From f9ccf635ca17e7f30efaeccba37b32c7ea062157 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Stefan=20W=C3=B3jcik?= <wojcikstefan@gmail.com>
Date: Sun, 5 Mar 2017 18:20:09 -0500
Subject: [PATCH] Respect db fields in multiple layers of embedded docs (#1501)

---
 mongoengine/base/document.py |  9 ++++++--
 tests/fields/fields.py       | 45 ++++++++++++++++++++++++++++++++++++
 2 files changed, 52 insertions(+), 2 deletions(-)

diff --git a/mongoengine/base/document.py b/mongoengine/base/document.py
index 9d366706..ce96837a 100644
--- a/mongoengine/base/document.py
+++ b/mongoengine/base/document.py
@@ -684,8 +684,13 @@ class BaseDocument(object):
         # class if unavailable
         class_name = son.get('_cls', cls._class_name)
 
-        # Convert SON to a dict, making sure each key is a string
-        data = {str(key): value for key, value in son.iteritems()}
+        # Convert SON to a data dict, making sure each key is a string and
+        # corresponds to the right db field.
+        data = {}
+        for key, value in son.iteritems():
+            key = str(key)
+            key = cls._db_field_map.get(key, key)
+            data[key] = value
 
         # Return correct subclass for document type
         if class_name != cls._class_name:
diff --git a/tests/fields/fields.py b/tests/fields/fields.py
index 8e0da410..2305f3af 100644
--- a/tests/fields/fields.py
+++ b/tests/fields/fields.py
@@ -1901,6 +1901,51 @@ class FieldTest(MongoDBTestCase):
         doc = self.db.test.find_one()
         self.assertEqual(doc['x']['i'], 2)
 
+    def test_double_embedded_db_field(self):
+        """Make sure multiple layers of embedded docs resolve db fields
+        properly and can be initialized using dicts.
+        """
+        class C(EmbeddedDocument):
+            txt = StringField()
+
+        class B(EmbeddedDocument):
+            c = EmbeddedDocumentField(C, db_field='fc')
+
+        class A(Document):
+            b = EmbeddedDocumentField(B, db_field='fb')
+
+        a = A(
+            b=B(
+                c=C(txt='hi')
+            )
+        )
+        a.validate()
+
+        a = A(b={'c': {'txt': 'hi'}})
+        a.validate()
+
+    def test_double_embedded_db_field_from_son(self):
+        """Make sure multiple layers of embedded docs resolve db fields
+        from SON properly.
+        """
+        class C(EmbeddedDocument):
+            txt = StringField()
+
+        class B(EmbeddedDocument):
+            c = EmbeddedDocumentField(C, db_field='fc')
+
+        class A(Document):
+            b = EmbeddedDocumentField(B, db_field='fb')
+
+        a = A._from_son(SON([
+            ('fb', SON([
+                ('fc', SON([
+                    ('txt', 'hi')
+                ]))
+            ]))
+        ]))
+        self.assertEqual(a.b.c.txt, 'hi')
+
     def test_embedded_document_validation(self):
         """Ensure that invalid embedded documents cannot be assigned to
         embedded document fields.