Fix iterable selections for entity and collection requests

CHANGELOG.md

@@ -8,6 +8,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ### Fixed
 
+- service: serialize iterable selections as comma-separated fields for entity and collection requests, including wildcard selections (#71, #73).
+
 - service: `update_entity` accepts `200 OK` as well as `204 No Content`, so updates against services such as SAP SuccessFactors no longer raise `HttpError` (#136) - Sena Köse
 
 ## [1.12.1]

docs/usage/querying.rst

@@ -35,6 +35,19 @@ Print unique identification (Id) and last name of all employees:
         print(employee.EmployeeID, employee.LastName)
 
 
+Selecting properties
+--------------------
+
+Both single-entity and entity-set requests accept comma-separated text or an
+iterable of property names. Use ``'*'`` to request all properties, and ``None``
+to remove an existing selection:
+
+.. code-block:: python
+
+    employee = northwind.entity_sets.Employees.get_entity(1).select(['EmployeeID', 'LastName']).execute()
+    employees = northwind.entity_sets.Employees.get_entities().select('*').execute()
+
+
 Get entities matching a filter
 ------------------------------
 

pyodata/v2/service.py

@@ -26,6 +26,13 @@
 HTTP_CODE_NO_CONTENT = 204
 
 
+def _normalize_select(select):
+    """Convert an iterable of selection clauses to its query representation."""
+    if select is None or isinstance(select, str):
+        return select
+    return ','.join(select)
+
+
 def urljoin(*path):
     """Joins the passed string parts into a one string url"""
 
@@ -397,9 +404,9 @@ def nav(self, nav_property):
     def select(self, select):
         """Specifies a subset of properties to return.
 
-           @param select  a comma-separated list of selection clauses
+           @param select  comma-separated text or an iterable of selection clauses
         """
-        self._select = select
+        self._select = _normalize_select(select)
         return self
 
     def expand(self, expand):
@@ -710,8 +717,8 @@ def order_by(self, order_by):
         return self
 
     def select(self, select):
-        """Sets the selection clauses."""
-        self._select = select
+        """Sets selection clauses from comma-separated text or an iterable."""
+        self._select = _normalize_select(select)
         return self
 
     def skip(self, skip):

tests/test_service_v2.py

@@ -19,6 +19,48 @@
 URL_ROOT = 'http://odatapy.example.com'
 
 
+@pytest.mark.parametrize('single', [False, True])
+@pytest.mark.parametrize('make_selection', [list, tuple, iter])
+def test_select_iterable(service, single, make_selection):
+    """Iterable selections are serialized as one comma-separated query value."""
+    request = (service.entity_sets.Employees.get_entity(23) if single
+               else service.entity_sets.Employees.get_entities())
+    assert request.select(make_selection(['NameFirst', 'NameLast'])) is request
+    assert request.get_query_params()['$select'] == 'NameFirst,NameLast'
+    # A generator must not be consumed again while building another request.
+    assert request.get_query_params()['$select'] == 'NameFirst,NameLast'
+
+
+@pytest.mark.parametrize('single', [False, True])
+def test_select_string_and_reset(service, single):
+    """String selections and clearing an existing selection remain supported."""
+    request = (service.entity_sets.Employees.get_entity(23) if single
+               else service.entity_sets.Employees.get_entities())
+    assert request.select('NameFirst,NameLast') is request
+    assert request.get_query_params()['$select'] == 'NameFirst,NameLast'
+    assert request.select(None) is request
+    assert '$select' not in request.get_query_params()
+
+
+@pytest.mark.parametrize('single', [False, True])
+@pytest.mark.parametrize('selection', ['*', ['*'], ('*',), {'*'}])
+def test_select_wildcard(service, single, selection):
+    """Both request types preserve the OData all-properties selection."""
+    request = (service.entity_sets.Employees.get_entity(23) if single
+               else service.entity_sets.Employees.get_entities())
+    assert request.select(selection) is request
+    assert request.get_query_params()['$select'] == '*'
+
+
+@pytest.mark.parametrize('single', [False, True])
+def test_select_set(service, single):
+    """Unordered selection inputs retain every requested property."""
+    request = (service.entity_sets.Employees.get_entity(23) if single
+               else service.entity_sets.Employees.get_entities())
+    request.select({'NameFirst', 'NameLast'})
+    assert set(request.get_query_params()['$select'].split(',')) == {'NameFirst', 'NameLast'}
+
+
 @pytest.fixture
 def service(schema):
     """Service fixture"""
@@ -3204,4 +3246,4 @@ def hook(response):
 
 def test_service_without_response_hook_works(service):
     """response_hook defaults to None and does not affect normal operation"""
-    assert service.response_hook is None
+    assert service.response_hook is None