"""This module contains custom DRF metadata classes."""
from collections import OrderedDict
from django.utils.encoding import force_text
from rest_framework.fields import empty
from rest_framework.metadata import SimpleMetadata
from rest_framework.serializers import ListSerializer, ModelSerializer
from dynamic_rest.fields import DynamicRelationField
class DynamicMetadata(SimpleMetadata):
"""A subclass of SimpleMetadata.
Adds `properties` and `features` to the metdata.
"""
def determine_actions(self, request, view):
"""Prevent displaying action-specific details."""
return None
def determine_metadata(self, request, view):
"""Adds `properties` and `features` to the metadata response."""
metadata = super(
DynamicMetadata,
self).determine_metadata(
request,
view)
metadata['features'] = getattr(view, 'features', [])
if hasattr(view, 'get_serializer'):
serializer = view.get_serializer(dynamic=False)
if hasattr(serializer, 'get_name'):
metadata['resource_name'] = serializer.get_name()
if hasattr(serializer, 'get_plural_name'):
metadata['resource_name_plural'] = serializer.get_plural_name()
metadata['properties'] = self.get_serializer_info(serializer)
return metadata
def get_field_info(self, field):
"""Adds `related_to` and `nullable` to the metadata response."""
field_info = OrderedDict()
for attr in ('required', 'read_only', 'default', 'label'):
field_info[attr] = getattr(field, attr)
if field_info['default'] is empty:
field_info['default'] = None
if hasattr(field, 'immutable'):
field_info['immutable'] = field.immutable
field_info['nullable'] = field.allow_null
if hasattr(field, 'choices'):
field_info['choices'] = [
{
'value': choice_value,
'display_name': force_text(choice_name, strings_only=True)
}
for choice_value, choice_name in field.choices.items()
]
many = False
if isinstance(field, DynamicRelationField):
field = field.serializer
if isinstance(field, ListSerializer):
field = field.child
many = True
if isinstance(field, ModelSerializer):
type = 'many' if many else 'one'
field_info['related_to'] = field.get_plural_name()
else:
type = self.label_lookup[field]
field_info['type'] = type
return field_info
