Allow query parameters to be passed to custom changes filters

Author: smithsz

CHANGES.md

@@ -2,6 +2,7 @@
 
 - [NEW] Add custom JSON encoder/decoder option to `Document` constructor.
 - [NEW] Add new view parameters, `stable` and `update`, as keyword arguments to `get_view_result`.
+- [NEW] Allow arbitrary query parameters to be passed to custom changes filters.
 - [FIXED] Case where an exception was raised after successful retry when using `doc.update_field`.
 - [FIXED] Removed unnecessary request when retrieving a Result collection that is less than the 'page_size' value
 

src/cloudant/_common_util.py

@@ -47,6 +47,9 @@
 
 # Argument Types
 
+ANY_ARG = object()
+ANY_TYPE = object()
+
 RESULT_ARG_TYPES = {
     'descending': (bool,),
     'endkey': (int, LONGTYPE, STRTYPE, Sequence,),
@@ -101,6 +104,7 @@
     'filter': (STRTYPE,),
     'include_docs': (bool,),
     'style': (STRTYPE,),
+    ANY_ARG: ANY_TYPE  # pass arbitrary query parameters to a custom filter
 }
 _CHANGES_ARG_TYPES.update(_DB_UPDATES_ARG_TYPES)
 

src/cloudant/feed.py

@@ -1,5 +1,5 @@
 #!/usr/bin/env python
-# Copyright (c) 2015, 2016 IBM. All rights reserved.
+# Copyright (c) 2015, 2018 IBM. All rights reserved.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -21,7 +21,7 @@
 
 from ._2to3 import iteritems_, next_, unicode_, STRTYPE, NONETYPE
 from .error import CloudantArgumentError, CloudantFeedException
-from ._common_util import feed_arg_types, TYPE_CONVERTERS
+from ._common_util import ANY_ARG, ANY_TYPE, feed_arg_types, TYPE_CONVERTERS
 
 class Feed(object):
     """
@@ -111,11 +111,18 @@ def _validate(self, key, val, arg_types):
         Ensures that the key and the value are valid arguments to be used with
         the feed.
         """
-        if key not in arg_types:
-            raise CloudantArgumentError(116, key)
-        if (not isinstance(val, arg_types[key]) or
-                (isinstance(val, bool) and int in arg_types[key])):
-            raise CloudantArgumentError(117, key, arg_types[key])
+        if key in arg_types:
+            arg_type = arg_types[key]
+        else:
+            if ANY_ARG not in arg_types:
+                raise CloudantArgumentError(116, key)
+            arg_type = arg_types[ANY_ARG]
+
+        if arg_type == ANY_TYPE:
+            return
+        if (not isinstance(val, arg_type) or
+                (isinstance(val, bool) and int in arg_type)):
+            raise CloudantArgumentError(117, key, arg_type)
         if isinstance(val, int) and val < 0 and not isinstance(val, bool):
             raise CloudantArgumentError(118, key, val)
         if key == 'feed':

tests/unit/changes_tests.py

@@ -465,14 +465,20 @@ def test_get_feed_using_doc_ids(self):
         self.assertSetEqual(set([x['id'] for x in changes]), expected)
         self.assertTrue(str(feed.last_seq).startswith('100'))
 
-    def test_invalid_argument(self):
+    def test_get_feed_with_custom_filter_query_params(self):
         """
-        Test that an invalid argument is caught and an exception is raised
+        Test using feed with custom filter query parameters.
         """
-        feed = Feed(self.db, foo='bar')
-        with self.assertRaises(CloudantArgumentError) as cm:
-            invalid_feed = [x for x in feed]
-        self.assertEqual(str(cm.exception), 'Invalid argument foo')
+        feed = Feed(
+            self.db,
+            filter='mailbox/new_mail',
+            foo='bar',  # query parameters to a custom filter
+            include_docs=False
+        )
+        params = feed._translate(feed._options)
+        self.assertEquals(params['filter'], 'mailbox/new_mail')
+        self.assertEquals(params['foo'], 'bar')
+        self.assertEquals(params['include_docs'], 'false')
 
     def test_invalid_argument_type(self):
         """