[database][view] Fix output to named tuple member retrieval

This allows to properly initialise and use database views that
uses python keywords as output name.

Fixes #16

beat/backend/python/data.py

@@ -563,11 +563,13 @@ class DatabaseOutputDataSource(DataSource):
         end = None
         previous_value = None
 
+        attribute = self.view.get_output_mapping(output_name)
+
         for index, obj in enumerate(objects):
             if start is None:
                 start = index
-                previous_value = getattr(obj, output_name)
-            elif getattr(obj, output_name) != previous_value:
+                previous_value = getattr(obj, attribute)
+            elif getattr(obj, attribute) != previous_value:
                 end = index - 1
                 previous_value = None
 
@@ -576,7 +578,7 @@ class DatabaseOutputDataSource(DataSource):
                     self.infos.append(Infos(start_index=start, end_index=end))
 
                 start = index
-                previous_value = getattr(obj, output_name)
+                previous_value = getattr(obj, attribute)
 
         end = index
 

beat/backend/python/database.py

@@ -186,6 +186,9 @@ class Runner(object):
         return loader.run(self.obj, 'get', self.exc, output, index)
 
 
+    def get_output_mapping(self, output):
+        return loader.run(self.obj, 'get_output_mapping', self.exc, output)
+
     def objects(self):
         return self.obj.objs
 
@@ -523,6 +526,15 @@ class Database(object):
 
 class View(object):
 
+
+    def __init__(self):
+        #  Current databases definitions uses named tuple to store information.
+        #  This has one limitation, python keywords like `class` cannot be used.
+        #  output_member_map allows to use that kind of keyword as output name
+        #  while using something different for the named tuple (for example cls,
+        #  klass, etc.)
+        self.output_member_map = {}
+
     def index(self, root_folder, parameters):
         """Returns a list of (named) tuples describing the data provided by the view.
 
@@ -591,6 +603,12 @@ class View(object):
         raise NotImplementedError
 
 
+    def get_output_mapping(self, output):
+        """Returns the object member to use for given output if any otherwise
+        the member name is the output name.
+        """
+        return self.output_member_map.get(output, output)
+
 # ----------------------------------------------------------
 
 

beat/backend/python/test/prefix/databases/integers_db/1.json

@@ -12,7 +12,8 @@
                     "outputs": {
                         "a": "user/single_integer/1",
                         "b": "user/single_integer/1",
-                        "sum": "user/single_integer/1"
+                        "sum": "user/single_integer/1",
+                        "class": "user/single_integer/1"
                     }
                 }
             ]
@@ -29,7 +30,8 @@
                         "a": "user/single_integer/1",
                         "b": "user/single_integer/1",
                         "c": "user/single_integer/1",
-                        "sum": "user/single_integer/1"
+                        "sum": "user/single_integer/1",
+                        "class": "user/single_integer/1"
                     }
                 }
             ]
@@ -45,7 +47,8 @@
                     "outputs": {
                         "a": "user/single_integer/1",
                         "b": "user/single_integer/1",
-                        "sum": "user/single_integer/1"
+                        "sum": "user/single_integer/1",
+                        "class": "user/single_integer/1"
                     }
                 },
                 {
@@ -56,7 +59,8 @@
                         "a": "user/single_integer/1",
                         "b": "user/single_integer/1",
                         "c": "user/single_integer/1",
-                        "sum": "user/single_integer/1"
+                        "sum": "user/single_integer/1",
+                        "class": "user/single_integer/1"
                     }
                 }
             ]

beat/backend/python/test/prefix/databases/integers_db/1.py

@@ -32,20 +32,23 @@ from beat.backend.python.database import View
 
 
 class Double(View):
+    def __init__(self):
+        super(Double, self)
+        self.output_member_map = {'class': 'cls'}
 
     def index(self, root_folder, parameters):
-        Entry = namedtuple('Entry', ['a', 'b', 'sum'])
+        Entry = namedtuple('Entry', ['a', 'b', 'sum', 'cls'])
 
         return [
-            Entry(1, 10, 11),
-            Entry(2, 20, 22),
-            Entry(3, 30, 33),
-            Entry(4, 40, 44),
-            Entry(5, 50, 55),
-            Entry(6, 60, 66),
-            Entry(7, 70, 77),
-            Entry(8, 80, 88),
-            Entry(9, 90, 99),
+            Entry(1, 10, 11, 41),
+            Entry(2, 20, 22, 42),
+            Entry(3, 30, 33, 43),
+            Entry(4, 40, 44, 44),
+            Entry(5, 50, 55, 45),
+            Entry(6, 60, 66, 46),
+            Entry(7, 70, 77, 47),
+            Entry(8, 80, 88, 48),
+            Entry(9, 90, 99, 49),
         ]
 
 
@@ -66,6 +69,10 @@ class Double(View):
             return {
                 'value': numpy.int32(obj.sum)
             }
+        elif output == 'class':
+            return {
+                'value': numpy.int32(obj.cls)
+            }
 
 
 #----------------------------------------------------------

beat/backend/python/test/test_data.py

@@ -397,7 +397,7 @@ class TestDatabaseOutputDataSource(unittest.TestCase):
         view.setup(os.path.join(self.cache_root, 'data.db'), pack=False)
 
         self.assertTrue(view.data_sources is not None)
-        self.assertEqual(len(view.data_sources), 3)
+        self.assertEqual(len(view.data_sources), 4)
 
         for output_name, data_source in view.data_sources.items():
             self.assertEqual(9, len(data_source))

beat/backend/python/test/test_database.py

@@ -68,11 +68,12 @@ def test_load_protocol_with_one_set():
     set = database.set("double", "double")
 
     nose.tools.eq_(set['name'], 'double')
-    nose.tools.eq_(len(set['outputs']), 3)
+    nose.tools.eq_(len(set['outputs']), 4)
 
     assert set['outputs']['a'] is not None
     assert set['outputs']['b'] is not None
     assert set['outputs']['sum'] is not None
+    assert set['outputs']['class'] is not None
 
 
 #----------------------------------------------------------
@@ -88,18 +89,20 @@ def test_load_protocol_with_two_sets():
     set = database.set("two_sets", "double")
 
     nose.tools.eq_(set['name'], 'double')
-    nose.tools.eq_(len(set['outputs']), 3)
+    nose.tools.eq_(len(set['outputs']), 4)
 
     assert set['outputs']['a'] is not None
     assert set['outputs']['b'] is not None
     assert set['outputs']['sum'] is not None
+    assert set['outputs']['class'] is not None
 
     set = database.set("two_sets", "triple")
 
     nose.tools.eq_(set['name'], 'triple')
-    nose.tools.eq_(len(set['outputs']), 4)
+    nose.tools.eq_(len(set['outputs']), 5)
 
     assert set['outputs']['a'] is not None
     assert set['outputs']['b'] is not None
     assert set['outputs']['c'] is not None
     assert set['outputs']['sum'] is not None
+    assert set['outputs']['class'] is not None
\ No newline at end of file

beat/backend/python/test/test_database_view.py

@@ -121,7 +121,7 @@ class TestDatabaseViewRunner(unittest.TestCase):
         view.setup(os.path.join(self.cache_root, 'data.db'))
 
         self.assertTrue(view.data_sources is not None)
-        self.assertEqual(len(view.data_sources), 3)
+        self.assertEqual(len(view.data_sources), 4)
 
         for i in range(0, 9):
             self.assertEqual(view.get('a', i)['value'], i + 1)