Add support for Computed properties

odata/metadata.py

@@ -38,6 +38,8 @@ class MetaData(object):
         'Edm.Guid': UUIDProperty,
     }
 
+    _annotation_term_computed = 'Org.OData.Core.V1.Computed'
+
     def __init__(self, service):
         self.url = service.url + '$metadata/'
         self.connection = service.default_context.connection
@@ -135,11 +137,13 @@ def _create_entities(self, all_types, entities, entity_sets, entity_base_class,
 
                     if property_type and issubclass(property_type, EnumType):
                         property_instance = EnumTypeProperty(prop_name, enum_class=property_type)
+                        property_instance.is_computed_value = prop['is_computed_value']
                     else:
                         type_ = self.property_type_to_python(prop['type'])
                         type_options = {
                             'primary_key': prop['is_primary_key'],
                             'is_collection': prop['is_collection'],
+                            'is_computed_value': prop['is_computed_value'],
                         }
                         property_instance = type_(prop_name, **type_options)
                     setattr(entity_class, prop_name, property_instance)
@@ -356,11 +360,20 @@ def _parse_entity(self, xmlq, entity_element, schema_name, schema_alias):
             p_type = entity_property.attrib['Type']
 
             is_collection, p_type = self._type_is_collection(p_type)
+            is_computed_value = False
+
+            for annotation in xmlq(entity_property, 'edm:Annotation'):
+                annotation_term = annotation.attrib.get('Term', '')
+                annotation_bool = annotation.attrib.get('Bool') == 'true'
+                if annotation_term == self._annotation_term_computed:
+                    is_computed_value = annotation_bool
+
             entity['properties'].append({
                 'name': p_name,
                 'type': p_type,
                 'is_primary_key': p_name in entity_pks,
                 'is_collection': is_collection,
+                'is_computed_value': is_computed_value,
             })
 
         for nav_property in xmlq(entity_element, 'edm:NavigationProperty'):

odata/property.py

@@ -66,14 +66,15 @@ class PropertyBase(object):
     :param primary_key: This property is a primary key
     :param is_collection: This property contains multiple values
     """
-    def __init__(self, name, primary_key=False, is_collection=False):
+    def __init__(self, name, primary_key=False, is_collection=False, is_computed_value=False):
         """
         :type name: str
         :type primary_key: bool
         """
         self.name = name
         self.primary_key = primary_key
         self.is_collection = is_collection
+        self.is_computed_value = is_computed_value
 
     def __repr__(self):
         return '<Property({0})>'.format(self.name)

odata/state.py

@@ -141,6 +141,9 @@ def data_for_update(self):
         update_data['@odata.type'] = self.entity.__odata_type__
 
         for _, prop in self.dirty_properties:
+            if prop.is_computed_value:
+                continue
+
             update_data[prop.name] = self.data[prop.name]
 
         for prop_name, prop in self.navigation_properties:
@@ -162,6 +165,9 @@ def _clean_new_entity(self, entity):
 
         es = entity.__odata__
         for _, prop in es.properties:
+            if prop.is_computed_value:
+                continue
+
             insert_data[prop.name] = es[prop.name]
 
         # Allow pk properties only if they have values

odata/tests/demo_metadata.xml

@@ -15,6 +15,9 @@
                 <Property Name="Category" Type="Edm.String"/>
                 <Property Name="Price" Type="Edm.Decimal"/>
                 <Property Name="ColorSelection" Type="d.ColorSelection"/>
+                <Property Name="ExampleComputed" Type="Edm.Int32">
+                    <Annotation Term="Org.OData.Core.V1.Computed" Bool="true" />
+                </Property>
             </EntityType>
             <EntityType Name="Manufacturer">
                 <Key>

odata/tests/test_metadata.py

@@ -2,7 +2,9 @@
 
 import os
 from unittest import TestCase
+import json
 
+import requests
 import responses
 
 from odata import ODataService
@@ -42,3 +44,26 @@ def test_read(self):
         self.assertIn('Manufacturer', Service.entities)
 
         self.assertIn('DemoUnboundAction', Service.actions)
+
+    def test_computed_value_in_insert(self):
+        with responses.RequestsMock() as rsps:
+            rsps.add(rsps.GET, 'http://demo.local/odata/$metadata/',
+                     body=metadata_xml, content_type='text/xml')
+            Service = ODataService('http://demo.local/odata/', reflect_entities=True)
+
+        Product = Service.entities['Product']
+        test_product = Product()
+
+        def request_callback_part(request):
+            payload = json.loads(request.body)
+            self.assertNotIn('ExampleComputed', payload)
+            headers = {}
+            return requests.codes.created, headers, json.dumps(payload)
+
+        with responses.RequestsMock() as rsps:
+            rsps.add_callback(
+                rsps.POST, Product.__odata_url__(),
+                callback=request_callback_part,
+                content_type='application/json',
+            )
+            Service.save(test_product)