Bug fix in DynamicDocument which isn not parsing known fields in constructor like Document do #2412

docs/changelog.rst

@@ -6,6 +6,7 @@ Changelog
 Development
 ===========
 - (Fill this out as you fix issues and develop your features).
+- Bug fix in DynamicDocument which isn not parsing known fields in constructor like Document do #2412
 - When using pymongo >= 3.7, make use of Collection.count_documents instead of Collection.count
     and Cursor.count that got deprecated in pymongo >= 3.7.
     This should have a negative impact on performance of count see Issue #2219

mongoengine/base/document.py

@@ -117,25 +117,22 @@ class BaseDocument:
         if "_cls" not in values:
             self._cls = self._class_name
 
-        # Set passed values after initialisation
+        # Set actual values
-        if self._dynamic:
         dynamic_data = {}
-            for key, value in values.items():
-                if key in self._fields or key == "_id":
-                    setattr(self, key, value)
-                else:
-                    dynamic_data[key] = value
-        else:
         FileField = _import_class("FileField")
         for key, value in values.items():
             key = self._reverse_db_field_map.get(key, key)
-                if key in self._fields or key in ("id", "pk", "_cls"):
-                    if __auto_convert and value is not None:
             field = self._fields.get(key)
+            if field or key in ("id", "pk", "_cls"):
+                if __auto_convert and value is not None:
                     if field and not isinstance(field, FileField):
                         value = field.to_python(value)
                 setattr(self, key, value)
             else:
+                if self._dynamic:
+                    dynamic_data[key] = value
+                else:
+                    # For strict Document
                     self._data[key] = value
 
         # Set any get_<field>_display methods

tests/document/test_dynamic.py

@@ -37,6 +37,19 @@ class TestDynamicDocument(MongoDBTestCase):
         # Confirm no changes to self.Person
         assert not hasattr(self.Person, "age")
 
+    def test_dynamic_document_parse_values_in_constructor_like_document_do(self):
+        class ProductDynamicDocument(DynamicDocument):
+            title = StringField()
+            price = FloatField()
+
+        class ProductDocument(Document):
+            title = StringField()
+            price = FloatField()
+
+        product = ProductDocument(title="Blabla", price="12.5")
+        dyn_product = ProductDynamicDocument(title="Blabla", price="12.5")
+        assert product.price == dyn_product.price == 12.5
+
     def test_change_scope_of_variable(self):
         """Test changing the scope of a dynamic field has no adverse effects"""
         p = self.Person()