"""
Renderers
"""
import copy
from collections import OrderedDict, defaultdict
from collections.abc import Iterable
import inflection
from django.db.models import Manager
from django.utils import encoding
from rest_framework import relations, renderers
from rest_framework.fields import SkipField, get_attribute
from rest_framework.relations import PKOnlyObject
from rest_framework.serializers import BaseSerializer, ListSerializer, Serializer
from rest_framework.settings import api_settings
import rest_framework_json_api
from rest_framework_json_api import utils
from rest_framework_json_api.relations import HyperlinkedMixin, ResourceRelatedField, SkipDataMixin
from rest_framework_json_api.settings import json_api_settings
class JSONRenderer(renderers.JSONRenderer):
"""
The `JSONRenderer` exposes a number of methods that you may override if you need highly
custom rendering control.
Render a JSON response per the JSON API spec:
.. code-block:: json
{
"data": [
{
"type": "companies",
"id": 1,
"attributes": {
"name": "Mozilla",
"slug": "mozilla",
"date-created": "2014-03-13 16:33:37"
}
}
]
}
"""
media_type = 'application/vnd.api+json'
format = 'vnd.api+json'
@classmethod
def extract_attributes(cls, fields, resource):
"""
Builds the `attributes` object of the JSON API resource object.
"""
data = OrderedDict()
render_nested_as_attribute = json_api_settings.SERIALIZE_NESTED_SERIALIZERS_AS_ATTRIBUTE
for field_name, field in iter(fields.items()):
# ID is always provided in the root of JSON API so remove it from attributes
if field_name == 'id':
continue
# don't output a key for write only fields
if fields[field_name].write_only:
continue
# Skip fields with relations
if isinstance(
field, (relations.RelatedField, relations.ManyRelatedField)
):
continue
if isinstance(field, BaseSerializer) and not render_nested_as_attribute:
continue
# Skip read_only attribute fields when `resource` is an empty
# serializer. Prevents the "Raw Data" form of the browsable API
# from rendering `"foo": null` for read only fields
try:
resource[field_name]
except KeyError:
if fields[field_name].read_only:
continue
data.update({
field_name: resource.get(field_name)
})
return utils.format_field_names(data)
@classmethod
def extract_relationships(cls, fields, resource, resource_instance):
"""
Builds the relationships top level object based on related serializers.
"""
# Avoid circular deps
from rest_framework_json_api.relations import ResourceRelatedField
data = OrderedDict()
render_nested_as_attribute = json_api_settings.SERIALIZE_NESTED_SERIALIZERS_AS_ATTRIBUTE
# Don't try to extract relationships from a non-existent resource
if resource_instance is None:
return
for field_name, field in iter(fields.items()):
# Skip URL field
if field_name == api_settings.URL_FIELD_NAME:
continue
# don't output a key for write only fields
if fields[field_name].write_only:
continue
# Skip fields without relations
if not isinstance(
field, (relations.RelatedField, relations.ManyRelatedField, BaseSerializer)
):
continue
if isinstance(field, BaseSerializer) and render_nested_as_attribute:
continue
source = field.source
relation_type = utils.get_related_resource_type(field)
if isinstance(field, relations.HyperlinkedIdentityField):
resolved, relation_instance = utils.get_relation_instance(
resource_instance, source, field.parent
)
if not resolved:
continue
# special case for HyperlinkedIdentityField
relation_data = list()
# Don't try to query an empty relation
relation_queryset = relation_instance \
if relation_instance is not None else list()
for related_object in relation_queryset:
relation_data.append(
OrderedDict([
('type', relation_type),
('id', encoding.force_str(related_object.pk))
])
)
data.update({field_name: {
'links': {
"related": resource.get(field_name)},
'data': relation_data,
'meta': {
'count': len(relation_data)
}
}})
continue
relation_data = {}
if isinstance(field, HyperlinkedMixin):
field_links = field.get_links(resource_instance, field.related_link_lookup_field)
relation_data.update({'links': field_links} if field_links else dict())
data.update({field_name: relation_data})
if isinstance(field, (ResourceRelatedField, )):
if not isinstance(field, SkipDataMixin):
relation_data.update({'data': resource.get(field_name)})
data.update({field_name: relation_data})
continue
if isinstance(
field, (relations.PrimaryKeyRelatedField, relations.HyperlinkedRelatedField)
):
resolved, relation = utils.get_relation_instance(
resource_instance, '%s_id' % source, field.parent
)
if not resolved:
continue
relation_id = relation if resource.get(field_name) else None
relation_data = {
'data': (
OrderedDict([
('type', relation_type), ('id', encoding.force_str(relation_id))
])
if relation_id is not None else None)
}
if (
isinstance(field, relations.HyperlinkedRelatedField) and
resource.get(field_name)
):
relation_data.update(
{
'links': {
'related': resource.get(field_name)
}
}
)
data.update({field_name: relation_data})
continue
if isinstance(field, relations.ManyRelatedField):
resolved, relation_instance = utils.get_relation_instance(
resource_instance, source, field.parent
)
if not resolved:
continue
relation_data = {}
if isinstance(resource.get(field_name), Iterable):
relation_data.update(
{
'meta': {'count': len(resource.get(field_name))}
}
)
if isinstance(field.child_relation, ResourceRelatedField):
# special case for ResourceRelatedField
relation_data.update(
{'data': resource.get(field_name)}
)
if isinstance(field.child_relation, HyperlinkedMixin):
field_links = field.child_relation.get_links(
resource_instance,
field.child_relation.related_link_lookup_field
)
relation_data.update(
{'links': field_links}
if field_links else dict()
)
data.update({field_name: relation_data})
continue
relation_data = list()
for nested_resource_instance in relation_instance:
nested_resource_instance_type = (
relation_type or
utils.get_resource_type_from_instance(nested_resource_instance)
)
relation_data.append(OrderedDict([
('type', nested_resource_instance_type),
('id', encoding.force_str(nested_resource_instance.pk))
]))
data.update({
field_name: {
'data': relation_data,
'meta': {
'count': len(relation_data)
}
}
})
continue
if isinstance(field, ListSerializer):
resolved, relation_instance = utils.get_relation_instance(
resource_instance, source, field.parent
)
if not resolved:
continue
relation_data = list()
serializer_data = resource.get(field_name)
resource_instance_queryset = list(relation_instance)
if isinstance(serializer_data, list):
for position in range(len(serializer_data)):
nested_resource_instance = resource_instance_queryset[position]
nested_resource_instance_type = (
relation_type or
utils.get_resource_type_from_instance(nested_resource_instance)
)
relation_data.append(OrderedDict([
('type', nested_resource_instance_type),
('id', encoding.force_str(nested_resource_instance.pk))
]))
data.update({field_name: {'data': relation_data}})
continue
if isinstance(field, Serializer):
relation_instance_id = getattr(resource_instance, source + "_id", None)
if not relation_instance_id:
resolved, relation_instance = utils.get_relation_instance(
resource_instance, source, field.parent
)
if not resolved:
continue
if relation_instance is not None:
relation_instance_id = relation_instance.pk
data.update({
field_name: {
'data': (
OrderedDict([
('type', relation_type),
('id', encoding.force_str(relation_instance_id))
]) if resource.get(field_name) else None)
}
})
continue
return utils.format_field_names(data)
@classmethod
def extract_relation_instance(cls, field, resource_instance):
"""
Determines what instance represents given relation and extracts it.
Relation instance is determined exactly same way as it determined
in parent serializer
"""
try:
res = field.get_attribute(resource_instance)
if isinstance(res, PKOnlyObject):
return get_attribute(resource_instance, field.source_attrs)
return res
except SkipField:
return None
@classmethod
def extract_included(cls, fields, resource, resource_instance, included_resources,
included_cache):
"""
Adds related data to the top level included key when the request includes
?include=example,example_field2
"""
# this function may be called with an empty record (example: Browsable Interface)
if not resource_instance:
return
current_serializer = fields.serializer
context = current_serializer.context
included_serializers = utils.get_included_serializers(current_serializer)
included_resources = copy.copy(included_resources)
included_resources = [inflection.underscore(value) for value in included_resources]
render_nested_as_attribute = json_api_settings.SERIALIZE_NESTED_SERIALIZERS_AS_ATTRIBUTE
for field_name, field in iter(fields.items()):
# Skip URL field
if field_name == api_settings.URL_FIELD_NAME:
continue
# Skip fields without relations
if not isinstance(
field, (relations.RelatedField, relations.ManyRelatedField, BaseSerializer)
):
continue
if isinstance(field, BaseSerializer) and render_nested_as_attribute:
continue
try:
included_resources.remove(field_name)
except ValueError:
# Skip fields not in requested included resources
# If no child field, directly continue with the next field
if field_name not in [node.split('.')[0] for node in included_resources]:
continue
relation_instance = cls.extract_relation_instance(
field, resource_instance
)
if isinstance(relation_instance, Manager):
relation_instance = relation_instance.all()
serializer_data = resource.get(field_name)
if isinstance(field, relations.ManyRelatedField):
serializer_class = included_serializers[field_name]
field = serializer_class(relation_instance, many=True, context=context)
serializer_data = field.data
if isinstance(field, relations.RelatedField):
if relation_instance is None or not serializer_data:
continue
many = field._kwargs.get('child_relation', None) is not None
if isinstance(field, ResourceRelatedField) and not many:
already_included = serializer_data['type'] in included_cache and \
serializer_data['id'] in included_cache[serializer_data['type']]
if already_included:
continue
serializer_class = included_serializers[field_name]
field = serializer_class(relation_instance, many=many, context=context)
serializer_data = field.data
new_included_resources = [key.replace('%s.' % field_name, '', 1)
for key in included_resources
if field_name == key.split('.')[0]]
if isinstance(field, ListSerializer):
serializer = field.child
relation_type = utils.get_resource_type_from_serializer(serializer)
relation_queryset = list(relation_instance)
if serializer_data:
for position in range(len(serializer_data)):
serializer_resource = serializer_data[position]
nested_resource_instance = relation_queryset[position]
resource_type = (
relation_type or
utils.get_resource_type_from_instance(nested_resource_instance)
)
serializer_fields = utils.get_serializer_fields(
serializer.__class__(
nested_resource_instance, context=serializer.context
)
)
new_item = cls.build_json_resource_obj(
serializer_fields,
serializer_resource,
nested_resource_instance,
resource_type,
getattr(serializer, '_poly_force_type_resolution', False)
)
included_cache[new_item['type']][new_item['id']] = \
utils.format_field_names(new_item)
cls.extract_included(
serializer_fields,
serializer_resource,
nested_resource_instance,
new_included_resources,
included_cache,
)
if isinstance(field, Serializer):
relation_type = utils.get_resource_type_from_serializer(field)
# Get the serializer fields
serializer_fields = utils.get_serializer_fields(field)
if serializer_data:
new_item = cls.build_json_resource_obj(
serializer_fields,
serializer_data,
relation_instance,
relation_type,
getattr(field, '_poly_force_type_resolution', False)
)
included_cache[new_item['type']][new_item['id']] = utils.format_field_names(
new_item
)
cls.extract_included(
serializer_fields,
serializer_data,
relation_instance,
new_included_resources,
included_cache,
)
@classmethod
def extract_meta(cls, serializer, resource):
"""
Gathers the data from serializer fields specified in meta_fields and adds it to
the meta object.
"""
if hasattr(serializer, 'child'):
meta = getattr(serializer.child, 'Meta', None)
else:
meta = getattr(serializer, 'Meta', None)
meta_fields = getattr(meta, 'meta_fields', [])
data = OrderedDict()
for field_name in meta_fields:
data.update({
field_name: resource.get(field_name)
})
return data
@classmethod
def extract_root_meta(cls, serializer, resource):
"""
Calls a `get_root_meta` function on a serializer, if it exists.
"""
many = False
if hasattr(serializer, 'child'):
many = True
serializer = serializer.child
data = {}
if getattr(serializer, 'get_root_meta', None):
json_api_meta = serializer.get_root_meta(resource, many)
assert isinstance(json_api_meta, dict), 'get_root_meta must return a dict'
data.update(json_api_meta)
return data
@classmethod
def build_json_resource_obj(cls, fields, resource, resource_instance, resource_name,
force_type_resolution=False):
"""
Builds the resource object (type, id, attributes) and extracts relationships.
"""
# Determine type from the instance if the underlying model is polymorphic
if force_type_resolution:
resource_name = utils.get_resource_type_from_instance(resource_instance)
resource_data = [
('type', resource_name),
('id', encoding.force_str(resource_instance.pk) if resource_instance else None),
('attributes', cls.extract_attributes(fields, resource)),
]
relationships = cls.extract_relationships(fields, resource, resource_instance)
if relationships:
resource_data.append(('relationships', relationships))
# Add 'self' link if field is present and valid
if api_settings.URL_FIELD_NAME in resource and \
isinstance(fields[api_settings.URL_FIELD_NAME], relations.RelatedField):
resource_data.append(('links', {'self': resource[api_settings.URL_FIELD_NAME]}))
return OrderedDict(resource_data)
def render_relationship_view(self, data, accepted_media_type=None, renderer_context=None):
# Special case for RelationshipView
view = renderer_context.get("view", None)
render_data = OrderedDict([
('data', data)
])
links = view.get_links()
if links:
render_data.update({'links': links}),
return super(JSONRenderer, self).render(
render_data, accepted_media_type, renderer_context
)
def render_errors(self, data, accepted_media_type=None, renderer_context=None):
return super(JSONRenderer, self).render(
utils.format_errors(data), accepted_media_type, renderer_context
)
def render(self, data, accepted_media_type=None, renderer_context=None):
renderer_context = renderer_context or {}
view = renderer_context.get("view", None)
request = renderer_context.get("request", None)
# Get the resource name.
resource_name = utils.get_resource_name(renderer_context)
# If this is an error response, skip the rest.
if resource_name == 'errors':
return self.render_errors(data, accepted_media_type, renderer_context)
# if response.status_code is 204 then the data to be rendered must
# be None
response = renderer_context.get('response', None)
if response is not None and response.status_code == 204:
return super(JSONRenderer, self).render(
None, accepted_media_type, renderer_context
)
from rest_framework_json_api.views import RelationshipView
if isinstance(view, RelationshipView):
return self.render_relationship_view(data, accepted_media_type, renderer_context)
# If `resource_name` is set to None then render default as the dev
# wants to build the output format manually.
if resource_name is None or resource_name is False:
return super(JSONRenderer, self).render(
data, accepted_media_type, renderer_context
)
json_api_data = data
# initialize json_api_meta with pagination meta or an empty dict
json_api_meta = data.get('meta', {}) if isinstance(data, dict) else {}
included_cache = defaultdict(dict)
if data and 'results' in data:
serializer_data = data["results"]
else:
serializer_data = data
serializer = getattr(serializer_data, 'serializer', None)
included_resources = utils.get_included_resources(request, serializer)
if serializer is not None:
# Extract root meta for any type of serializer
json_api_meta.update(self.extract_root_meta(serializer, serializer_data))
if getattr(serializer, 'many', False):
json_api_data = list()
for position in range(len(serializer_data)):
resource = serializer_data[position] # Get current resource
resource_instance = serializer.instance[position] # Get current instance
if isinstance(serializer.child, rest_framework_json_api.
serializers.PolymorphicModelSerializer):
resource_serializer_class = serializer.child.\
get_polymorphic_serializer_for_instance(resource_instance)(
context=serializer.child.context
)
else:
resource_serializer_class = serializer.child
fields = utils.get_serializer_fields(resource_serializer_class)
force_type_resolution = getattr(
resource_serializer_class, '_poly_force_type_resolution', False)
json_resource_obj = self.build_json_resource_obj(
fields, resource, resource_instance, resource_name, force_type_resolution
)
meta = self.extract_meta(serializer, resource)
if meta:
json_resource_obj.update({'meta': utils.format_field_names(meta)})
json_api_data.append(json_resource_obj)
self.extract_included(
fields, resource, resource_instance, included_resources, included_cache
)
else:
fields = utils.get_serializer_fields(serializer)
force_type_resolution = getattr(serializer, '_poly_force_type_resolution', False)
resource_instance = serializer.instance
json_api_data = self.build_json_resource_obj(
fields, serializer_data, resource_instance, resource_name, force_type_resolution
)
meta = self.extract_meta(serializer, serializer_data)
if meta:
json_api_data.update({'meta': utils.format_field_names(meta)})
self.extract_included(
fields, serializer_data, resource_instance, included_resources, included_cache
)
# Make sure we render data in a specific order
render_data = OrderedDict()
if isinstance(data, dict) and data.get('links'):
render_data['links'] = data.get('links')
# format the api root link list
if view.__class__ and view.__class__.__name__ == 'APIRoot':
render_data['data'] = None
render_data['links'] = json_api_data
else:
render_data['data'] = json_api_data
if included_cache:
if isinstance(json_api_data, list):
objects = json_api_data
else:
objects = [json_api_data]
for object in objects:
obj_type = object.get('type')
obj_id = object.get('id')
if obj_type in included_cache and \
obj_id in included_cache[obj_type]:
del included_cache[obj_type][obj_id]
if not included_cache[obj_type]:
del included_cache[obj_type]
if included_cache:
render_data['included'] = list()
for included_type in sorted(included_cache.keys()):
for included_id in sorted(included_cache[included_type].keys()):
render_data['included'].append(included_cache[included_type][included_id])
if json_api_meta:
render_data['meta'] = utils.format_field_names(json_api_meta)
return super(JSONRenderer, self).render(
render_data, accepted_media_type, renderer_context
)
