add request/response hooks to adapter utility

CHANGES.rst

@@ -4,6 +4,11 @@ Changes
 Unreleased
 ==========
 
+Changes:
+
+* Add request and response hooks operations to adapter allowing derived implementations to modify OWS proxied requests
+  and returned responses from the service. The default adapter applies no modifications to the original definitions.
+
 0.6.2 (2021-12-01)
 ==================
 

requirements.txt

@@ -32,3 +32,5 @@ pyramid_oauthlib>=0.4.1
 oauthlib<3
 requests_oauthlib<1.2.0
 PyJWT>=2
+# typing extension required for TypedDict
+typing_extensions; python_version < "3.8"

twitcher/adapter/base.py

@@ -2,10 +2,13 @@
 
 from typing import TYPE_CHECKING
 if TYPE_CHECKING:
-    from twitcher.typedefs import AnySettingsContainer, JSON
-    from twitcher.interface import OWSSecurityInterface, OWSRegistryInterface
     from pyramid.config import Configurator
     from pyramid.request import Request
+    from pyramid.response import Response
+
+    from twitcher.interface import OWSSecurityInterface, OWSRegistryInterface
+    from twitcher.models.service import ServiceConfig
+    from twitcher.typedefs import AnySettingsContainer, JSON
 
 
 class AdapterInterface(object):
@@ -54,3 +57,31 @@ def owsproxy_config(self, container):
         Returns the 'owsproxy' implementation of the adapter.
         """
         raise NotImplementedError
+
+    def request_hook(self, request, service):
+        # type: (Request, ServiceConfig) -> Request
+        """
+        Apply modifications onto the request before sending it.
+
+        .. versionadded:: 0.7.0
+
+        Request members employed after this hook is called include:
+        - :meth:`Request.headers`
+        - :meth:`Request.method`
+        - :meth:`Request.body`
+
+        This method can modified those members to adapt the request for specific service logic.
+        """
+        raise NotImplementedError
+
+    def response_hook(self, response, service):
+        # type: (Response, ServiceConfig) -> Response
+        """
+        Apply modifications onto the response from sent request.
+
+        .. versionadded:: 0.7.0
+
+        The received response from the proxied service is normally returned directly.
+        This method can modify the response to adapt it for specific service logic.
+        """
+        raise NotImplementedError

twitcher/adapter/default.py

@@ -37,3 +37,9 @@ def owsproxy_config(self, container):
         if not isinstance(container, Configurator):
             container = self.configurator_factory(container)
         owsproxy_defaultconfig(container)
+
+    def pre_request_hook(self, request, service):
+        return request
+
+    def post_request_hook(self, response, service):
+        return response

twitcher/models/service.py

@@ -4,10 +4,23 @@
     String,
 )
 from sqlalchemy.ext.hybrid import hybrid_property
-from typing import Union
+from typing import TYPE_CHECKING, Union
 
 from .meta import Base
 
+if TYPE_CHECKING:
+    from twitcher.typedefs import TypedDict
+
+    ServiceConfig = TypedDict("ServiceConfig", {
+        "url": str,
+        "name": str,
+        "type": str,
+        "purl": str,
+        "auth": str,
+        "public": bool,
+        "verify": bool
+    }, total=True)
+
 
 class Service(Base):
     __tablename__ = 'services'
@@ -21,20 +34,22 @@ class Service(Base):
 
     @hybrid_property
     def verify(self):
+        # type: () -> bool
         if self._verify == 1:
             return True
         return False
 
     @verify.setter
-    def verify(self, verify: Union[bool, int]):
+    def verify(self, verify: Union[bool, int]) -> None:
         self._verify = int(verify)
 
     @property
-    def public(self):
+    def public(self) -> bool:
         """Return true if public access."""
         return self.auth not in ['token', 'cert']
 
     def json(self):
+        # type: () -> ServiceConfig
         return {
             'url': self.url,
             'name': self.name,

twitcher/owsproxy.py

@@ -12,19 +12,20 @@
 from typing import TYPE_CHECKING
 
 from twitcher.owsexceptions import OWSAccessForbidden, OWSAccessFailed, OWSException, OWSNoApplicableCode
-from twitcher.utils import (
-    replace_caps_url,
-    get_settings,
-    get_twitcher_url,
-    is_valid_url)
+from twitcher.utils import get_settings, get_twitcher_url, is_valid_url, replace_caps_url
 
 import logging
 LOGGER = logging.getLogger('TWITCHER')
 
 if TYPE_CHECKING:
-    from twitcher.typedefs import AnySettingsContainer  # noqa: F401
-    from pyramid.config import Configurator             # noqa: F401
-    from typing import AnyStr                           # noqa: F401
+    from typing import Optional
+
+    from pyramid.config import Configurator
+    from pyramid.request import Request
+
+    from twitcher.adapter.base import AdapterInterface
+    from twitcher.models.service import ServiceConfig
+    from twitcher.typedefs import AnySettingsContainer
 
 
 allowed_content_types = (
@@ -64,6 +65,7 @@ def __iter__(self):
 
 
 def _send_request(request, service, extra_path=None, request_params=None):
+    # type: (Request, ServiceConfig, Optional[str], Optional[str]) -> Response
 
     # TODO: fix way to build url
     url = service['url']
@@ -141,19 +143,20 @@ def _send_request(request, service, extra_path=None, request_params=None):
 
 
 def owsproxy_base_path(container):
-    # type: (AnySettingsContainer) -> AnyStr
+    # type: (AnySettingsContainer) -> str
     settings = get_settings(container)
     return settings.get('twitcher.ows_proxy_protected_path', '/ows').rstrip('/').strip()
 
 
 def owsproxy_base_url(container):
-    # type: (AnySettingsContainer) -> AnyStr
+    # type: (AnySettingsContainer) -> str
     twitcher_url = get_twitcher_url(container)
     owsproxy_path = owsproxy_base_path(container)
     return twitcher_url + owsproxy_path
 
 
 def owsproxy_view(request):
+    # type: (Request) -> Response
     service_name = request.matchdict.get('service_name')
     try:
         extra_path = request.matchdict.get('extra_path')
@@ -167,7 +170,10 @@ def owsproxy_view(request):
     try:
         if not request.is_verified:
             raise OWSAccessForbidden("Access to service is forbidden.")
-        return _send_request(request, service, extra_path, request_params=request.query_string)
+        request = request.adapter.request_hook(request, service)
+        response = _send_request(request, service, extra_path, request_params=request.query_string)
+        response = request.adapter.response_hook(response, service)
+        return response
     except OWSException as exc:
         LOGGER.warning("Security check failed but was not handled as expected by 'is_verified' method.", exc_info=exc)
         raise
@@ -192,5 +198,13 @@ def owsproxy_defaultconfig(config):
 
 
 def includeme(config):
+    # type: (Configurator) -> None
     from twitcher.adapter import get_adapter_factory
+
+    def get_adapter(request):
+        # type: (Request) -> AdapterInterface
+        adapter = get_adapter_factory(request)
+        return adapter
+
     get_adapter_factory(config).owsproxy_config(config)
+    config.add_request_method(get_adapter, reify=False, property=True, name="adapter")

twitcher/typedefs.py

@@ -1,3 +1,4 @@
+import typing
 from typing import TYPE_CHECKING
 if TYPE_CHECKING:
     from typing import AnyStr, Dict, List, Tuple, Union
@@ -10,6 +11,11 @@
     from webob.headers import ResponseHeaders, EnvironHeaders
     from webtest.response import TestResponse
 
+    if hasattr(typing, "TypedDict"):
+        from typing import TypedDict  # pylint: disable=E0611,no-name-in-module
+    else:
+        from typing_extensions import TypedDict  # noqa
+
     Number = Union[int, float]
     AnyValue = Union[AnyStr, Number, bool, None]
     AnyKey = Union[AnyStr, int]