Introducing feature variable accessors (#86)

Author: aliabbasrizvi

optimizely/optimizely.py

@@ -15,13 +15,13 @@
 import sys
 
 from . import decision_service
+from . import entities
 from . import event_builder
 from . import exceptions
 from . import project_config
 from .error_handler import NoOpErrorHandler as noop_error_handler
 from .event_dispatcher import EventDispatcher as default_event_dispatcher
 from .helpers import enums
-from .helpers import event_tag_utils
 from .helpers import validator
 from .logger import NoOpLogger as noop_logger
 from .logger import SimpleLogger
@@ -178,6 +178,64 @@ def _send_impression_event(self, experiment, variation, user_id, attributes):
       error = sys.exc_info()[1]
       self.logger.log(enums.LogLevels.ERROR, 'Unable to dispatch impression event. Error: %s' % str(error))
 
+  def _get_feature_variable_for_type(self, feature_key, variable_key, variable_type, user_id, attributes):
+    """ Helper method to determine value for a certain variable attached to a feature flag based on type of variable.
+
+    Args:
+      feature_key: Key of the feature whose variable's value is being accessed.
+      variable_key: Key of the variable whose value is to be accessed.
+      variable_type: Type of variable which could be one of boolean/double/integer/string.
+      user_id: ID for user.
+      attributes: Dict representing user attributes.
+
+    Returns:
+      Value of the variable. None if:
+      - Feature key is invalid.
+      - Variable key is invalid.
+      - Mismatch with type of variable.
+    """
+
+    feature_flag = self.config.get_feature_from_key(feature_key)
+    if not feature_flag:
+      return None
+
+    variable = self.config.get_variable_for_feature(feature_key, variable_key)
+    if not variable:
+      return None
+
+    # Return None if type differs
+    if variable.type != variable_type:
+      self.logger.log(
+        enums.LogLevels.WARNING,
+        'Requested variable type "%s", but variable is of type "%s". '
+        'Use correct API to retrieve value. Returning None.' % (variable_type, variable.type)
+      )
+      return None
+
+    decision = self.decision_service.get_variation_for_feature(feature_flag, user_id, attributes)
+    if decision.variation:
+      variable_value = self.config.get_variable_value_for_variation(variable, decision.variation)
+      self.logger.log(
+        enums.LogLevels.INFO,
+        'Value for variable "%s" of feature flag "%s" is %s for user "%s".' % (
+          variable_key, feature_key, variable_value, user_id
+        ))
+    else:
+      variable_value = variable.defaultValue
+      self.logger.log(
+        enums.LogLevels.INFO,
+        'User "%s" is not in any variation or rollout rule. '
+        'Returning default value for variable "%s" of feature flag "%s".' % (user_id, variable_key, feature_key)
+      )
+
+    try:
+      actual_value = self.config.get_typecast_value(variable_value, variable_type)
+    except:
+      self.logger.log(enums.LogLevels.ERROR, 'Unable to cast value. Returning None.')
+      actual_value = None
+
+    return actual_value
+
   def activate(self, experiment_key, user_id, attributes=None):
     """ Buckets visitor and sends impression event to Optimizely.
 
@@ -350,6 +408,82 @@ def get_enabled_features(self, user_id, attributes=None):
 
     return enabled_features
 
+  def get_feature_variable_boolean(self, feature_key, variable_key, user_id, attributes=None):
+    """ Returns value for a certain boolean variable attached to a feature flag.
+
+    Args:
+      feature_key: Key of the feature whose variable's value is being accessed.
+      variable_key: Key of the variable whose value is to be accessed.
+      user_id: ID for user.
+      attributes: Dict representing user attributes.
+
+    Returns:
+      Boolean value of the variable. None if:
+      - Feature key is invalid.
+      - Variable key is invalid.
+      - Mismatch with type of variable.
+    """
+
+    variable_type = entities.Variable.Type.BOOLEAN
+    return self._get_feature_variable_for_type(feature_key, variable_key, variable_type, user_id, attributes)
+
+  def get_feature_variable_double(self, feature_key, variable_key, user_id, attributes=None):
+    """ Returns value for a certain double variable attached to a feature flag.
+
+    Args:
+      feature_key: Key of the feature whose variable's value is being accessed.
+      variable_key: Key of the variable whose value is to be accessed.
+      user_id: ID for user.
+      attributes: Dict representing user attributes.
+
+    Returns:
+      Double value of the variable. None if:
+      - Feature key is invalid.
+      - Variable key is invalid.
+      - Mismatch with type of variable.
+    """
+
+    variable_type = entities.Variable.Type.DOUBLE
+    return self._get_feature_variable_for_type(feature_key, variable_key, variable_type, user_id, attributes)
+
+  def get_feature_variable_integer(self, feature_key, variable_key, user_id, attributes=None):
+    """ Returns value for a certain integer variable attached to a feature flag.
+
+    Args:
+      feature_key: Key of the feature whose variable's value is being accessed.
+      variable_key: Key of the variable whose value is to be accessed.
+      user_id: ID for user.
+      attributes: Dict representing user attributes.
+
+    Returns:
+      Integer value of the variable. None if:
+      - Feature key is invalid.
+      - Variable key is invalid.
+      - Mismatch with type of variable.
+    """
+
+    variable_type = entities.Variable.Type.INTEGER
+    return self._get_feature_variable_for_type(feature_key, variable_key, variable_type, user_id, attributes)
+
+  def get_feature_variable_string(self, feature_key, variable_key, user_id, attributes=None):
+    """ Returns value for a certain string variable attached to a feature.
+
+    Args:
+      feature_key: Key of the feature whose variable's value is being accessed.
+      variable_key: Key of the variable whose value is to be accessed.
+      user_id: ID for user.
+      attributes: Dict representing user attributes.
+
+    Returns:
+      String value of the variable. None if:
+      - Feature key is invalid.
+      - Variable key is invalid.
+      - Mismatch with type of variable.
+    """
+
+    variable_type = entities.Variable.Type.STRING
+    return self._get_feature_variable_for_type(feature_key, variable_key, variable_type, user_id, attributes)
+
   def set_forced_variation(self, experiment_key, user_id, variation_key):
     """ Force a user into a variation for a given experiment.
 

optimizely/project_config.py

@@ -153,7 +153,7 @@ def _deserialize_audience(audience_map):
 
     return audience_map
 
-  def _get_typecast_value(self, value, type):
+  def get_typecast_value(self, value, type):
     """ Helper method to determine actual value based on type of feature variable.
 
     Args:
@@ -420,12 +420,13 @@ def get_variable_value_for_variation(self, variable, variation):
     """ Get the variable value for the given variation.
 
     Args:
-      Variable: The Variable for which we are getting the value.
-      Variation: The Variation for which we are getting the variable value.
+      variable: The Variable for which we are getting the value.
+      variation: The Variation for which we are getting the variable value.
 
     Returns:
-      The type-casted variable value or None if any of the inputs are invalid.
+      The variable value or None if any of the inputs are invalid.
     """
+
     if not variable or not variation:
       return None
 
@@ -437,13 +438,13 @@ def get_variable_value_for_variation(self, variable, variation):
     variable_usages = self.variation_variable_usage_map[variation.id]
 
     # Find usage in given variation
-    variable_usage = variable_usages[variable.id]
+    variable_usage = variable_usages.get(variable.id)
 
-    value = self._get_typecast_value(variable_usage.value, variable.type)
-    return value
+    # Return default value in case there is no variable usage for the variable.
+    return variable_usage.value if variable_usage else variable.defaultValue
 
   def get_variable_for_feature(self, feature_key, variable_key):
-    """ Get the variable with the given variable key for the given feature
+    """ Get the variable with the given variable key for the given feature.
 
     Args:
       feature_key: The key of the feature for which we are getting the variable.

tests/base.py

@@ -176,10 +176,23 @@ def setUp(self):
             'id': '127', 'value': 'false'
           }, {
             'id': '128', 'value': 'prod'
+          }, {
+            'id': '129', 'value': '10.01'
+          }, {
+            'id': '130', 'value': '4242'
           }]
         }, {
           'key': 'variation',
-          'id': '111129'
+          'id': '111129',
+          'variables': [{
+            'id': '127', 'value': 'true'
+          }, {
+            'id': '128', 'value': 'staging'
+          }, {
+            'id': '129', 'value': '10.02'
+          }, {
+            'id': '130', 'value': '4243'
+          }]
         }]
       }],
       'groups': [{
@@ -324,6 +337,21 @@ def setUp(self):
             'key': 'environment',
             'defaultValue': 'devel',
             'type': 'string',
+          }, {
+            'id': '129',
+            'key': 'cost',
+            'defaultValue': '10.99',
+            'type': 'double',
+          }, {
+            'id': '130',
+            'key': 'count',
+            'defaultValue': '999',
+            'type': 'integer',
+          }, {
+            'id': '131',
+            'key': 'variable_without_usage',
+            'defaultValue': '45',
+            'type': 'integer',
           }]
       }, {
         'id': '91112',

tests/test_config.py

@@ -1197,14 +1197,14 @@ def test_get_rollout_from_id__valid_rollout_id(self):
     self.assertEqual(expected_rollout, project_config.get_rollout_from_id('211111'))
 
   def test_get_variable_value_for_variation__returns_valid_value(self):
-    """ Test that the right value and type are returned. """
+    """ Test that the right value is returned. """
     opt_obj = optimizely.Optimizely(json.dumps(self.config_dict_with_features))
     project_config = opt_obj.config
 
     variation = project_config.get_variation_from_id('test_experiment', '111128')
     is_working_variable = project_config.get_variable_for_feature('test_feature_in_experiment', 'is_working')
     environment_variable = project_config.get_variable_for_feature('test_feature_in_experiment', 'environment')
-    self.assertEqual(False, project_config.get_variable_value_for_variation(is_working_variable, variation))
+    self.assertEqual('false', project_config.get_variable_value_for_variation(is_working_variable, variation))
     self.assertEqual('prod', project_config.get_variable_value_for_variation(environment_variable, variation))
 
   def test_get_variable_value_for_variation__invalid_variable(self):
@@ -1226,6 +1226,17 @@ def test_get_variable_value_for_variation__no_variables_for_variation(self):
     is_working_variable = project_config.get_variable_for_feature('test_feature_in_experiment', 'is_working')
     self.assertIsNone(project_config.get_variable_value_for_variation(is_working_variable, variation))
 
+  def test_get_variable_value_for_variation__no_usage_of_variable(self):
+    """ Test that a variable with no usage will return default value for variable. """
+
+    opt_obj = optimizely.Optimizely(json.dumps(self.config_dict_with_features))
+    project_config = opt_obj.config
+
+    variation = project_config.get_variation_from_id('test_experiment', '111128')
+    variable_without_usage_variable = project_config.get_variable_for_feature('test_feature_in_experiment',
+                                                                              'variable_without_usage')
+    self.assertEqual('45', project_config.get_variable_value_for_variation(variable_without_usage_variable, variation))
+
   def test_get_variable_for_feature__returns_valid_variable(self):
     """ Test that the feature variable is returned. """