Merge pull request #122 from mikeywaites/feature/memoize

Feature/memoize

VERSION

@@ -1 +1 @@
-1.0.0-rc5
+1.0.0-rc6

dependencies/dev.txt

@@ -1,2 +1,4 @@
 Sphinx==1.3.1
 sphinx_bootstrap_theme==0.4.5
+ipdb
+arrow

dependencies/test.txt

@@ -3,4 +3,3 @@ pytest-cov==1.8.1
 pytest_spec==0.2.24
 sqlalchemy==1.0.4
 mock==1.3.0
-ipdb

kim/field.py

@@ -197,6 +197,8 @@ def __init__(self, *args, **field_opts):
                 .format(self.__class__.__name__, e.message)
             raise FieldError(msg)
 
+        self._old_value = None
+        self._new_value = None
         set_creation_order(self)
 
     def get_error(self, error_type):
@@ -276,6 +278,29 @@ def serialize(self, mapper_session, **opts):
 
         self.serialize_pipeline(mapper_session, self).run(**opts)
 
+    def set_old_value(self, old_value, new_value):
+        """Store the existing value for this field.  This method assumes the
+        field handles a scalar type.
+        """
+        self._old_value = old_value if old_value != new_value else None
+
+    def set_new_value(self, new_value, old_value):
+        """Store the existing value for this field.  This method assumes the
+        field handles a scalar type.
+        """
+        self._new_value = new_value if new_value != old_value else None
+
+    def get_changes(self):
+        """returns a dict of containing the changes that occurred for this
+        field.
+        """
+
+        return {'old_value': self._old_value, 'new_value': self._new_value}
+
+    def has_changed(self):
+
+        return self._new_value is not None
+
 
 class String(Field):
     """:class:`.String` represents a value that must be valid

kim/mapper.py

@@ -377,6 +377,7 @@ def __init__(self, obj=None, data=None, partial=False, raw=False,
         self.raw = raw
         self.partial = partial
         self.parent = parent
+        self._changes = {}
 
     @property
     def initial_errors(self):
@@ -542,6 +543,18 @@ def get_mapper_session(self, data, output):
 
         return MapperSession(self, data, output, partial=self.partial)
 
+    def set_field_changes(self, field_name, changes):
+        """Store a change object for a field at ``field_name`` inside the
+        mappers changes object.
+        """
+
+        self._changes[field_name] = changes
+
+    def get_changes(self):
+        """return all the field change objects for this mapper
+        """
+        return self._changes
+
     def serialize(self, role='__default__', raw=False):
         """Serialize ``self.obj`` into a dict according to the fields
         defined on this Mapper.
@@ -593,6 +606,9 @@ def marshal(self, role='__default__'):
                 # handle errors from nested mappers.
                 self.errors[field.name] = e.errors
 
+            if field.has_changed():
+                self.set_field_changes(field.name, field.get_changes())
+
         # Call top level mapper validator for validations involving more
         # than one field
         try:

kim/pipelines/base.py

@@ -265,11 +265,25 @@ def update_output_to_source(session):
     """
 
     source = session.field.opts.source
+    old_value = attr_or_key(session.output, source)
+
+    session.field.set_new_value(
+        new_value=session.data, old_value=old_value)
+
     try:
+
         if source == '__self__':
             attr_or_key_update(session.output, session.data)
         else:
-            set_attr_or_key(session.output, session.field.opts.source, session.data)
+            session.field.set_old_value(
+                old_value=old_value, new_value=session.data)
+            set_attr_or_key(session.output,
+                            session.field.opts.source,
+                            session.data)
+
     except (TypeError, AttributeError):
         raise FieldError('output does not support attribute or '
                          'key based set operations')
+
+    session.field.set_new_value(
+        new_value=session.data, old_value=old_value)

kim/pipelines/collection.py

@@ -39,6 +39,28 @@ def marshall_collection(session):
             except IndexError:
                 pass
 
+        """
+        TODO(mike) Kill is_wrapped with Bale Fire.
+
+        Create a new session using the data from the array[i] object.
+        We then call marshal() on the wrapped field passing the new
+        session.  We use the session of the mapper the collection is attached
+        too.  This is weird in the case a collection of Nested fields where
+        you'd expect to use the Nested fields mapper.
+
+        The reason for this is the Field._is_wrapped is used
+        in :func:`get_data_from_name` to specify that the data has
+        already been resolved by the collection.  This allows
+        collection to wrap any field.  Nested will later
+        instantiate its mapper using the data passed from collection.
+
+        This solution is A) extremely confusing and hard to follow B) weird and
+        probably quite brittle.
+
+        ..seealso:
+            :func: `pipelines.base.get_data_from_name`
+            :func: `pipelines.nested.marshal_nested`
+        """
         mapper_session = session.mapper.get_mapper_session(datum, _output)
         wrapped_field.marshal(mapper_session, parent_session=session)
 

kim/utils.py

@@ -35,6 +35,8 @@ def _set_attr_or_key(obj, name, value):
     else:
         setattr(obj, name, value)
 
+    return value
+
 
 def attr_or_key(obj, name):
     """attempt to use getattr to access an attribute of obj, if that fails
@@ -57,7 +59,7 @@ def set_attr_or_key(obj, name, value):
     components = name.split('.')
     for component in components[:-1]:
         obj = _attr_or_key(obj, component)
-    _set_attr_or_key(obj, components[-1], value)
+    return _set_attr_or_key(obj, components[-1], value)
 
 
 def attr_or_key_update(obj, value):

tests/test_pipelines/test_base.py

@@ -1,5 +1,6 @@
 import pytest
 
+from kim.mapper import Mapper, MapperSession
 from kim.field import Field, FieldInvalid, FieldError
 from kim.pipelines.base import (
     Session,
@@ -152,9 +153,14 @@ def test_update_output_to_source_with_object():
     class MyObject(object):
         pass
 
+    class MyMapper(Mapper):
+        pass
+
     output = MyObject()
     field = Field(source='source', required=True)
-    session = Session(field, data, output)
+    mapper_session = MapperSession(
+        MyMapper(data=data), data=data, output=output)
+    session = Session(field, data, output, mapper_session=mapper_session)
     session.data = data['source']
 
     update_output_to_source(session)
@@ -166,12 +172,18 @@ def test_update_output_to_source_with_object_dot_notiation():
     class MyObject(object):
         pass
 
+    class MyMapper(Mapper):
+        pass
+
     output = MyObject()
     output.nested = MyObject()
+    data = {'name': 'mike'}
 
     field = Field(source='nested.source', required=True)
-    session = Session(field, {'name': 'mike'}, output)
-    session.data = 'mike'
+    mapper_session = MapperSession(
+        MyMapper(data=data), data=data, output=output)
+    session = Session(field, data, output, mapper_session=mapper_session)
+    session.data = data['name']
 
     update_output_to_source(session)
     assert output.nested.source == 'mike'
@@ -185,10 +197,15 @@ def test_update_output_to_source_with_dict():
         'nested': {'foo': 'bar'}
     }
 
+    class MyMapper(Mapper):
+        pass
+
     output = {}
 
     field = Field(source='source', required=True)
-    session = Session(field, data, output)
+    mapper_session = MapperSession(
+        MyMapper(data=data), data=data, output=output)
+    session = Session(field, data, output, mapper_session=mapper_session)
     session.data = data['source']
     update_output_to_source(session)
     assert output == {'source': 'mike'}
@@ -202,8 +219,13 @@ def test_update_output_to_source_invalid_output_type():
         'nested': {'foo': 'bar'}
     }
 
+    class MyMapper(Mapper):
+        pass
+
     output = 1
     field = Field(source='source', required=True)
-    session = Session(field, data, output)
+    mapper_session = MapperSession(
+        MyMapper(data=data), data=data, output=output)
+    session = Session(field, data, output, mapper_session=mapper_session)
     with pytest.raises(FieldError):
         update_output_to_source(session)

tests/test_pipelines/test_boolean.py

@@ -92,6 +92,56 @@ def test_boolean_input():
     assert output == {'is_active': True}
 
 
+def test_boolean_memoize_no_existing_value():
+    """ensure field sets only the new_value when the field has no
+    exsiting value.
+    """
+
+    field = Boolean(name='is_active', required=True)
+
+    output = {}
+    mapper_session = get_mapper_session(
+        data={'is_active': True, 'email': 'mike@mike.com'},
+        output=output)
+
+    field.marshal(mapper_session)
+    assert field._old_value is None
+    assert field._new_value is True
+
+
+def test_boolean_memoize_no_change():
+    """ensure field sets no changes when the field value remains the same
+    """
+
+    field = Boolean(name='is_active', required=True)
+
+    output = {'is_active': False}
+    mapper_session = get_mapper_session(
+        data={'is_active': False, 'email': 'mike@mike.com'},
+        output=output)
+
+    field.marshal(mapper_session)
+    assert field._old_value is None
+    assert field._new_value is None
+
+
+def test_boolean_memoize_new_value():
+    """ensure field sets both old value and new value when the field has an
+    existing value and a new value is provided.
+    """
+
+    field = Boolean(name='is_active', required=True)
+
+    output = {'is_active': False}
+    mapper_session = get_mapper_session(
+        data={'is_active': True, 'email': 'mike@mike.com'},
+        output=output)
+
+    field.marshal(mapper_session)
+    assert field._old_value is False
+    assert field._new_value is True
+
+
 def test_boolean_input_with_allow_none():
 
     field = Boolean(name='is_active', required=False, allow_none=True)