational field.
"""
class NestedModelSerializer(ModelSerializer):
class Meta:
model = model_field.rel.to
return NestedModelSerializer()
def get_related_field(self, model_field, to_many=False):
"""
Creates a default instance of a flat relational field.
"""
# TODO: filter queryset using:
# .using(db).complex_filter(self.rel.limit_choices_to)
kwargs = {
'null': model_field.null or model_field.blank,
'queryset': model_field.rel.to._default_manager
}
if to_many:
return ManyPrimaryKeyRelatedField(**kwargs)
return PrimaryKeyRelatedField(**kwargs)
def get_field(self, model_field):
"""
Creates a default instance of a basic non-relational field.
"""
kwargs = {}
kwargs['blank'] = model_field.blank
if model_field.null or model_field.blank:
kwargs['required'] = False
if isinstance(model_field, models.AutoField) or not model_field.editable:
kwargs['read_only'] = True
if model_field.has_default():
kwargs['required'] = False
kwargs['default'] = model_field.get_default()
if issubclass(model_field.__class__, models.TextField):
kwargs['widget'] = widgets.Textarea
# TODO: TypedChoiceField?
if model_field.flatchoices: # This ModelField contains choices
kwargs['choices'] = model_field.flatchoices
return ChoiceField(**kwargs)
field_mapping = {
models.AutoField: IntegerField,
models.FloatField: FloatField,
models.IntegerField: IntegerField,
models.PositiveIntegerField: IntegerField,
models.SmallIntegerField: IntegerField,
models.PositiveSmallIntegerField: IntegerField,
models.DateTimeField: DateTimeField,
models.DateField: DateField,
models.EmailField: EmailField,
models.CharField: CharField,
models.URLField: URLField,
models.SlugField: SlugField,
models.TextField: CharField,
models.CommaSeparatedIntegerField: CharField,
models.BooleanField: BooleanField,
models.FileField: FileField,
models.ImageField: ImageField,
}
try:
return field_mapping[model_field.__class__](**kwargs)
except KeyError:
return ModelField(model_field=model_field, **kwargs)
def get_validation_exclusions(self):
"""
Return a list of field names to exclude from model validation.
"""
cls = self.opts.model
opts = get_concrete_model(cls)._meta
exclusions = [field.name for field in opts.fields + opts.many_to_many]
for field_name, field in self.fields.items():
if field_name in exclusions and not field.read_only:
exclusions.remove(field_name)
return exclusions
def full_clean(self, instance):
"""
Perform Django's full_clean, and populate the `errors` dictionary
if any validation errors occur.
Note that we don't perform this inside the `.restore_object()` method,
so that subclasses can override `.restore_object()`, and still get
the full_clean validation checking.
"""
try:
instance.full_clean(exclude=self.get_validation_exclusions())
except ValidationError, err:
self._errors = err.message_dict
return None
return instance
def restore_object(self, attrs, instance=None):
"""
Restore the model instance.
"""
self.m2m_data = {}
self.related_data = {}
# Reverse fk relations
for (obj, model) in self.opts.model._meta.get_all_related_objects_with_model():
field_name = obj.field.related_query_name()
if field_name in attrs:
self.related_data[field_name] = attrs.pop(field_name)
# Reverse m2m relations
for (obj, model) in self.opts.model._meta.get_all_related_m2m_objects_with_model():
field_name = obj.field.related_query_name()
if field_name in attrs:
self.m2m_data[field_name] = attrs.pop(field_name)
# Forward m2m relations
for field in self.opts.model._meta.many_to_many:
if field.name in attrs:
self.m2m_data[field.name] = attrs.pop(field.name)
if instance is not None:
for key, val in attrs.items():
setattr(instance, key, val)
else:
instance = self.opts.model(**attrs)
return instance
def from_native(self, data, files):
"""
Override the default method to also include model field validation.
"""
instance = super(ModelSerializer, self).from_native(data, files)
if instance:
return self.full_clean(instance)
def save(self):
"""
Save the deserialized object and return it.
"""
self.object.save()
if getattr(self, 'm2m_data', None):
for accessor_name, object_list in self.m2m_data.items():
setattr(self.object, accessor_name, object_list)
self.m2m_data = {}
if getattr(self, 'related_data', None):
for accessor_name, object_list in self.related_data.items():
setattr(self.object, accessor_name, object_list)
self.related_data = {}
return self.object
class HyperlinkedModelSerializerOptions(ModelSerializerOptions):
"""
Options for HyperlinkedModelSerializer
"""
def __init__(self, meta):
super(HyperlinkedModelSerializerOptions, self).__init__(meta)
self.view_name = getattr(meta, 'view_name', None)
class HyperlinkedModelSerializer(ModelSerializer):
"""
"""
_options_class = HyperlinkedModelSerializerOptions
_default_view_name = '%(model_name)s-detail'
url = HyperlinkedIdentityField()
def __init__(self, *args, **kwargs):
super(HyperlinkedModelSerializer, self).__init__(*args, **kwargs)
if self.opts.view_name is None:
self.opts.view_name = self._get_default_view_name(self.opts.model)
def _get_default_view_name(self, model):
"""
Return the view name to use if 'view_name' is not specified in 'Meta'
"""
model_meta = model._meta
format_kwargs = {
'app_label': model_meta.app_label,
'model_name': model_meta.object_name.lower()
}
return self._default_view_name % format_kwargs
def get_pk_field(self, model_field):
return None
def get_related_field(self, model_field, to_many):
"""
Creates a default instance of a flat relational field.
"""
# TODO: filter queryset using:
# .using(db).complex_filter(self.rel.limit_choices_to)
rel = model_field.rel.to
kwargs = {
'null': model_field.null,
'queryset': rel._default_manager,
'view_name': self._get_default_view_name(rel)
}
if to_many:
return ManyHyperlinkedRelatedField(**kwargs)
return HyperlinkedRelatedField(**kwargs)