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mixins.py
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mixins.py
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from asgiref.sync import sync_to_async
from google.protobuf import empty_pb2
from rest_framework import serializers
from django_socio_grpc.protobuf.generation_plugin import (
FilterGenerationPlugin,
PaginationGenerationPlugin,
ResponseAsListGenerationPlugin,
)
from .decorators import grpc_action
from .grpc_actions.actions import GRPCActionMixin
from .grpc_actions.placeholders import (
FnPlaceholder,
LookupField,
SelfSerializer,
StrTemplatePlaceholder,
)
from .grpc_actions.utils import get_serializer_base_name
from .settings import grpc_settings
from .utils.constants import DEFAULT_LIST_FIELD_NAME, PARTIAL_UPDATE_FIELD_NAME, REQUEST_SUFFIX
############################################################
# Synchronous mixins #
############################################################
class CreateModelMixin(GRPCActionMixin):
@grpc_action(request=SelfSerializer, response=SelfSerializer)
def Create(self, request, context):
"""
Create a model instance.
The request should be a proto message of ``serializer.Meta.proto_class``.
If an object is created this returns a proto message of
``serializer.Meta.proto_class``.
"""
serializer = self.get_serializer(message=request)
serializer.is_valid(raise_exception=True)
self.perform_create(serializer)
return serializer.message
def perform_create(self, serializer):
"""Save a new object instance."""
serializer.save()
@staticmethod
def get_default_method(model_name):
return {
"Create": {
"request": {"is_stream": False, "message": model_name},
"response": {"is_stream": False, "message": model_name},
},
}
@staticmethod
def get_default_message(model_name, fields="__all__"):
return {
model_name: fields,
}
class ListModelMixin(GRPCActionMixin):
@grpc_action(
request=[],
# DEPRECATED - AM - 23/02/2024 - request_name only keept because will generate emptyMessage. Need to be removed in version 1.0.0
request_name=StrTemplatePlaceholder(
f"{{}}List{REQUEST_SUFFIX}", get_serializer_base_name
),
response=SelfSerializer,
use_generation_plugins=[
ResponseAsListGenerationPlugin(),
FilterGenerationPlugin(display_warning_message=False),
PaginationGenerationPlugin(display_warning_message=False),
],
)
def List(self, request, context):
"""
List a queryset. This sends a message array of
``serializer.Meta.proto_class`` to the client.
.. note::
This is a server streaming RPC.
"""
queryset = self.filter_queryset(self.get_queryset())
page = self.paginate_queryset(queryset)
if page is not None:
serializer = self.get_serializer(page, many=True)
if hasattr(serializer.message, "count"):
serializer.message.count = self.paginator.page.paginator.count
return serializer.message
else:
serializer = self.get_serializer(queryset, many=True)
return serializer.message
@staticmethod
def get_default_method(model_name):
return {
"List": {
"request": {"is_stream": False, "message": f"{model_name}ListRequest"},
"response": {"is_stream": False, "message": f"{model_name}ListResponse"},
},
}
@staticmethod
def get_default_message(
model_name, fields=None, pagination=None, response_field_name=DEFAULT_LIST_FIELD_NAME
):
if fields is None:
fields = []
# If user let default choose for pagination we check if there is a default pagination class setted
if pagination is None:
pagination = grpc_settings.DEFAULT_PAGINATION_CLASS is not None
response_fields = [f"__custom__repeated {model_name}__{response_field_name}__"]
if pagination:
response_fields += ["__custom__int32__count__"]
return {
f"{model_name}ListRequest": fields,
f"{model_name}ListResponse": response_fields,
}
class StreamModelMixin(GRPCActionMixin):
@grpc_action(
request=[],
request_name=StrTemplatePlaceholder(
f"{{}}Stream{REQUEST_SUFFIX}", get_serializer_base_name
),
response=SelfSerializer,
response_stream=True,
use_generation_plugins=[
FilterGenerationPlugin(display_warning_message=False),
PaginationGenerationPlugin(display_warning_message=False),
],
)
def Stream(self, request, context):
"""
List a queryset. This sends a sequence of messages of
``serializer.Meta.proto_class`` to the client.
.. note::
This is a server streaming RPC.
"""
queryset = self.filter_queryset(self.get_queryset())
page = self.paginate_queryset(queryset)
if page is not None:
serializer = self.get_serializer(page, many=True, stream=True)
else:
serializer = self.get_serializer(queryset, many=True, stream=True)
yield from serializer.message
@staticmethod
def get_default_method(model_name):
return {
"Stream": {
"request": {"is_stream": False, "message": f"{model_name}StreamRequest"},
"response": {"is_stream": True, "message": model_name},
},
}
@staticmethod
def get_default_message(model_name, fields=None):
if fields is None:
fields = []
return {
f"{model_name}StreamRequest": fields,
}
class RetrieveModelMixin(GRPCActionMixin):
@grpc_action(
request=LookupField,
request_name=StrTemplatePlaceholder(
f"{{}}Retrieve{REQUEST_SUFFIX}", get_serializer_base_name
),
response=SelfSerializer,
)
def Retrieve(self, request, context):
"""
Retrieve a model instance.
The request have to include a field corresponding to
``lookup_request_field``. If an object can be retrieved this returns
a proto message of ``serializer.Meta.proto_class``.
"""
instance = self.get_object()
serializer = self.get_serializer(instance)
return serializer.message
@staticmethod
def get_default_method(model_name):
return {
"Retrieve": {
"request": {"is_stream": False, "message": f"{model_name}RetrieveRequest"},
"response": {"is_stream": False, "message": model_name},
},
}
@staticmethod
def get_default_message(model_name, fields="__pk__"):
return {
f"{model_name}RetrieveRequest": fields,
}
class UpdateModelMixin(GRPCActionMixin):
@grpc_action(request=SelfSerializer, response=SelfSerializer)
def Update(self, request, context):
"""
Update a model instance.
The request should be a proto message of ``serializer.Meta.proto_class``.
If an object is updated this returns a proto message of
``serializer.Meta.proto_class``.
"""
instance = self.get_object()
serializer = self.get_serializer(instance, message=request)
serializer.is_valid(raise_exception=True)
self.perform_update(serializer)
if getattr(instance, "_prefetched_objects_cache", None):
# If 'prefetch_related' has been applied to a queryset, we need to
# forcibly invalidate the prefetch cache on the instance.
instance._prefetched_objects_cache = {}
return serializer.message
def perform_update(self, serializer):
"""Save an existing object instance."""
serializer.save()
@staticmethod
def get_default_method(model_name):
return {
"Update": {
"request": {"is_stream": False, "message": model_name},
"response": {"is_stream": False, "message": model_name},
},
}
@staticmethod
def get_default_message(model_name, fields="__all__"):
return {
f"{model_name}UpdateRequest": fields,
}
def _get_partial_update_request(service):
serializer_class = service.get_serializer_class()
class PartialUpdateMetaClass(serializers.SerializerMetaclass):
"""
This metaclass exists so we can set the PARTIAL_UPDATE_FIELD_NAME variable as an attribute name of PartialUpdateRequest.
This can be replaced by just declaring in PartialUpdateRequest:
_partial_update_fields = serializers.ListField(child=serializers.CharField())
but this would not be dynamic if a constant changes or if we want it to be configurable in settings in the future.
This metaclass should inherit from DRF SerializerMetaclass as serializer has it's own metaclass to add _declared_fields attribute
Using PartialUpdateRequest.setattr is not enough as _declared_fields is done in metaclass so all fields should be declared before
"""
def __new__(cls, name, bases, attrs):
attrs[PARTIAL_UPDATE_FIELD_NAME] = serializers.ListField(
child=serializers.CharField()
)
return super().__new__(cls, name, bases, attrs)
class PartialUpdateRequest(serializer_class, metaclass=PartialUpdateMetaClass):
class Meta(serializer_class.Meta): ...
# INFO - L.G. - 19/06/2022 - extra field needs to be appended to
# the serializer.
if (fields := getattr(PartialUpdateRequest.Meta, "fields", None)) and not isinstance(
fields, str
):
PartialUpdateRequest.Meta.fields = (*fields, PARTIAL_UPDATE_FIELD_NAME)
return PartialUpdateRequest
class PartialUpdateModelMixin(GRPCActionMixin):
@grpc_action(
request=FnPlaceholder(_get_partial_update_request),
request_name=StrTemplatePlaceholder(
f"{{}}PartialUpdate{REQUEST_SUFFIX}", get_serializer_base_name
),
response=SelfSerializer,
)
def PartialUpdate(self, request, context):
"""
Partial update a model instance.
Performs a partial update on the given PARTIAL_UPDATE_FIELD_NAME(`_partial_update_fields`).
"""
instance = self.get_object()
# INFO - L.G. - 11/07/2022 - We use the data parameter instead of message
# because we handle a dict not a grpc message.
serializer = self.get_serializer(instance, message=request, partial=True)
serializer.is_valid(raise_exception=True)
self.perform_partial_update(serializer)
if getattr(instance, "_prefetched_objects_cache", None):
# If 'prefetch_related' has been applied to a queryset, we need to
# forcibly invalidate the prefetch cache on the instance.
instance._prefetched_objects_cache = {}
return serializer.message
def perform_partial_update(self, serializer):
"""Save an existing object instance."""
serializer.save()
@staticmethod
def get_default_method(model_name):
return {
"Update": {
"request": {"is_stream": False, "message": model_name},
"response": {"is_stream": False, "message": model_name},
},
}
@staticmethod
def get_default_message(model_name, fields="__all__"):
return {
f"{model_name}PartialUpdateRequest": fields,
}
class DestroyModelMixin(GRPCActionMixin):
@grpc_action(
request=LookupField,
request_name=StrTemplatePlaceholder(
f"{{}}Destroy{REQUEST_SUFFIX}", get_serializer_base_name
),
response=[],
)
def Destroy(self, request, context):
"""
Destroy a model instance.
The request have to include a field corresponding to
``lookup_request_field``. If an object is deleted this returns
a proto message of ``google.protobuf.empty_pb2.Empty``.
"""
instance = self.get_object()
self.perform_destroy(instance)
return empty_pb2.Empty()
def perform_destroy(self, instance):
"""Delete an object instance."""
instance.delete()
@staticmethod
def get_default_method(model_name):
return {
"Destroy": {
"request": {"is_stream": False, "message": f"{model_name}DestroyRequest"},
"response": {"is_stream": False, "message": "google.protobuf.Empty"},
},
}
@staticmethod
def get_default_message(model_name, fields="__pk__"):
return {
f"{model_name}DestroyRequest": fields,
}
############################################################
# Asynchronous mixins #
############################################################
class AsyncCreateModelMixin(CreateModelMixin):
async def Create(self, request, context):
"""
Create a model instance.
The request should be a proto message of ``serializer.Meta.proto_class``.
If an object is created this returns a proto message of
``serializer.Meta.proto_class``.
"""
serializer = await self.aget_serializer(message=request)
await sync_to_async(serializer.is_valid)(raise_exception=True)
await self.aperform_create(serializer)
return await serializer.amessage
async def aperform_create(self, serializer):
"""Save a new object instance."""
await sync_to_async(serializer.save)()
class AsyncListModelMixin(ListModelMixin):
async def List(self, request, context):
"""
List a queryset. This sends a message array of
``serializer.Meta.proto_class`` to the client.
.. note::
This is a server streaming RPC.
"""
queryset = await sync_to_async(self.get_queryset)()
queryset = await self.afilter_queryset(queryset)
page = await sync_to_async(self.paginate_queryset)(queryset)
if page is not None:
serializer = await self.aget_serializer(page, many=True)
message = await serializer.amessage
if hasattr(message, "count"):
message.count = self.paginator.page.paginator.count
return message
else:
serializer = await self.aget_serializer(queryset, many=True)
return await serializer.amessage
class AsyncStreamModelMixin(StreamModelMixin):
async def _get_list_data(self):
queryset = await sync_to_async(self.get_queryset)()
queryset = await self.afilter_queryset(queryset)
page = await sync_to_async(self.paginate_queryset)(queryset)
if page is not None:
serializer = await self.aget_serializer(page, many=True, stream=True)
else:
serializer = await self.aget_serializer(queryset, many=True, stream=True)
return await serializer.amessage
async def Stream(self, request, context):
"""
List a queryset. This sends a sequence of messages of
``serializer.Meta.proto_class`` to the client.
.. note::
This is a server streaming RPC.
"""
messages = await self._get_list_data()
for message in messages:
yield message
class AsyncRetrieveModelMixin(RetrieveModelMixin):
async def Retrieve(self, request, context):
"""
Retrieve a model instance.
The request have to include a field corresponding to
``lookup_request_field``. If an object can be retrieved this returns
a proto message of ``serializer.Meta.proto_class``.
"""
instance = await self.aget_object()
serializer = await self.aget_serializer(instance)
return await serializer.amessage
class AsyncUpdateModelMixin(UpdateModelMixin):
async def Update(self, request, context):
"""
Update a model instance.
The request should be a proto message of ``serializer.Meta.proto_class``.
If an object is updated this returns a proto message of
``serializer.Meta.proto_class``.
"""
instance = await self.aget_object()
serializer = await self.aget_serializer(instance, message=request)
await sync_to_async(serializer.is_valid)(raise_exception=True)
await self.aperform_update(serializer)
if getattr(instance, "_prefetched_objects_cache", None):
# If 'prefetch_related' has been applied to a queryset, we need to
# forcibly invalidate the prefetch cache on the instance.
instance._prefetched_objects_cache = {}
return await serializer.amessage
async def aperform_update(self, serializer):
"""Save an existing object instance."""
await sync_to_async(serializer.save)()
class AsyncPartialUpdateModelMixin(PartialUpdateModelMixin):
async def PartialUpdate(self, request, context):
"""
Partial update a model instance.
Performs a partial update on the given PARTIAL_UPDATE_FIELD_NAME(`_partial_update_fields`).
"""
instance = await self.aget_object()
# INFO - L.G. - 11/07/2022 - We use the data parameter instead of message
# because we handle a dict not a grpc message.
serializer = await self.aget_serializer(instance, message=request, partial=True)
await sync_to_async(serializer.is_valid)(raise_exception=True)
await self.aperform_partial_update(serializer)
if getattr(instance, "_prefetched_objects_cache", None):
# If 'prefetch_related' has been applied to a queryset, we need to
# forcibly invalidate the prefetch cache on the instance.
instance._prefetched_objects_cache = {}
return await serializer.amessage
async def aperform_partial_update(self, serializer):
"""Save an existing object instance."""
await sync_to_async(serializer.save)()
class AsyncDestroyModelMixin(DestroyModelMixin):
async def Destroy(self, request, context):
"""
Destroy a model instance.
The request have to include a field corresponding to
``lookup_request_field``. If an object is deleted this returns
a proto message of ``google.protobuf.empty_pb2.Empty``.
"""
instance = await self.aget_object()
await self.aperform_destroy(instance)
return empty_pb2.Empty()
async def aperform_destroy(self, instance):
"""Delete an object instance."""
await sync_to_async(instance.delete)()
############################################################
# Default grpc messages #
############################################################
def get_default_grpc_methods(model_name):
"""
return the default grpc methods generated for a django model.
"""
return {
**ListModelMixin.get_default_method(model_name),
**CreateModelMixin.get_default_method(model_name),
**RetrieveModelMixin.get_default_method(model_name),
**UpdateModelMixin.get_default_method(model_name),
**DestroyModelMixin.get_default_method(model_name),
}
def get_default_grpc_messages(model_name):
"""
return the default protobuff message we want to generate
"""
return {
**CreateModelMixin.get_default_message(model_name),
**ListModelMixin.get_default_message(model_name),
**RetrieveModelMixin.get_default_message(model_name),
**DestroyModelMixin.get_default_message(model_name),
}