From 6c0112c2be3da38e50471ffa764a64f2008ab541 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Wilson=20J=C3=BAnior?= <wilsonpjunior@gmail.com>
Date: Fri, 25 Jul 2014 18:12:26 -0300
Subject: [PATCH] refs #709, added support to disable auto_sync

---
 mongoengine/base/metaclasses.py |  9 +++--
 mongoengine/fields.py           | 29 ++++++++++++--
 tests/fields/fields.py          | 70 +++++++++++++++++++++++++++++++++
 3 files changed, 101 insertions(+), 7 deletions(-)

diff --git a/mongoengine/base/metaclasses.py b/mongoengine/base/metaclasses.py
index b7157a35..a4bd0144 100644
--- a/mongoengine/base/metaclasses.py
+++ b/mongoengine/base/metaclasses.py
@@ -31,7 +31,7 @@ class DocumentMetaclass(type):
 
         attrs['_is_document'] = attrs.get('_is_document', False)
         attrs['_cached_reference_fields'] = []
-        
+
         # EmbeddedDocuments could have meta data for inheritance
         if 'meta' in attrs:
             attrs['_meta'] = attrs.pop('meta')
@@ -181,9 +181,12 @@ class DocumentMetaclass(type):
                 if not f.document_type:
                     raise InvalidDocumentError(
                         "Document is not avaiable to sync")
-                
+
+                if f.auto_sync:
+                    f.start_listener()
+
                 f.document_type._cached_reference_fields.append(f)
-                
+
             if isinstance(f, ComplexBaseField) and hasattr(f, 'field'):
                 delete_rule = getattr(f.field,
                                       'reverse_delete_rule',
diff --git a/mongoengine/fields.py b/mongoengine/fields.py
index 9b19f25d..14fcde68 100644
--- a/mongoengine/fields.py
+++ b/mongoengine/fields.py
@@ -989,10 +989,11 @@ class CachedReferenceField(BaseField):
     .. versionadded:: 0.9
     """
 
-    def __init__(self, document_type, fields=[], **kwargs):
+    def __init__(self, document_type, fields=[], auto_sync=True, **kwargs):
         """Initialises the Cached Reference Field.
 
         :param fields:  A list of fields to be cached in document
+        :param auto_sync: if True documents are auto updated.
         """
         if not isinstance(document_type, basestring) and \
                 not issubclass(document_type, (Document, basestring)):
@@ -1000,10 +1001,33 @@ class CachedReferenceField(BaseField):
             self.error('Argument to CachedReferenceField constructor must be a'
                        ' document class or a string')
 
+        self.auto_sync = auto_sync
         self.document_type_obj = document_type
         self.fields = fields
         super(CachedReferenceField, self).__init__(**kwargs)
 
+    def start_listener(self):
+        """
+        Start listener for document alterations, and update relacted docs
+        """
+        from mongoengine import signals
+        signals.post_save.connect(self.on_document_pre_save,
+                                  sender=self.document_type)
+
+    def on_document_pre_save(self, sender, document, created, **kwargs):
+        if not created:
+            update_kwargs = {
+                'set__%s__%s' % (self.name, k): v
+                for k, v in document._delta()[0].items()
+                if k in self.fields}
+
+            if update_kwargs:
+                filter_kwargs = {}
+                filter_kwargs[self.name] = document
+
+                self.owner_document.objects(
+                    **filter_kwargs).update(**update_kwargs)
+
     def to_python(self, value):
         """Convert a MongoDB-compatible type to a Python type.
         """
@@ -1088,7 +1112,6 @@ class CachedReferenceField(BaseField):
 
     def sync_all(self):
         update_key = 'set__%s' % self.name
-        errors = []
 
         for doc in self.document_type.objects:
             filter_kwargs = {}
@@ -1097,8 +1120,6 @@ class CachedReferenceField(BaseField):
             update_kwargs = {}
             update_kwargs[update_key] = doc
 
-            errors.append((filter_kwargs, update_kwargs))
-
             self.owner_document.objects(
                 **filter_kwargs).update(**update_kwargs)
 
diff --git a/tests/fields/fields.py b/tests/fields/fields.py
index d5ae3329..77490ddb 100644
--- a/tests/fields/fields.py
+++ b/tests/fields/fields.py
@@ -1608,6 +1608,76 @@ class FieldTest(unittest.TestCase):
 
         self.assertRaises(InvalidDocumentError, build)
 
+    def test_cached_reference_auto_sync(self):
+        class Person(Document):
+            TYPES = (
+                ('pf', "PF"),
+                ('pj', "PJ")
+            )
+            name = StringField()
+            tp = StringField(
+                choices=TYPES
+            )
+
+            father = CachedReferenceField('self', fields=('tp',))
+
+        Person.drop_collection()
+
+        a1 = Person(name="Wilson Father", tp="pj")
+        a1.save()
+
+        a2 = Person(name='Wilson Junior', tp='pf', father=a1)
+        a2.save()
+
+        a1.tp = 'pf'
+        a1.save()
+
+        a2.reload()
+        self.assertEqual(dict(a2.to_mongo()), {
+            '_id': a2.pk,
+            'name': 'Wilson Junior',
+            'tp': 'pf',
+            'father': {
+                '_id': a1.pk,
+                'tp': 'pf'
+            }
+        })
+
+    def test_cached_reference_auto_sync_disabled(self):
+        class Persone(Document):
+            TYPES = (
+                ('pf', "PF"),
+                ('pj', "PJ")
+            )
+            name = StringField()
+            tp = StringField(
+                choices=TYPES
+            )
+
+            father = CachedReferenceField(
+                'self', fields=('tp',), auto_sync=False)
+
+        Persone.drop_collection()
+
+        a1 = Persone(name="Wilson Father", tp="pj")
+        a1.save()
+
+        a2 = Persone(name='Wilson Junior', tp='pf', father=a1)
+        a2.save()
+
+        a1.tp = 'pf'
+        a1.save()
+
+        self.assertEqual(Persone.objects._collection.find_one({'_id': a2.pk}), {
+            '_id': a2.pk,
+            'name': 'Wilson Junior',
+            'tp': 'pf',
+            'father': {
+                '_id': a1.pk,
+                'tp': 'pj'
+            }
+        })
+
     def test_cached_reference_embedded_fields(self):
         class Owner(EmbeddedDocument):
             TPS = (