Support action API requests

In some cases, the application needs to expose APIs that do not map to
the standard HTTP methods.  We support these requests using POST with
a mandatory 'action' query parameter that maps to the associated call in
the associated resource model.

Change-Id: I43bfaa954a85fa434beb1c5cf7b1ae18036f9ede

congress/api/webservice.py

@@ -138,8 +138,8 @@ class ElementHandler(AbstractApiHandler):
     """
 
     def __init__(self, path_regex, model,
-                 collection_handler=None, allow_read=True, allow_replace=True,
-                 allow_update=True, allow_delete=True):
+                 collection_handler=None, allow_read=True, allow_actions=True,
+                 allow_replace=True, allow_update=True, allow_delete=True):
         """Initialize an element handler.
 
         Args:
@@ -160,6 +160,7 @@ class ElementHandler(AbstractApiHandler):
         self.model = model
         self.collection_handler = collection_handler
         self.allow_read = allow_read
+        self.allow_actions = allow_actions
         self.allow_replace = allow_replace
         self.allow_update = allow_update
         self.allow_delete = allow_delete
@@ -181,7 +182,8 @@ class ElementHandler(AbstractApiHandler):
         """
         if request.method == 'GET' and self.allow_read:
             return self.read(request)
-        #TODO(pballand): POST for controller semantics
+        elif request.method == 'POST' and self.allow_actions:
+            return self.action(request)
         elif request.method == 'PUT' and self.allow_replace:
             return self.replace(request)
         elif request.method == 'PATCH' and self.allow_update:
@@ -203,6 +205,30 @@ class ElementHandler(AbstractApiHandler):
                               status=httplib.OK,
                               content_type='application/json')
 
+    def action(self, request):
+        # Non-CRUD operations must specify an 'action' parameter
+        action = request.params.getall('action')
+        if len(action) != 1:
+            if len(action) > 1:
+                errstr = "Action parameter may not be provided multiple times."
+            else:
+                errstr = "Missing required action parameter."
+            return error_response(httplib.BAD_REQUEST, 400, errstr)
+        model_method = "%s_action" % action[0]
+        f = getattr(self.model, model_method, None)
+        if f is None:
+            return NOT_SUPPORTED_RESPONSE
+        try:
+            response = f(request.params, context=self._get_context(request),
+                         request=request)
+            if isinstance(response, webob.Response):
+                return response
+            return webob.Response(body="%s\n" % json.dumps(response),
+                                  status=httplib.OK,
+                                  content_type='application/json')
+        except TypeError:
+            return NOT_SUPPORTED_RESPONSE
+
     def replace(self, request):
         if not hasattr(self.model, 'update_item'):
             return NOT_SUPPORTED_RESPONSE

congress/tests/api/test_webservice.py

@@ -16,6 +16,7 @@ import httplib
 import json
 import unittest
 import uuid
+import webob
 
 from congress.api import webservice
 from congress.tests import base
@@ -145,6 +146,64 @@ class TestSimpleDataModel(unittest.TestCase):
                 model.delete_item(self.UNADDED_ID, {}, context=context),
 
 
+class TestElementHandler(base.TestCase):
+
+    def test_read(self):
+        # TODO(pballand): write tests
+        pass
+
+    def test_action(self):
+        element_handler = webservice.ElementHandler(r'/', '')
+        element_handler.model = webservice.SimpleDataModel("test")
+        request = MagicMock()
+        request.path = "/"
+
+        response = element_handler.action(request)
+        self.assertEqual(400, response.status_code)
+        self.assertEqual('application/json', response.content_type)
+        self.assertEqual(json.loads(response.body)['description'],
+                         "Missing required action parameter.")
+
+        request.params = MagicMock()
+        request.params.getall.return_value = ['do_test']
+        request.params["action"] = "do_test"
+        request.path = "/"
+        response = element_handler.action(request)
+        self.assertEqual(501, response.status_code)
+        self.assertEqual('application/json', response.content_type)
+        self.assertEqual(json.loads(response.body)['description'],
+                         "Method not supported")
+
+        # test action impl returning python primitives
+        simple_data = [1, 2]
+        element_handler.model.do_test_action = lambda *a, **kwa: simple_data
+        response = element_handler.action(request)
+        self.assertEqual(200, response.status_code)
+        self.assertEqual('application/json', response.content_type)
+        self.assertEqual(json.loads(response.body), simple_data)
+
+        # test action impl returning custom webob response
+        custom_data = webob.Response(body="test", status=599,
+                                     content_type="custom/test")
+        element_handler.model.do_test_action = lambda *a, **kwa: custom_data
+        response = element_handler.action(request)
+        self.assertEqual(599, response.status_code)
+        self.assertEqual('custom/test', response.content_type)
+        self.assertEqual(response.body, "test")
+
+    def test_replace(self):
+        # TODO(pballand): write tests
+        pass
+
+    def test_update(self):
+        # TODO(pballand): write tests
+        pass
+
+    def test_delete(self):
+        # TODO(pballand): write tests
+        pass
+
+
 class TestCollectionHandler(base.TestCase):
 
     def test_get_action_type(self):