import inspect
import logging
from django.utils.encoding import force_text
from rest_framework import serializers
from rest_framework.utils import encoders, json
from .. import openapi
from ..utils import is_list_view
#: Sentinel value that inspectors must return to signal that they do not know how to handle an object
NotHandled = object()
logger = logging.getLogger(__name__)
class BaseInspector(object):
def __init__(self, view, path, method, components, request):
"""
:param view: the view associated with this endpoint
:param str path: the path component of the operation URL
:param str method: the http method of the operation
:param openapi.ReferenceResolver components: referenceable components
:param Request request: the request made against the schema view; can be None
"""
self.view = view
self.path = path
self.method = method
self.components = components
self.request = request
[docs] def process_result(self, result, method_name, obj, **kwargs):
"""After an inspector handles an object (i.e. returns a value other than :data:`.NotHandled`), all inspectors
that were probed get the chance to alter the result, in reverse order. The inspector that handled the object
is the first to receive a ``process_result`` call with the object it just returned.
This behaviour is similar to the Django request/response middleware processing.
If this inspector has no post-processing to do, it should just ``return result`` (the default implementation).
:param result: the return value of the winning inspector, or ``None`` if no inspector handled the object
:param str method_name: name of the method that was called on the inspector
:param obj: first argument passed to inspector method
:param kwargs: additional arguments passed to inspector method
:return:
"""
return result
[docs] def probe_inspectors(self, inspectors, method_name, obj, initkwargs=None, **kwargs):
"""Probe a list of inspectors with a given object. The first inspector in the list to return a value that
is not :data:`.NotHandled` wins.
:param list[type[BaseInspector]] inspectors: list of inspectors to probe
:param str method_name: name of the target method on the inspector
:param obj: first argument to inspector method
:param dict initkwargs: extra kwargs for instantiating inspector class
:param kwargs: additional arguments to inspector method
:return: the return value of the winning inspector, or ``None`` if no inspector handled the object
"""
initkwargs = initkwargs or {}
tried_inspectors = []
for inspector in inspectors:
assert inspect.isclass(inspector), "inspector must be a class, not an object"
assert issubclass(inspector, BaseInspector), "inspectors must subclass BaseInspector"
inspector = inspector(self.view, self.path, self.method, self.components, self.request, **initkwargs)
tried_inspectors.append(inspector)
method = getattr(inspector, method_name, None)
if method is None:
continue
result = method(obj, **kwargs)
if result is not NotHandled:
break
else: # pragma: no cover
logger.warning("%s ignored because no inspector in %s handled it (operation: %s)",
obj, inspectors, method_name)
result = None
for inspector in reversed(tried_inspectors):
result = inspector.process_result(result, method_name, obj, **kwargs)
return result
class PaginatorInspector(BaseInspector):
"""Base inspector for paginators.
Responisble for determining extra query parameters and response structure added by given paginators.
"""
[docs] def get_paginator_parameters(self, paginator):
"""Get the pagination parameters for a single paginator **instance**.
Should return :data:`.NotHandled` if this inspector does not know how to handle the given `paginator`.
:param BasePagination paginator: the paginator
:rtype: list[openapi.Parameter]
"""
return NotHandled
[docs] def get_paginated_response(self, paginator, response_schema):
"""Add appropriate paging fields to a response :class:`.Schema`.
Should return :data:`.NotHandled` if this inspector does not know how to handle the given `paginator`.
:param BasePagination paginator: the paginator
:param openapi.Schema response_schema: the response schema that must be paged.
:rtype: openapi.Schema
"""
return NotHandled
class FilterInspector(BaseInspector):
"""Base inspector for filter backends.
Responsible for determining extra query parameters added by given filter backends.
"""
[docs] def get_filter_parameters(self, filter_backend):
"""Get the filter parameters for a single filter backend **instance**.
Should return :data:`.NotHandled` if this inspector does not know how to handle the given `filter_backend`.
:param BaseFilterBackend filter_backend: the filter backend
:rtype: list[openapi.Parameter]
"""
return NotHandled
class FieldInspector(BaseInspector):
"""Base inspector for serializers and serializer fields. """
def __init__(self, view, path, method, components, request, field_inspectors):
super(FieldInspector, self).__init__(view, path, method, components, request)
self.field_inspectors = field_inspectors
[docs] def field_to_swagger_object(self, field, swagger_object_type, use_references, **kwargs):
"""Convert a drf Serializer or Field instance into a Swagger object.
Should return :data:`.NotHandled` if this inspector does not know how to handle the given `field`.
:param rest_framework.serializers.Field field: the source field
:param type[openapi.SwaggerDict] swagger_object_type: should be one of Schema, Parameter, Items
:param bool use_references: if False, forces all objects to be declared inline
instead of by referencing other components
:param kwargs: extra attributes for constructing the object;
if swagger_object_type is Parameter, ``name`` and ``in_`` should be provided
:return: the swagger object
:rtype: openapi.Parameter,openapi.Items,openapi.Schema,openapi.SchemaRef
"""
return NotHandled
[docs] def probe_field_inspectors(self, field, swagger_object_type, use_references, **kwargs):
"""Helper method for recursively probing `field_inspectors` to handle a given field.
All arguments are the same as :meth:`.field_to_swagger_object`.
:rtype: openapi.Parameter,openapi.Items,openapi.Schema,openapi.SchemaRef
"""
return self.probe_inspectors(
self.field_inspectors, 'field_to_swagger_object', field, {'field_inspectors': self.field_inspectors},
swagger_object_type=swagger_object_type, use_references=use_references, **kwargs
)
[docs] def _get_partial_types(self, field, swagger_object_type, use_references, **kwargs):
"""Helper method to extract generic information from a field and return a partial constructor for the
appropriate openapi object.
All arguments are the same as :meth:`.field_to_swagger_object`.
The return value is a tuple consisting of:
* a function for constructing objects of `swagger_object_type`; its prototype is: ::
def SwaggerType(existing_object=None, **instance_kwargs):
This function creates an instance of `swagger_object_type`, passing the following attributes to its init,
in order of precedence:
- arguments specified by the ``kwargs`` parameter of :meth:`._get_partial_types`
- ``instance_kwargs`` passed to the constructor function
- ``title``, ``description``, ``required`` and ``default`` inferred from the field,
where appropriate
If ``existing_object`` is not ``None``, it is updated instead of creating a new object.
* a type that should be used for child objects if `field` is of an array type. This can currently have two
values:
- :class:`.Schema` if `swagger_object_type` is :class:`.Schema`
- :class:`.Items` if `swagger_object_type` is :class:`.Parameter` or :class:`.Items`
:rtype: tuple[callable,(type[openapi.Schema],type[openapi.Items])]
"""
assert swagger_object_type in (openapi.Schema, openapi.Parameter, openapi.Items)
assert not isinstance(field, openapi.SwaggerDict), "passed field is already a SwaggerDict object"
title = force_text(field.label) if field.label else None
title = title if swagger_object_type == openapi.Schema else None # only Schema has title
description = force_text(field.help_text) if field.help_text else None
description = description if swagger_object_type != openapi.Items else None # Items has no description either
def SwaggerType(existing_object=None, **instance_kwargs):
if 'required' not in instance_kwargs and swagger_object_type == openapi.Parameter:
instance_kwargs['required'] = field.required
if 'default' not in instance_kwargs and swagger_object_type != openapi.Items:
default = getattr(field, 'default', serializers.empty)
if default is not serializers.empty:
if callable(default):
try:
if hasattr(default, 'set_context'):
default.set_context(field)
default = default()
except Exception: # pragma: no cover
logger.warning("default for %s is callable but it raised an exception when "
"called; 'default' field will not be added to schema", field, exc_info=True)
default = None
if default is not None:
try:
default = field.to_representation(default)
# JSON roundtrip ensures that the value is valid JSON;
# for example, sets and tuples get transformed into lists
default = json.loads(json.dumps(default, cls=encoders.JSONEncoder))
except Exception: # pragma: no cover
logger.warning("'default' on schema for %s will not be set because "
"to_representation raised an exception", field, exc_info=True)
default = None
if default is not None:
instance_kwargs['default'] = default
instance_kwargs.setdefault('title', title)
instance_kwargs.setdefault('description', description)
instance_kwargs.update(kwargs)
if existing_object is not None:
assert isinstance(existing_object, swagger_object_type)
for attr, val in sorted(instance_kwargs.items()):
setattr(existing_object, attr, val)
return existing_object
return swagger_object_type(**instance_kwargs)
# arrays in Schema have Schema elements, arrays in Parameter and Items have Items elements
child_swagger_type = openapi.Schema if swagger_object_type == openapi.Schema else openapi.Items
return SwaggerType, child_swagger_type
class SerializerInspector(FieldInspector):
[docs] def get_schema(self, serializer):
"""Convert a DRF Serializer instance to an :class:`.openapi.Schema`.
Should return :data:`.NotHandled` if this inspector does not know how to handle the given `serializer`.
:param serializers.BaseSerializer serializer: the ``Serializer`` instance
:rtype: openapi.Schema
"""
return NotHandled
[docs] def get_request_parameters(self, serializer, in_):
"""Convert a DRF serializer into a list of :class:`.Parameter`\ s.
Should return :data:`.NotHandled` if this inspector does not know how to handle the given `serializer`.
:param serializers.BaseSerializer serializer: the ``Serializer`` instance
:param str in_: the location of the parameters, one of the `openapi.IN_*` constants
:rtype: list[openapi.Parameter]
"""
return NotHandled
class ViewInspector(BaseInspector):
body_methods = ('PUT', 'PATCH', 'POST') #: methods that are allowed to have a request body
# real values set in __init__ to prevent import errors
field_inspectors = [] #:
filter_inspectors = [] #:
paginator_inspectors = [] #:
def __init__(self, view, path, method, components, request, overrides):
"""
Inspector class responsible for providing :class:`.Operation` definitions given a view, path and method.
:param dict overrides: manual overrides as passed to :func:`@swagger_auto_schema <.swagger_auto_schema>`
"""
super(ViewInspector, self).__init__(view, path, method, components, request)
self.overrides = overrides
self._prepend_inspector_overrides('field_inspectors')
self._prepend_inspector_overrides('filter_inspectors')
self._prepend_inspector_overrides('paginator_inspectors')
[docs] def _prepend_inspector_overrides(self, inspectors):
extra_inspectors = self.overrides.get(inspectors, None)
if extra_inspectors:
default_inspectors = [insp for insp in getattr(self, inspectors) if insp not in extra_inspectors]
setattr(self, inspectors, extra_inspectors + default_inspectors)
[docs] def get_operation(self, operation_keys):
"""Get an :class:`.Operation` for the given API endpoint (path, method).
This includes query, body parameters and response schemas.
:param tuple[str] operation_keys: an array of keys describing the hierarchical layout of this view in the API;
e.g. ``('snippets', 'list')``, ``('snippets', 'retrieve')``, etc.
:rtype: openapi.Operation
"""
raise NotImplementedError("ViewInspector must implement get_operation()!")
# methods below provided as default implementations for probing inspectors
[docs] def should_filter(self):
"""Determine whether filter backend parameters should be included for this request.
:rtype: bool
"""
if not getattr(self.view, 'filter_backends', None):
return False
if self.method.lower() not in ["get", "delete"]:
return False
return is_list_view(self.path, self.method, self.view)
[docs] def get_filter_parameters(self):
"""Return the parameters added to the view by its filter backends.
:rtype: list[openapi.Parameter]
"""
if not self.should_filter():
return []
fields = []
for filter_backend in self.view.filter_backends:
fields += self.probe_inspectors(self.filter_inspectors, 'get_filter_parameters', filter_backend()) or []
return fields
[docs] def should_page(self):
"""Determine whether paging parameters and structure should be added to this operation's request and response.
:rtype: bool
"""
if not getattr(self.view, 'paginator', None):
return False
if self.method.lower() != 'get':
return False
return is_list_view(self.path, self.method, self.view)
[docs] def serializer_to_schema(self, serializer):
"""Convert a serializer to an OpenAPI :class:`.Schema`.
:param serializers.BaseSerializer serializer: the ``Serializer`` instance
:returns: the converted :class:`.Schema`, or ``None`` in case of an unknown serializer
:rtype: openapi.Schema,openapi.SchemaRef,None
"""
return self.probe_inspectors(
self.field_inspectors, 'get_schema', serializer, {'field_inspectors': self.field_inspectors}
)
[docs] def serializer_to_parameters(self, serializer, in_):
"""Convert a serializer to a possibly empty list of :class:`.Parameter`\ s.
:param serializers.BaseSerializer serializer: the ``Serializer`` instance
:param str in_: the location of the parameters, one of the `openapi.IN_*` constants
:rtype: list[openapi.Parameter]
"""
return self.probe_inspectors(
self.field_inspectors, 'get_request_parameters', serializer, {'field_inspectors': self.field_inspectors},
in_=in_
) or []
[docs] def get_paginated_response(self, response_schema):
"""Add appropriate paging fields to a response :class:`.Schema`.
:param openapi.Schema response_schema: the response schema that must be paged.
:returns: the paginated response class:`.Schema`, or ``None`` in case of an unknown pagination scheme
:rtype: openapi.Schema
"""
return self.probe_inspectors(self.paginator_inspectors, 'get_paginated_response',
self.view.paginator, response_schema=response_schema)