django-rest-framework/rest_framework/relations.py
2013-01-07 14:34:45 +00:00

504 lines
17 KiB
Python

from django.core.exceptions import ObjectDoesNotExist, ValidationError
from django.core.urlresolvers import resolve, get_script_prefix
from django import forms
from django.forms import widgets
from django.forms.models import ModelChoiceIterator
from django.utils.encoding import smart_unicode
from django.utils.translation import ugettext_lazy as _
from rest_framework.fields import Field, WritableField
from rest_framework.reverse import reverse
from urlparse import urlparse
##### Relational fields #####
# Not actually Writable, but subclasses may need to be.
class RelatedField(WritableField):
"""
Base class for related model fields.
If not overridden, this represents a to-one relationship, using the unicode
representation of the target.
"""
widget = widgets.Select
cache_choices = False
empty_label = None
default_read_only = True # TODO: Remove this
def __init__(self, *args, **kwargs):
self.queryset = kwargs.pop('queryset', None)
self.null = kwargs.pop('null', False)
super(RelatedField, self).__init__(*args, **kwargs)
self.read_only = kwargs.pop('read_only', self.default_read_only)
def initialize(self, parent, field_name):
super(RelatedField, self).initialize(parent, field_name)
if self.queryset is None and not self.read_only:
try:
manager = getattr(self.parent.opts.model, self.source or field_name)
if hasattr(manager, 'related'): # Forward
self.queryset = manager.related.model._default_manager.all()
else: # Reverse
self.queryset = manager.field.rel.to._default_manager.all()
except:
raise
msg = ('Serializer related fields must include a `queryset`' +
' argument or set `read_only=True')
raise Exception(msg)
### We need this stuff to make form choices work...
# def __deepcopy__(self, memo):
# result = super(RelatedField, self).__deepcopy__(memo)
# result.queryset = result.queryset
# return result
def prepare_value(self, obj):
return self.to_native(obj)
def label_from_instance(self, obj):
"""
Return a readable representation for use with eg. select widgets.
"""
desc = smart_unicode(obj)
ident = smart_unicode(self.to_native(obj))
if desc == ident:
return desc
return "%s - %s" % (desc, ident)
def _get_queryset(self):
return self._queryset
def _set_queryset(self, queryset):
self._queryset = queryset
self.widget.choices = self.choices
queryset = property(_get_queryset, _set_queryset)
def _get_choices(self):
# If self._choices is set, then somebody must have manually set
# the property self.choices. In this case, just return self._choices.
if hasattr(self, '_choices'):
return self._choices
# Otherwise, execute the QuerySet in self.queryset to determine the
# choices dynamically. Return a fresh ModelChoiceIterator that has not been
# consumed. Note that we're instantiating a new ModelChoiceIterator *each*
# time _get_choices() is called (and, thus, each time self.choices is
# accessed) so that we can ensure the QuerySet has not been consumed. This
# construct might look complicated but it allows for lazy evaluation of
# the queryset.
return ModelChoiceIterator(self)
def _set_choices(self, value):
# Setting choices also sets the choices on the widget.
# choices can be any iterable, but we call list() on it because
# it will be consumed more than once.
self._choices = self.widget.choices = list(value)
choices = property(_get_choices, _set_choices)
### Regular serializer stuff...
def field_to_native(self, obj, field_name):
value = getattr(obj, self.source or field_name)
return self.to_native(value)
def field_from_native(self, data, files, field_name, into):
if self.read_only:
return
try:
value = data[field_name]
except KeyError:
if self.required:
raise ValidationError(self.error_messages['required'])
return
if value in (None, '') and not self.null:
raise ValidationError('Value may not be null')
elif value in (None, '') and self.null:
into[(self.source or field_name)] = None
else:
into[(self.source or field_name)] = self.from_native(value)
class ManyRelatedMixin(object):
"""
Mixin to convert a related field to a many related field.
"""
widget = widgets.SelectMultiple
def field_to_native(self, obj, field_name):
value = getattr(obj, self.source or field_name)
return [self.to_native(item) for item in value.all()]
def field_from_native(self, data, files, field_name, into):
if self.read_only:
return
try:
# Form data
value = data.getlist(self.source or field_name)
except:
# Non-form data
value = data.get(self.source or field_name)
else:
if value == ['']:
value = []
into[field_name] = [self.from_native(item) for item in value]
class ManyRelatedField(ManyRelatedMixin, RelatedField):
"""
Base class for related model managers.
If not overridden, this represents a to-many relationship, using the unicode
representations of the target, and is read-only.
"""
pass
### PrimaryKey relationships
class PrimaryKeyRelatedField(RelatedField):
"""
Represents a to-one relationship as a pk value.
"""
default_read_only = False
form_field_class = forms.ChoiceField
default_error_messages = {
'does_not_exist': _("Invalid pk '%s' - object does not exist."),
'invalid': _('Invalid value.'),
}
# TODO: Remove these field hacks...
def prepare_value(self, obj):
return self.to_native(obj.pk)
def label_from_instance(self, obj):
"""
Return a readable representation for use with eg. select widgets.
"""
desc = smart_unicode(obj)
ident = smart_unicode(self.to_native(obj.pk))
if desc == ident:
return desc
return "%s - %s" % (desc, ident)
# TODO: Possibly change this to just take `obj`, through prob less performant
def to_native(self, pk):
return pk
def from_native(self, data):
if self.queryset is None:
raise Exception('Writable related fields must include a `queryset` argument')
try:
return self.queryset.get(pk=data)
except ObjectDoesNotExist:
msg = self.error_messages['does_not_exist'] % smart_unicode(data)
raise ValidationError(msg)
except (TypeError, ValueError):
msg = self.error_messages['invalid']
raise ValidationError(msg)
def field_to_native(self, obj, field_name):
try:
# Prefer obj.serializable_value for performance reasons
pk = obj.serializable_value(self.source or field_name)
except AttributeError:
# RelatedObject (reverse relationship)
obj = getattr(obj, self.source or field_name)
return self.to_native(obj.pk)
# Forward relationship
return self.to_native(pk)
class ManyPrimaryKeyRelatedField(ManyRelatedField):
"""
Represents a to-many relationship as a pk value.
"""
default_read_only = False
form_field_class = forms.MultipleChoiceField
default_error_messages = {
'does_not_exist': _("Invalid pk '%s' - object does not exist."),
'invalid': _('Invalid value.'),
}
def prepare_value(self, obj):
return self.to_native(obj.pk)
def label_from_instance(self, obj):
"""
Return a readable representation for use with eg. select widgets.
"""
desc = smart_unicode(obj)
ident = smart_unicode(self.to_native(obj.pk))
if desc == ident:
return desc
return "%s - %s" % (desc, ident)
def to_native(self, pk):
return pk
def field_to_native(self, obj, field_name):
try:
# Prefer obj.serializable_value for performance reasons
queryset = obj.serializable_value(self.source or field_name)
except AttributeError:
# RelatedManager (reverse relationship)
queryset = getattr(obj, self.source or field_name)
return [self.to_native(item.pk) for item in queryset.all()]
# Forward relationship
return [self.to_native(item.pk) for item in queryset.all()]
def from_native(self, data):
if self.queryset is None:
raise Exception('Writable related fields must include a `queryset` argument')
try:
return self.queryset.get(pk=data)
except ObjectDoesNotExist:
msg = self.error_messages['does_not_exist'] % smart_unicode(data)
raise ValidationError(msg)
except (TypeError, ValueError):
msg = self.error_messages['invalid']
raise ValidationError(msg)
### Slug relationships
class SlugRelatedField(RelatedField):
default_read_only = False
form_field_class = forms.ChoiceField
default_error_messages = {
'does_not_exist': _("Object with %s=%s does not exist."),
'invalid': _('Invalid value.'),
}
def __init__(self, *args, **kwargs):
self.slug_field = kwargs.pop('slug_field', None)
assert self.slug_field, 'slug_field is required'
super(SlugRelatedField, self).__init__(*args, **kwargs)
def to_native(self, obj):
return getattr(obj, self.slug_field)
def from_native(self, data):
if self.queryset is None:
raise Exception('Writable related fields must include a `queryset` argument')
try:
return self.queryset.get(**{self.slug_field: data})
except ObjectDoesNotExist:
raise ValidationError(self.error_messages['does_not_exist'] %
(self.slug_field, unicode(data)))
except (TypeError, ValueError):
msg = self.error_messages['invalid']
raise ValidationError(msg)
class ManySlugRelatedField(ManyRelatedMixin, SlugRelatedField):
form_field_class = forms.MultipleChoiceField
### Hyperlinked relationships
class HyperlinkedRelatedField(RelatedField):
"""
Represents a to-one relationship, using hyperlinking.
"""
pk_url_kwarg = 'pk'
slug_field = 'slug'
slug_url_kwarg = None # Defaults to same as `slug_field` unless overridden
default_read_only = False
form_field_class = forms.ChoiceField
default_error_messages = {
'no_match': _('Invalid hyperlink - No URL match'),
'incorrect_match': _('Invalid hyperlink - Incorrect URL match'),
'configuration_error': _('Invalid hyperlink due to configuration error'),
'does_not_exist': _("Invalid hyperlink - object does not exist."),
'invalid': _('Invalid value.'),
}
def __init__(self, *args, **kwargs):
try:
self.view_name = kwargs.pop('view_name')
except:
raise ValueError("Hyperlinked field requires 'view_name' kwarg")
self.slug_field = kwargs.pop('slug_field', self.slug_field)
default_slug_kwarg = self.slug_url_kwarg or self.slug_field
self.pk_url_kwarg = kwargs.pop('pk_url_kwarg', self.pk_url_kwarg)
self.slug_url_kwarg = kwargs.pop('slug_url_kwarg', default_slug_kwarg)
self.format = kwargs.pop('format', None)
super(HyperlinkedRelatedField, self).__init__(*args, **kwargs)
def get_slug_field(self):
"""
Get the name of a slug field to be used to look up by slug.
"""
return self.slug_field
def to_native(self, obj):
view_name = self.view_name
request = self.context.get('request', None)
format = self.format or self.context.get('format', None)
pk = getattr(obj, 'pk', None)
if pk is None:
return
kwargs = {self.pk_url_kwarg: pk}
try:
return reverse(view_name, kwargs=kwargs, request=request, format=format)
except:
pass
slug = getattr(obj, self.slug_field, None)
if not slug:
raise Exception('Could not resolve URL for field using view name "%s"' % view_name)
kwargs = {self.slug_url_kwarg: slug}
try:
return reverse(self.view_name, kwargs=kwargs, request=request, format=format)
except:
pass
kwargs = {self.pk_url_kwarg: obj.pk, self.slug_url_kwarg: slug}
try:
return reverse(self.view_name, kwargs=kwargs, request=request, format=format)
except:
pass
raise Exception('Could not resolve URL for field using view name "%s"' % view_name)
def from_native(self, value):
# Convert URL -> model instance pk
# TODO: Use values_list
if self.queryset is None:
raise Exception('Writable related fields must include a `queryset` argument')
try:
http_prefix = value.startswith('http:') or value.startswith('https:')
except AttributeError:
msg = self.error_messages['invalid']
raise ValidationError(msg)
if http_prefix:
# If needed convert absolute URLs to relative path
value = urlparse(value).path
prefix = get_script_prefix()
if value.startswith(prefix):
value = '/' + value[len(prefix):]
try:
match = resolve(value)
except:
raise ValidationError(self.error_messages['no_match'])
if match.view_name != self.view_name:
raise ValidationError(self.error_messages['incorrect_match'])
pk = match.kwargs.get(self.pk_url_kwarg, None)
slug = match.kwargs.get(self.slug_url_kwarg, None)
# Try explicit primary key.
if pk is not None:
queryset = self.queryset.filter(pk=pk)
# Next, try looking up by slug.
elif slug is not None:
slug_field = self.get_slug_field()
queryset = self.queryset.filter(**{slug_field: slug})
# If none of those are defined, it's probably a configuation error.
else:
raise ValidationError(self.error_messages['configuration_error'])
try:
obj = queryset.get()
except ObjectDoesNotExist:
raise ValidationError(self.error_messages['does_not_exist'])
except (TypeError, ValueError):
msg = self.error_messages['invalid']
raise ValidationError(msg)
return obj
class ManyHyperlinkedRelatedField(ManyRelatedMixin, HyperlinkedRelatedField):
"""
Represents a to-many relationship, using hyperlinking.
"""
form_field_class = forms.MultipleChoiceField
class HyperlinkedIdentityField(Field):
"""
Represents the instance, or a property on the instance, using hyperlinking.
"""
pk_url_kwarg = 'pk'
slug_field = 'slug'
slug_url_kwarg = None # Defaults to same as `slug_field` unless overridden
def __init__(self, *args, **kwargs):
# TODO: Make view_name mandatory, and have the
# HyperlinkedModelSerializer set it on-the-fly
self.view_name = kwargs.pop('view_name', None)
# Optionally the format of the target hyperlink may be specified
self.format = kwargs.pop('format', None)
self.slug_field = kwargs.pop('slug_field', self.slug_field)
default_slug_kwarg = self.slug_url_kwarg or self.slug_field
self.pk_url_kwarg = kwargs.pop('pk_url_kwarg', self.pk_url_kwarg)
self.slug_url_kwarg = kwargs.pop('slug_url_kwarg', default_slug_kwarg)
super(HyperlinkedIdentityField, self).__init__(*args, **kwargs)
def field_to_native(self, obj, field_name):
request = self.context.get('request', None)
format = self.context.get('format', None)
view_name = self.view_name or self.parent.opts.view_name
kwargs = {self.pk_url_kwarg: obj.pk}
# By default use whatever format is given for the current context
# unless the target is a different type to the source.
#
# Eg. Consider a HyperlinkedIdentityField pointing from a json
# representation to an html property of that representation...
#
# '/snippets/1/' should link to '/snippets/1/highlight/'
# ...but...
# '/snippets/1/.json' should link to '/snippets/1/highlight/.html'
if format and self.format and self.format != format:
format = self.format
try:
return reverse(view_name, kwargs=kwargs, request=request, format=format)
except:
pass
slug = getattr(obj, self.slug_field, None)
if not slug:
raise Exception('Could not resolve URL for field using view name "%s"' % view_name)
kwargs = {self.slug_url_kwarg: slug}
try:
return reverse(self.view_name, kwargs=kwargs, request=request, format=format)
except:
pass
kwargs = {self.pk_url_kwarg: obj.pk, self.slug_url_kwarg: slug}
try:
return reverse(self.view_name, kwargs=kwargs, request=request, format=format)
except:
pass
raise Exception('Could not resolve URL for field using view name "%s"' % view_name)