model: correctly parse Nullable attribute values

As pointed out in the issue:
 - true or missing attribute means Nullable
 - false means non Nullable

For our convenience when writing tests, Python True/False support added.

Closes #98

Author: filak-sap

CHANGELOG.md

@@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ### Changed
 - handle GET EntitySet payload without the member results - Jakub Filak
 - both Literal and JSON DateTimes has Timezone set to UTC - Jakub Filak
+- properties without the attribute Nullable accepts null values - Jakub Filak
 
 ### Fixed
 - removed superfluous debug print when parsing FunctionImports from metadata - Jakub Filak

pyodata/v2/model.py

@@ -647,7 +647,9 @@ def __init__(self, name, type_info, nullable, max_length, precision, scale):
         self._type_info = type_info
         self._typ = None
 
-        self._nullable = bool(nullable)
+        self._nullable = nullable is None or \
+            (isinstance(nullable, str) and nullable.lower() == 'true') or \
+            (isinstance(nullable, bool) and nullable)
 
         if not max_length:
             self._max_length = None

tests/metadata.xml

@@ -205,6 +205,8 @@
                 <FunctionImport Name="retrieve" ReturnType="Edm.Boolean" EntitySet="MasterEntities" m:HttpMethod="GET"
                                 sap:action-for="EXAMPLE_SRV.MasterEntity">
                     <Parameter Name="Param" Type="Edm.String" Mode="In" MaxLenght="5"/>
+                    <Parameter Name="ParamNonNull" Type="Edm.String" Mode="In" MaxLenght="5" Nullable="false"/>
+                    <Parameter Name="ParamNull" Type="Edm.String" Mode="In" MaxLenght="5" Nullable="true"/>
                 </FunctionImport>
                 <FunctionImport Name="refresh" m:HttpMethod="GET"/>
                 <AssociationSet Name="toDataEntitySet" Association="EXAMPLE_SRV.toDataEntity" sap:creatable="false"
@@ -303,6 +305,7 @@
                 <Property Name="ID" Type="Edm.Int32" Nullable="false"/>
                 <Property Name="NameFirst" Type="Edm.String" Nullable="true"/>
                 <Property Name="NameLast" Type="Edm.String" Nullable="true"/>
+                <Property Name="NickName" Type="Edm.String"/>
                 <NavigationProperty Name="Addresses" Relationship="EXAMPLE_SRV_SETS.AssociationEmployeeAddress"
                                     FromRole="EmployeeRole" ToRole="AddressRole"/>
             </EntityType>

tests/test_model_v2.py

@@ -81,6 +81,7 @@ def test_edmx(schema):
     assert master_prop_data.text_proprty.name == 'DataName'
     assert master_prop_data.visible
     assert master_prop_data.max_length == StructTypeProperty.MAXIMUM_LENGTH
+    assert master_prop_data.nullable == False
 
     master_prop_data_vh = master_prop_data.value_helper
     assert str(master_prop_data_vh) == 'ValueHelper(MasterEntity/Data)'
@@ -147,6 +148,19 @@ def test_edmx(schema):
     assert typ_ex_info.value.args[0] == 'Type FooBar does not exist in Schema Namespace EXAMPLE_SRV'
 
 
+def test_schema_entity_type_nullable(schema):
+    emp_entity = schema.entity_type('Employee')
+
+    id_property = emp_entity.proprty('ID')
+    assert id_property.nullable == False
+
+    firstname_property = emp_entity.proprty('NameFirst')
+    assert firstname_property.nullable == True
+
+    nickname_property = emp_entity.proprty('NickName')
+    assert nickname_property.nullable == True
+
+
 def test_schema_entity_sets(schema):
     """Test Schema methods for EntitySets"""
 
@@ -282,12 +296,18 @@ def test_edmx_function_imports(schema):
     assert str(param) == 'FunctionImportParameter(Param)'
     assert param.name == 'Param'
     assert param.typ.name == 'Edm.String'
-    assert not param.nullable
+    assert param.nullable
     assert param.max_length is None
     assert param.mode == 'In'
     assert param.typ.traits.to_literal('Foo') == "'Foo'"
     assert param.typ.traits.from_literal("'Foo'") == 'Foo'
 
+    param_non_null = function_import.parameters[1]
+    assert param_non_null.nullable == False
+
+    param_null = function_import.parameters[2]
+    assert param_null.nullable == True
+
     # function import without return type
     function_import = schema.function_import('refresh')
     assert function_import.return_type is None

tests/test_model_v2_VariableDeclaration.py

@@ -72,3 +72,28 @@ def test_variable_of_string_to_literal_none(variable_of_string):
     with pytest.raises(PyODataException) as e_info:
         variable_of_string.to_literal(None)
     assert str(e_info.value).startswith('Cannot convert None to URL literal of VariableDeclaration(TestVariable)')
+
+
+def test_variable_nullable_init_param_None():
+    variable = VariableDeclaration('TestVariable', Types.parse_type_name('Edm.String'), None, None, None, None)
+    assert variable.nullable == True
+
+
+def test_variable_nullable_init_param_str_true():
+    variable = VariableDeclaration('TestVariable', Types.parse_type_name('Edm.String'), 'true', None, None, None)
+    assert variable.nullable == True
+
+
+def test_variable_nullable_init_param_str_false():
+    variable = VariableDeclaration('TestVariable', Types.parse_type_name('Edm.String'), 'false', None, None, None)
+    assert variable.nullable == False
+
+
+def test_variable_nullable_init_param_bool_true():
+    variable = VariableDeclaration('TestVariable', Types.parse_type_name('Edm.String'), True, None, None, None)
+    assert variable.nullable == True
+
+
+def test_variable_nullable_init_param_bool_false():
+    variable = VariableDeclaration('TestVariable', Types.parse_type_name('Edm.String'), False, None, None, None)
+    assert variable.nullable == False