Added JSON:API OPTIONS metadata handler

README.rst

@@ -130,6 +130,7 @@ override ``settings.REST_FRAMEWORK``::
             'rest_framework_json_api.renderers.JSONRenderer',
             'rest_framework.renderers.BrowsableAPIRenderer',
         ),
+        'DEFAULT_METADATA_CLASS': 'rest_framework_json_api.metadata.JSONAPIMetadata',
     }
 
 If ``PAGINATE_BY`` is set the renderer will return a ``meta`` object with

rest_framework_json_api/metadata.py

@@ -0,0 +1,119 @@
+from collections import OrderedDict
+from django.db.models.fields import related
+from django.http import Http404
+from django.utils.encoding import force_text
+from rest_framework import serializers
+from rest_framework.exceptions import PermissionDenied
+from rest_framework.metadata import BaseMetadata, SimpleMetadata
+from rest_framework.request import clone_request
+from rest_framework.utils.field_mapping import ClassLookupDict
+from rest_framework_json_api import exceptions
+from rest_framework_json_api.utils import format_relation_name, get_related_resource_type
+
+
+class JSONAPIMetadata(SimpleMetadata):
+    """
+    This is the JSON:API metadata implementation.
+    It returns an ad-hoc set of information about the view.
+    There are not any formalized standards for `OPTIONS` responses
+    for us to base this on.
+    """
+    type_lookup = ClassLookupDict({
+        serializers.HyperlinkedIdentityField: 'Relationship',
+        serializers.HyperlinkedRelatedField: 'Relationship',
+        serializers.BooleanField: 'Boolean',
+        serializers.NullBooleanField: 'Boolean',
+        serializers.CharField: 'String',
+        serializers.URLField: 'URL',
+        serializers.EmailField: 'Email',
+        serializers.RegexField: 'Regex',
+        serializers.SlugField: 'Slug',
+        serializers.IntegerField: 'Integer',
+        serializers.FloatField: 'Float',
+        serializers.DecimalField: 'Decimal',
+        serializers.DateField: 'Date',
+        serializers.DateTimeField: 'DateTime',
+        serializers.TimeField: 'Time',
+        serializers.ChoiceField: 'Choice',
+        serializers.MultipleChoiceField: 'MultipleChoice',
+        serializers.FileField: 'File',
+        serializers.ImageField: 'Image',
+        serializers.ListField: 'List',
+        serializers.DictField: 'Dict',
+        serializers.Serializer: 'Serializer',
+    })
+
+    relation_type_lookup = ClassLookupDict({
+        related.ReverseManyRelatedObjectsDescriptor: 'ManyToMany',
+        related.ForeignRelatedObjectsDescriptor: 'OneToMany',
+        related.ReverseSingleRelatedObjectDescriptor: 'ManyToOne',
+    })
+
+    def determine_metadata(self, request, view):
+        metadata = OrderedDict()
+        metadata['name'] = view.get_view_name()
+        metadata['description'] = view.get_view_description()
+        metadata['renders'] = [renderer.media_type for renderer in view.renderer_classes]
+        metadata['parses'] = [parser.media_type for parser in view.parser_classes]
+        metadata['allowed_methods'] = view.allowed_methods
+        if hasattr(view, 'get_serializer'):
+            actions = self.determine_actions(request, view)
+            if actions:
+                metadata['actions'] = actions
+        return metadata
+
+    def get_serializer_info(self, serializer):
+        """
+        Given an instance of a serializer, return a dictionary of metadata
+        about its fields.
+        """
+        if hasattr(serializer, 'child'):
+            # If this is a `ListSerializer` then we want to examine the
+            # underlying child serializer instance instead.
+            serializer = serializer.child
+        return OrderedDict([
+                               (field_name, self.get_field_info(field, serializer))
+                               for field_name, field in serializer.fields.items()
+                               ])
+
+    def get_field_info(self, field, serializer):
+        """
+        Given an instance of a serializer field, return a dictionary
+        of metadata about it.
+        """
+        field_info = OrderedDict()
+
+        if isinstance(field, serializers.ManyRelatedField):
+            field_info['type'] = self.type_lookup[field.child_relation]
+        else:
+            field_info['type'] = self.type_lookup[field]
+
+        serializer_model = getattr(serializer.Meta, 'model')
+        try:
+            field_info['relationship_type'] = self.relation_type_lookup[getattr(serializer_model, field.field_name)]
+        except KeyError:
+            pass
+        except AttributeError:
+            pass
+        else:
+            field_info['relationship_resource'] = get_related_resource_type(field)
+
+        field_info['required'] = getattr(field, 'required', False)
+
+        attrs = [
+            'read_only', 'write_only', 'label', 'help_text',
+            'min_length', 'max_length',
+            'min_value', 'max_value', 'initial'
+        ]
+
+        for attr in attrs:
+            value = getattr(field, attr, None)
+            if value is not None and value != '':
+                field_info[attr] = force_text(value, strings_only=True)
+
+        if getattr(field, 'child', None):
+            field_info['child'] = self.get_field_info(field.child, field.child.serializer)
+        elif getattr(field, 'fields', None):
+            field_info['children'] = self.get_serializer_info(field)
+
+        return field_info