renderers.py

"""
Renderers
"""
import copy
from collections import defaultdict
from collections.abc import Iterable

import inflection
from django.db.models import Manager
from django.template import loader
from django.utils.encoding import force_str
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 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,
)


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 = {}
        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 utils.is_relationship_field(field):
                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 = {}

        # 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 utils.is_relationship_field(field):
                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()
                )

                relation_data = [
                    {"type": relation_type, "id": force_str(related_object.pk)}
                    for related_object in relation_queryset
                ]
                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, f"{source}_id", field.parent
                )
                if not resolved:
                    continue
                relation_id = relation if resource.get(field_name) else None
                relation_data = {"data": None}
                if relation_id is not None:
                    relation_data["data"] = {
                        "type": relation_type,
                        "id": force_str(relation_id),
                    }

                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(
                        {
                            "type": nested_resource_instance_type,
                            "id": force_str(nested_resource_instance.pk),
                        }
                    )
                data.update(
                    {
                        field_name: {
                            "data": relation_data,
                            "meta": {"count": len(relation_data)},
                        }
                    }
                )
                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 = getattr(
            current_serializer, "included_serializers", dict()
        )
        included_resources = copy.copy(included_resources)
        included_resources = [
            inflection.underscore(value) for value in included_resources
        ]

        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 utils.is_relationship_field(field):
                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(f"{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,
                            serializer,
                            getattr(serializer, "_poly_force_type_resolution", False),
                        )
                        included_cache[new_item["type"]][new_item["id"]] = 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,
                        field,
                        getattr(field, "_poly_force_type_resolution", False),
                    )
                    included_cache[new_item["type"]][new_item["id"]] = 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 = {}
        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,
        serializer,
        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_id = force_str(resource_instance.pk) if resource_instance else None
        resource_data = {
            "type": resource_name,
            "id": resource_id,
            "attributes": cls.extract_attributes(fields, resource),
        }
        relationships = cls.extract_relationships(fields, resource, resource_instance)
        if relationships:
            resource_data["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["links"] = {"self": resource[api_settings.URL_FIELD_NAME]}

        meta = cls.extract_meta(serializer, resource)
        if meta:
            resource_data["meta"] = utils.format_field_names(meta)

        return 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 = {"data": data}
        links = view.get_links()
        if links:
            render_data.update({"links": links}),
        return super().render(render_data, accepted_media_type, renderer_context)

    def render_errors(self, data, accepted_media_type=None, renderer_context=None):
        return super().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().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().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,
                        serializer,
                        force_type_resolution,
                    )
                    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,
                    serializer,
                    force_type_resolution,
                )

                self.extract_included(
                    fields,
                    serializer_data,
                    resource_instance,
                    included_resources,
                    included_cache,
                )

        # Make sure we render data in a specific order
        render_data = {}

        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().render(render_data, accepted_media_type, renderer_context)


class BrowsableAPIRenderer(renderers.BrowsableAPIRenderer):
    template = "rest_framework_json_api/api.html"
    includes_template = "rest_framework_json_api/includes.html"

    def get_context(self, data, accepted_media_type, renderer_context):
        context = super().get_context(data, accepted_media_type, renderer_context)
        view = renderer_context["view"]

        context["includes_form"] = self.get_includes_form(view)

        if "included" not in context:       # Adds the included field if it is not present
            context["included"] = []

        return context


    @classmethod
    def _get_included_serializers(cls, serializer, prefix="", already_seen=None):
        if not already_seen:
            already_seen = set()

        if serializer in already_seen:
            return []

        included_serializers = []
        already_seen.add(serializer)

        for include, included_serializer in getattr(
            serializer, "included_serializers", dict()
        ).items():
            included_serializers.append(f"{prefix}{include}")
            included_serializers.extend(
                cls._get_included_serializers(
                    included_serializer,
                    f"{prefix}{include}.",
                    already_seen=already_seen,
                )
            )

        return included_serializers

    def get_includes_form(self, view):
        try:
            if "related_field" in view.kwargs:
                serializer_class = view.get_related_serializer_class()
            else:
                serializer_class = view.get_serializer_class()
        except AttributeError:
            return

        if not hasattr(serializer_class, "included_serializers"):
            return

        template = loader.get_template(self.includes_template)
        context = {"elements": self._get_included_serializers(serializer_class)}
        return template.render(context)