handle SA ORM attributes and hybrid properties for relationship form …

…fields

refs #174

keg_elements/forms/__init__.py

@@ -331,10 +331,18 @@ def __init__(self, label=None, orm_cls=None, label_attr=None, fk_attr='id',
                  query_filter=None, coerce=_not_given, **kwargs):
         label = self.field_label_modifier(label)
         self.orm_cls = orm_cls
+
         self.label_attr = label_attr
         if self.label_attr is None:
             self.label_attr = self.get_best_label_attr()
+        if self.label_attr:
+            # compute this once and store on the object, rather than for each option
+            self.label_attr_name = self.compute_option_attr_name(self.label_attr)
+
         self.fk_attr = fk_attr
+        if self.fk_attr:
+            self.fk_attr_name = self.compute_option_attr_name(self.fk_attr)
+
         self.query_filter = query_filter
         if not self.fk_attr and not coerce:
             def coerce_to_orm_obj(value):
@@ -350,6 +358,19 @@ def coerce_to_orm_obj(value):
 
         super().__init__(label=label, choices=self.get_choices, coerce=coerce, **kwargs)
 
+    def compute_option_attr_name(self, base_attr):
+        """To access the label value on an option in the result set, we need to know what
+        attribute to use. Based on ``label_attr``, which can be string, SA ORM attr,
+        SA hybrid attr, etc., determine a sane attribute."""
+        retval = base_attr
+
+        if isinstance(base_attr, sa.orm.InstrumentedAttribute):
+            retval = base_attr.name
+        else:
+            retval = getattr(base_attr, '__name__', str(base_attr))
+
+        return retval
+
     def field_label_modifier(self, label):
         """Modifies the label to something more human-friendly.
 
@@ -366,11 +387,14 @@ def build_query(self):
         return query
 
     def query_base(self):
-        return self.orm_cls.query.order_by(self.label_attr)
+        orm_label_attr = self.label_attr
+        if isinstance(self.label_attr, str):
+            orm_label_attr = getattr(self.orm_cls, self.label_attr)
+        return self.orm_cls.query.order_by(orm_label_attr)
 
     def get_data_filter(self):
         if self.fk_attr:
-            return getattr(self.orm_cls, self.fk_attr) == self.data
+            return getattr(self.orm_cls, self.fk_attr_name) == self.data
         else:
             return self.orm_cls.id == self.data.id
 
@@ -407,7 +431,7 @@ def get_best_label_attr(self):
 
     def get_option_label(self, obj):
         if self.label_attr:
-            return getattr(obj, self.label_attr)
+            return getattr(obj, self.label_attr_name)
 
         return str(obj)
 
@@ -416,7 +440,7 @@ def get_choices(self):
 
         def get_value(obj):
             if self.fk_attr:
-                return str(getattr(obj, self.fk_attr))
+                return str(getattr(obj, self.fk_attr_name))
 
             return str(obj.id)
 
@@ -437,9 +461,6 @@ class RelationshipField(RelationshipFieldBase, SelectField):
         orm_cls (class): Model class of the relationship attribute. Used to query
         records for populating select options.
 
-        relationship_attr (str): Name of the attribute on form model that refers to
-        the relationship object. Typically this is a foreign key ID.
-
         label_attr (str): Name of attribute on relationship class to use for select
         option labels.
 
@@ -478,9 +499,6 @@ class RelationshipMultipleField(RelationshipFieldBase, SelectMultipleField):
         orm_cls (class): Model class of the relationship attribute. Used to query
         records for populating select options.
 
-        relationship_attr (str): Name of the collection on form model that refers to
-        the relationship object.
-
         label_attr (str): Name of attribute on relationship class to use for select
         option labels.
 

keg_elements/tests/test_forms/test_form.py

@@ -944,7 +944,6 @@ def test_options_include_form_obj_value(self):
         )
 
         self.assert_object_options(self.get_field(form), [foo_thing, thing1])
-        assert self.get_field(form).data == self.coerce(foo_thing.id)
 
     def test_options_sorted(self):
         thing_b = ents.Thing.testing_create(name='BBB')
@@ -1017,6 +1016,56 @@ def test_coerce_formdata(self):
         assert form.thing.data == thing
 
 
+class TestOrmRelationshipOrmAttr(TestOrmRelationship):
+    """Test a relationship field that uses an ORM attr for the label."""
+
+    def create_relationship(self, query_filter=None):
+        return RelationshipField('Thing', ents.Thing, ents.Thing.name, query_filter=query_filter,
+                                 fk_attr=None)
+
+
+class TestOrmRelationshipOrmFkAttr(TestOrmRelationship):
+    """Test a relationship field that uses an ORM attr for the fk."""
+
+    def create_relationship(self, query_filter=None):
+        return RelationshipField('Thing', ents.Thing, 'name', query_filter=query_filter,
+                                 fk_attr=ents.Thing.id)
+
+    def create_form(self, relationship, **kwargs):
+        class RelatedThingForm(ModelForm):
+            thing_id = relationship
+
+            class Meta:
+                model = ents.RelatedThing
+
+        return RelatedThingForm(**kwargs)
+
+    def get_field(self, form):
+        return form.thing_id
+
+    def test_coerce_formdata(self):
+        thing = ents.Thing.testing_create()
+        form = self.create_form(self.create_relationship(),
+                                formdata=MultiDict({'thing_id': str(thing.id)}))
+        assert form.thing_id.data == thing.id
+
+
+class TestOrmRelationshipOrmHybridAttr(TestOrmRelationshipOrmAttr):
+    """Test a relationship field that uses an ORM hybrid property attr for the label."""
+
+    def create_relationship(self, query_filter=None):
+        return RelationshipField('Thing', ents.Thing, ents.Thing.hybrid_name,
+                                 query_filter=query_filter, fk_attr=None)
+
+
+class TestOrmRelationshipOrmHybridFkAttr(TestOrmRelationshipOrmFkAttr):
+    """Test a relationship field that uses an ORM hybrid property for the fk."""
+
+    def create_relationship(self, query_filter=None):
+        return RelationshipField('Thing', ents.Thing, 'name', query_filter=query_filter,
+                                 fk_attr=ents.Thing.hybrid_id)
+
+
 class TestRelationshipFieldGenerator:
     def setup_method(self):
         ents.Thing.delete_cascaded()

kegel_app/model/entities.py

@@ -56,6 +56,22 @@ def name_and_color(self):
     def name_and_color(cls):
         return cls.name + sa.sql.literal('-') + cls.color
 
+    @sa.ext.hybrid.hybrid_property
+    def hybrid_name(self):
+        return self.name
+
+    @hybrid_name.expression
+    def hybrid_name(cls):
+        return cls.name
+
+    @sa.ext.hybrid.hybrid_property
+    def hybrid_id(self):
+        return self.id
+
+    @hybrid_id.expression
+    def hybrid_id(cls):
+        return cls.id
+
     @classmethod
     def random_color(cls):
         return 'blue'