Add condition parameter for getdotattr

sqlalchemy_utils/decorators.py

@@ -3,7 +3,6 @@ import itertools
 import sqlalchemy as sa
 import six
 from .functions import getdotattr
-from .path import AttrPath
 
 
 class AttributeValueGenerator(object):

sqlalchemy_utils/functions/orm.py

@@ -16,6 +16,7 @@ from sqlalchemy.orm.properties import ColumnProperty
 from sqlalchemy.orm.query import _ColumnEntity
 from sqlalchemy.orm.session import object_session
 from sqlalchemy.orm.util import AliasedInsp
+from sqlalchemy_utils.utils import is_sequence
 
 
 def get_column_key(model, column):
@@ -623,7 +624,7 @@ def get_declarative_base(model):
     return model
 
 
-def getdotattr(obj_or_class, dot_path):
+def getdotattr(obj_or_class, dot_path, condition=None):
     """
     Allow dot-notated strings to be passed to `getattr`.
 
@@ -638,22 +639,39 @@ def getdotattr(obj_or_class, dot_path):
     :param dot_path: Attribute path with dot mark as separator
     """
     last = obj_or_class
-    # Coerce object style paths to strings.
-    path = str(dot_path)
 
-    for path in dot_path.split('.'):
+    for path in str(dot_path).split('.'):
         getter = attrgetter(path)
-        if isinstance(last, list):
-            last = sum((getter(el) for el in last), [])
+
+        if is_sequence(last):
+            tmp = []
+            for element in last:
+                value = getter(element)
+                if is_sequence(value):
+                    tmp.extend(value)
+                else:
+                    tmp.append(value)
+            last = tmp
         elif isinstance(last, InstrumentedAttribute):
             last = getter(last.property.mapper.class_)
         elif last is None:
             return None
         else:
             last = getter(last)
+        if condition is not None:
+            if is_sequence(last):
+                last = [v for v in last if condition(v)]
+            else:
+                if not condition(last):
+                    return None
+
     return last
 
 
+def is_deleted(obj):
+    return obj in sa.orm.object_session(obj).deleted
+
+
 def has_changes(obj, attrs=None, exclude=None):
     """
     Simple shortcut function for checking if given attributes of given

sqlalchemy_utils/utils.py

@@ -1,4 +1,7 @@
 import sys
+from collections import Iterable
+
+import six
 
 
 def str_coercible(cls):
@@ -11,3 +14,9 @@ def str_coercible(cls):
 
     cls.__str__ = __str__
     return cls
+
+
+def is_sequence(value):
+    return (
+        isinstance(value, Iterable) and not isinstance(value, six.string_types)
+    )