django-rest-framework/rest_framework/relations.py
2013-08-31 17:20:49 +03:00

641 lines
24 KiB
Python

"""
Serializer fields that deal with relationships.
These fields allow you to specify the style that should be used to represent
model relationships, including hyperlinks, primary keys, or slugs.
"""
from __future__ import unicode_literals
from django.core.exceptions import ObjectDoesNotExist, ValidationError
from django.core.urlresolvers import resolve, get_script_prefix, NoReverseMatch
from django import forms
from django.db.models.fields import BLANK_CHOICE_DASH
from django.forms import widgets
from django.forms.models import ModelChoiceIterator
from django.utils.translation import ugettext_lazy as _
from rest_framework.fields import Field, WritableField, get_component, is_simple_callable
from rest_framework.reverse import reverse
from rest_framework.compat import urlparse
from rest_framework.compat import smart_text
import warnings
##### Relational fields #####
# Not actually Writable, but subclasses may need to be.
class RelatedField(WritableField):
"""
Base class for related model fields.
This represents a relationship using the unicode representation of the target.
"""
widget = widgets.Select
many_widget = widgets.SelectMultiple
form_field_class = forms.ChoiceField
many_form_field_class = forms.MultipleChoiceField
cache_choices = False
empty_label = None
read_only = True
many = False
def __init__(self, *args, **kwargs):
# 'null' is to be deprecated in favor of 'required'
if 'null' in kwargs:
warnings.warn('The `null` keyword argument is deprecated. '
'Use the `required` keyword argument instead.',
DeprecationWarning, stacklevel=2)
kwargs['required'] = not kwargs.pop('null')
queryset = kwargs.pop('queryset', None)
self.many = kwargs.pop('many', self.many)
if self.many:
self.widget = self.many_widget
self.form_field_class = self.many_form_field_class
kwargs['read_only'] = kwargs.pop('read_only', self.read_only)
super(RelatedField, self).__init__(*args, **kwargs)
if not self.required:
self.empty_label = BLANK_CHOICE_DASH[0][1]
self.queryset = queryset
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 Exception:
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 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_text(obj)
ident = smart_text(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):
try:
if self.source == '*':
return self.to_native(obj)
source = self.source or field_name
value = obj
for component in source.split('.'):
if value is None:
break
value = get_component(value, component)
except ObjectDoesNotExist:
return None
if value is None:
return None
if self.many:
if is_simple_callable(getattr(value, 'all', None)):
return [self.to_native(item) for item in value.all()]
else:
# Also support non-queryset iterables.
# This allows us to also support plain lists of related items.
return [self.to_native(item) for item in value]
return self.to_native(value)
def field_from_native(self, data, files, field_name, into):
if self.read_only:
return
try:
if self.many:
try:
# Form data
value = data.getlist(field_name)
if value == [''] or value == []:
raise KeyError
except AttributeError:
# Non-form data
value = data[field_name]
else:
value = data[field_name]
except KeyError:
if self.partial:
return
value = [] if self.many else None
if value in (None, '') and self.required:
raise ValidationError(self.error_messages['required'])
elif value in (None, ''):
into[(self.source or field_name)] = None
elif self.many:
into[(self.source or field_name)] = [self.from_native(item) for item in value]
else:
into[(self.source or field_name)] = self.from_native(value)
### PrimaryKey relationships
class PrimaryKeyRelatedField(RelatedField):
"""
Represents a relationship as a pk value.
"""
read_only = False
default_error_messages = {
'does_not_exist': _("Invalid pk '%s' - object does not exist."),
'incorrect_type': _('Incorrect type. Expected pk value, received %s.'),
}
# 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_text(obj)
ident = smart_text(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_text(data)
raise ValidationError(msg)
except (TypeError, ValueError):
received = type(data).__name__
msg = self.error_messages['incorrect_type'] % received
raise ValidationError(msg)
def field_to_native(self, obj, field_name):
if self.many:
# To-many relationship
queryset = None
if not self.source:
# Prefer obj.serializable_value for performance reasons
try:
queryset = obj.serializable_value(field_name)
except AttributeError:
pass
if queryset is None:
# RelatedManager (reverse relationship)
source = self.source or field_name
queryset = obj
for component in source.split('.'):
if queryset is None:
return []
queryset = get_component(queryset, component)
# Forward relationship
if is_simple_callable(getattr(queryset, 'all', None)):
return [self.to_native(item.pk) for item in queryset.all()]
else:
# Also support non-queryset iterables.
# This allows us to also support plain lists of related items.
return [self.to_native(item.pk) for item in queryset]
# To-one relationship
try:
# Prefer obj.serializable_value for performance reasons
pk = obj.serializable_value(self.source or field_name)
except AttributeError:
# RelatedObject (reverse relationship)
try:
pk = getattr(obj, self.source or field_name).pk
except (ObjectDoesNotExist, AttributeError):
return None
# Forward relationship
return self.to_native(pk)
### Slug relationships
class SlugRelatedField(RelatedField):
"""
Represents a relationship using a unique field on the target.
"""
read_only = False
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, smart_text(data)))
except (TypeError, ValueError):
msg = self.error_messages['invalid']
raise ValidationError(msg)
### Hyperlinked relationships
class HyperlinkedRelatedField(RelatedField):
"""
Represents a relationship using hyperlinking.
"""
read_only = False
lookup_field = 'pk'
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."),
'incorrect_type': _('Incorrect type. Expected url string, received %s.'),
}
# These are all pending deprecation
pk_url_kwarg = 'pk'
slug_field = 'slug'
slug_url_kwarg = None # Defaults to same as `slug_field` unless overridden
def __init__(self, *args, **kwargs):
try:
self.view_name = kwargs.pop('view_name')
except KeyError:
raise ValueError("Hyperlinked field requires 'view_name' kwarg")
self.lookup_field = kwargs.pop('lookup_field', self.lookup_field)
self.format = kwargs.pop('format', None)
# These are pending deprecation
if 'pk_url_kwarg' in kwargs:
msg = 'pk_url_kwarg is pending deprecation. Use lookup_field instead.'
warnings.warn(msg, PendingDeprecationWarning, stacklevel=2)
if 'slug_url_kwarg' in kwargs:
msg = 'slug_url_kwarg is pending deprecation. Use lookup_field instead.'
warnings.warn(msg, PendingDeprecationWarning, stacklevel=2)
if 'slug_field' in kwargs:
msg = 'slug_field is pending deprecation. Use lookup_field instead.'
warnings.warn(msg, PendingDeprecationWarning, stacklevel=2)
self.pk_url_kwarg = kwargs.pop('pk_url_kwarg', self.pk_url_kwarg)
self.slug_field = kwargs.pop('slug_field', self.slug_field)
default_slug_kwarg = self.slug_url_kwarg or self.slug_field
self.slug_url_kwarg = kwargs.pop('slug_url_kwarg', default_slug_kwarg)
super(HyperlinkedRelatedField, self).__init__(*args, **kwargs)
def get_url(self, obj, view_name, request, format):
"""
Given an object, return the URL that hyperlinks to the object.
May raise a `NoReverseMatch` if the `view_name` and `lookup_field`
attributes are not configured to correctly match the URL conf.
"""
lookup_field = getattr(obj, self.lookup_field)
kwargs = {self.lookup_field: lookup_field}
try:
return reverse(view_name, kwargs=kwargs, request=request, format=format)
except NoReverseMatch:
pass
if self.pk_url_kwarg != 'pk':
# Only try pk if it has been explicitly set.
# Otherwise, the default `lookup_field = 'pk'` has us covered.
pk = obj.pk
kwargs = {self.pk_url_kwarg: pk}
try:
return reverse(view_name, kwargs=kwargs, request=request, format=format)
except NoReverseMatch:
pass
slug = getattr(obj, self.slug_field, None)
if slug is not None:
# Only try slug if it corresponds to an attribute on the object.
kwargs = {self.slug_url_kwarg: slug}
try:
ret = reverse(view_name, kwargs=kwargs, request=request, format=format)
if self.slug_field == 'slug' and self.slug_url_kwarg == 'slug':
# If the lookup succeeds using the default slug params,
# then `slug_field` is being used implicitly, and we
# we need to warn about the pending deprecation.
msg = 'Implicit slug field hyperlinked fields are pending deprecation.' \
'You should set `lookup_field=slug` on the HyperlinkedRelatedField.'
warnings.warn(msg, PendingDeprecationWarning, stacklevel=2)
return ret
except NoReverseMatch:
pass
raise NoReverseMatch()
def get_object(self, queryset, view_name, view_args, view_kwargs):
"""
Return the object corresponding to a matched URL.
Takes the matched URL conf arguments, and the queryset, and should
return an object instance, or raise an `ObjectDoesNotExist` exception.
"""
lookup = view_kwargs.get(self.lookup_field, None)
pk = view_kwargs.get(self.pk_url_kwarg, None)
slug = view_kwargs.get(self.slug_url_kwarg, None)
if lookup is not None:
filter_kwargs = {self.lookup_field: lookup}
elif pk is not None:
filter_kwargs = {'pk': pk}
elif slug is not None:
filter_kwargs = {self.slug_field: slug}
else:
raise ObjectDoesNotExist()
return queryset.get(**filter_kwargs)
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)
if request is None:
msg = (
"Using `HyperlinkedRelatedField` without including the request "
"in the serializer context is deprecated. "
"Add `context={'request': request}` when instantiating "
"the serializer."
)
warnings.warn(msg, DeprecationWarning, stacklevel=4)
# If the object has not yet been saved then we cannot hyperlink to it.
if getattr(obj, 'pk', None) is None:
return
# Return the hyperlink, or error if incorrectly configured.
try:
return self.get_url(obj, view_name, request, format)
except NoReverseMatch:
msg = (
'Could not resolve URL for hyperlinked relationship using '
'view name "%s". You may have failed to include the related '
'model in your API, or incorrectly configured the '
'`lookup_field` attribute on this field.'
)
raise Exception(msg % view_name)
def from_native(self, value):
# Convert URL -> model instance pk
# TODO: Use values_list
queryset = self.queryset
if queryset is None:
raise Exception('Writable related fields must include a `queryset` argument')
try:
http_prefix = value.startswith(('http:', 'https:'))
except AttributeError:
msg = self.error_messages['incorrect_type']
raise ValidationError(msg % type(value).__name__)
if http_prefix:
# If needed convert absolute URLs to relative path
value = urlparse.urlparse(value).path
prefix = get_script_prefix()
if value.startswith(prefix):
value = '/' + value[len(prefix):]
try:
match = resolve(value)
except Exception:
raise ValidationError(self.error_messages['no_match'])
if match.view_name != self.view_name:
raise ValidationError(self.error_messages['incorrect_match'])
try:
return self.get_object(queryset, match.view_name,
match.args, match.kwargs)
except (ObjectDoesNotExist, TypeError, ValueError):
raise ValidationError(self.error_messages['does_not_exist'])
class HyperlinkedIdentityField(Field):
"""
Represents the instance, or a property on the instance, using hyperlinking.
"""
lookup_field = 'pk'
read_only = True
# These are all pending deprecation
pk_url_kwarg = 'pk'
slug_field = 'slug'
slug_url_kwarg = None # Defaults to same as `slug_field` unless overridden
def __init__(self, *args, **kwargs):
try:
self.view_name = kwargs.pop('view_name')
except KeyError:
msg = "HyperlinkedIdentityField requires 'view_name' argument"
raise ValueError(msg)
self.format = kwargs.pop('format', None)
lookup_field = kwargs.pop('lookup_field', None)
self.lookup_field = lookup_field or self.lookup_field
# These are pending deprecation
if 'pk_url_kwarg' in kwargs:
msg = 'pk_url_kwarg is pending deprecation. Use lookup_field instead.'
warnings.warn(msg, PendingDeprecationWarning, stacklevel=2)
if 'slug_url_kwarg' in kwargs:
msg = 'slug_url_kwarg is pending deprecation. Use lookup_field instead.'
warnings.warn(msg, PendingDeprecationWarning, stacklevel=2)
if 'slug_field' in kwargs:
msg = 'slug_field is pending deprecation. Use lookup_field instead.'
warnings.warn(msg, PendingDeprecationWarning, stacklevel=2)
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
if request is None:
warnings.warn("Using `HyperlinkedIdentityField` without including the "
"request in the serializer context is deprecated. "
"Add `context={'request': request}` when instantiating the serializer.",
DeprecationWarning, stacklevel=4)
# 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
# Return the hyperlink, or error if incorrectly configured.
try:
return self.get_url(obj, view_name, request, format)
except NoReverseMatch:
msg = (
'Could not resolve URL for hyperlinked relationship using '
'view name "%s". You may have failed to include the related '
'model in your API, or incorrectly configured the '
'`lookup_field` attribute on this field.'
)
raise Exception(msg % view_name)
def get_url(self, obj, view_name, request, format):
"""
Given an object, return the URL that hyperlinks to the object.
May raise a `NoReverseMatch` if the `view_name` and `lookup_field`
attributes are not configured to correctly match the URL conf.
"""
lookup_field = getattr(obj, self.lookup_field, None)
kwargs = {self.lookup_field: lookup_field}
# Handle unsaved object case
if lookup_field is None:
return None
try:
return reverse(view_name, kwargs=kwargs, request=request, format=format)
except NoReverseMatch:
pass
if self.pk_url_kwarg != 'pk':
# Only try pk lookup if it has been explicitly set.
# Otherwise, the default `lookup_field = 'pk'` has us covered.
kwargs = {self.pk_url_kwarg: obj.pk}
try:
return reverse(view_name, kwargs=kwargs, request=request, format=format)
except NoReverseMatch:
pass
slug = getattr(obj, self.slug_field, None)
if slug:
# Only use slug lookup if a slug field exists on the model
kwargs = {self.slug_url_kwarg: slug}
try:
return reverse(view_name, kwargs=kwargs, request=request, format=format)
except NoReverseMatch:
pass
raise NoReverseMatch()
### Old-style many classes for backwards compat
class ManyRelatedField(RelatedField):
def __init__(self, *args, **kwargs):
warnings.warn('`ManyRelatedField()` is deprecated. '
'Use `RelatedField(many=True)` instead.',
DeprecationWarning, stacklevel=2)
kwargs['many'] = True
super(ManyRelatedField, self).__init__(*args, **kwargs)
class ManyPrimaryKeyRelatedField(PrimaryKeyRelatedField):
def __init__(self, *args, **kwargs):
warnings.warn('`ManyPrimaryKeyRelatedField()` is deprecated. '
'Use `PrimaryKeyRelatedField(many=True)` instead.',
DeprecationWarning, stacklevel=2)
kwargs['many'] = True
super(ManyPrimaryKeyRelatedField, self).__init__(*args, **kwargs)
class ManySlugRelatedField(SlugRelatedField):
def __init__(self, *args, **kwargs):
warnings.warn('`ManySlugRelatedField()` is deprecated. '
'Use `SlugRelatedField(many=True)` instead.',
DeprecationWarning, stacklevel=2)
kwargs['many'] = True
super(ManySlugRelatedField, self).__init__(*args, **kwargs)
class ManyHyperlinkedRelatedField(HyperlinkedRelatedField):
def __init__(self, *args, **kwargs):
warnings.warn('`ManyHyperlinkedRelatedField()` is deprecated. '
'Use `HyperlinkedRelatedField(many=True)` instead.',
DeprecationWarning, stacklevel=2)
kwargs['many'] = True
super(ManyHyperlinkedRelatedField, self).__init__(*args, **kwargs)