tree-wide: correctly handle null values

Only a declared property knows if it accepts Null or not. I was playing
with nullable Type but than I would have to have also nullable
TypeTraits and there result would be a complete mess. Therefore I decided
to move the responsibility to serialize/deserialize the declared
property. The decision led to a simpler code which is a good sign.

I could have used a better exception type but we currently evaluating
the best exception strategies, so I used a generic type.

Part of the issue #95

CHANGELOG.md

@@ -17,6 +17,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - removed superfluous debug print when parsing FunctionImports from metadata - Jakub Filak
 - property 'Nullable' attributes are correctly parsed and respected - Vasilii Khomutov
 - use correct type of deserialization of Literal (URL) structure values - Jakub Filak
+- null values are correctly handled - Jakub Filak
 
 ## [1.4.0]
 

pyodata/v2/model.py

@@ -287,7 +287,7 @@ def to_literal(edm_type, value):
         result = {}
         for type_prop in edm_type.proprties():
             if type_prop.name in value:
-                result[type_prop.name] = type_prop.typ.traits.to_literal(value[type_prop.name])
+                result[type_prop.name] = type_prop.to_literal(value[type_prop.name])
 
         return result
 
@@ -301,7 +301,7 @@ def from_json(edm_type, value):
         result = {}
         for type_prop in edm_type.proprties():
             if type_prop.name in value:
-                result[type_prop.name] = type_prop.typ.traits.from_json(value[type_prop.name])
+                result[type_prop.name] = type_prop.from_json(value[type_prop.name])
 
         return result
 
@@ -315,7 +315,7 @@ def from_literal(edm_type, value):
         result = {}
         for type_prop in edm_type.proprties():
             if type_prop.name in value:
-                result[type_prop.name] = type_prop.typ.traits.from_literal(value[type_prop.name])
+                result[type_prop.name] = type_prop.from_literal(value[type_prop.name])
 
         return result
 
@@ -711,6 +711,42 @@ def precision(self):
     def scale(self):
         return self._scale
 
+    def from_literal(self, value):
+        if value is None:
+            if not self.nullable:
+                raise PyODataException(f'Cannot convert null URL literal to value of {str(self)}')
+
+            return None
+
+        return self.typ.traits.from_literal(value)
+
+    def to_literal(self, value):
+        if value is None:
+            if not self.nullable:
+                raise PyODataException(f'Cannot convert None to URL literal of {str(self)}')
+
+            return None
+
+        return self.typ.traits.to_literal(value)
+
+    def from_json(self, value):
+        if value is None:
+            if not self.nullable:
+                raise PyODataException(f'Cannot convert null JSON to value of {str(self)}')
+
+            return None
+
+        return self.typ.traits.from_json(value)
+
+    def to_json(self, value):
+        if value is None:
+            if not self.nullable:
+                raise PyODataException(f'Cannot convert None to JSON of {str(self)}')
+
+            return None
+
+        return self.typ.traits.to_json(value)
+
     def _check_scale_value(self):
         if self._scale > self._precision:
             raise PyODataModelError('Scale value ({}) must be less than or equal to precision value ({})'

pyodata/v2/service.py

@@ -204,15 +204,15 @@ def to_key_string_without_parentheses(self):
         if self._type == EntityKey.TYPE_SINGLE:
             # first property is the key property
             key_prop = self._key[0]
-            return key_prop.typ.traits.to_literal(self._proprties[key_prop.name])
+            return key_prop.to_literal(self._proprties[key_prop.name])
 
         key_pairs = []
         for key_prop in self._key:
             # if key_prop.name not in self.__dict__['_cache']:
             #    raise RuntimeError('Entity key is not complete, missing value of property: {0}'.format(key_prop.name))
 
             key_pairs.append(
-                '{0}={1}'.format(key_prop.name, key_prop.typ.traits.to_literal(self._proprties[key_prop.name])))
+                '{0}={1}'.format(key_prop.name, key_prop.to_literal(self._proprties[key_prop.name])))
 
         return ','.join(key_pairs)
 
@@ -456,7 +456,7 @@ def _build_values(entity_type, entity):
         values = {}
         for key, val in entity.items():
             try:
-                val = entity_type.proprty(key).typ.traits.to_json(val)
+                val = entity_type.proprty(key).to_json(val)
             except KeyError:
                 try:
                     nav_prop = entity_type.nav_proprty(key)
@@ -543,7 +543,7 @@ def set(self, **kwargs):
 
         for key, val in kwargs.items():
             try:
-                val = self._entity_type.proprty(key).typ.traits.to_json(val)
+                val = self._entity_type.proprty(key).to_json(val)
             except KeyError:
                 raise PyODataException(
                     'Property {} is not declared in {} entity type'.format(key, self._entity_type.name))
@@ -679,7 +679,7 @@ def parameter(self, name, value):
             param = self._function_import.get_parameter(name)
 
             # add parameter as custom query argument
-            self.custom(param.name, param.typ.traits.to_literal(value))
+            self.custom(param.name, param.to_literal(value))
         except KeyError:
             raise PyODataException('Function import {0} does not have pararmeter {1}'
                                    .format(self._function_import.name, name))
@@ -721,11 +721,10 @@ def __init__(self, service, entity_set, entity_type, proprties=None, entity_key=
             for type_proprty in self._entity_type.proprties():
                 if type_proprty.name in proprties:
                     if proprties[type_proprty.name] is not None:
-                        self._cache[type_proprty.name] = type_proprty.typ.traits.from_json(proprties[type_proprty.name])
+                        self._cache[type_proprty.name] = type_proprty.from_json(proprties[type_proprty.name])
                     else:
                         # null value is in literal form for now, convert it to python representation
-                        self._cache[type_proprty.name] = type_proprty.typ.traits.from_literal(
-                            type_proprty.typ.null_value)
+                        self._cache[type_proprty.name] = type_proprty.from_literal(type_proprty.typ.null_value)
 
             # then, assign all navigation properties
             for prop in self._entity_type.nav_proprties:
@@ -843,7 +842,7 @@ def proprty_get_handler(key, proprty, response):
                                 .format(proprty.name, key, response.status_code), response)
 
             data = response.json()['d']
-            return proprty.typ.traits.from_json(data[proprty.name])
+            return proprty.from_json(data[proprty.name])
 
         path = urljoin(self.get_path(), name)
         return self._service.http_get_odata(
@@ -942,7 +941,7 @@ def or_(*operands):
     def format_filter(proprty, operator, value):
         """Creates a filter expression """
 
-        return '{} {} {}'.format(proprty.name, operator, proprty.typ.traits.to_literal(value))
+        return '{} {} {}'.format(proprty.name, operator, proprty.to_literal(value))
 
     def __eq__(self, value):
         return GetEntitySetFilter.format_filter(self._proprty, 'eq', value)

tests/test_model_v2_EdmStructTypeSerializer.py

@@ -0,0 +1,99 @@
+"""Tests of OData Model: class VariableDeclaration"""
+
+import pytest
+import datetime
+from pyodata.v2.model import EdmStructTypeSerializer, Types, StructType, StructTypeProperty
+from pyodata.exceptions import PyODataException
+
+
+@pytest.fixture
+def complex_type_property_declarations():
+    return {
+        'TestString': (Types.parse_type_name('Edm.String'), "'FooBar'", "'FooBar'", 'FooBar'),
+        'TestBoolean': (Types.parse_type_name('Edm.Boolean'), False, 'false', False),
+        'TestInt64': (Types.parse_type_name('Edm.Int64'), '123L', '123L', 123),
+        'TestDateTime': (Types.parse_type_name('Edm.DateTime'), "/Date(2147483647000)/", "datetime'2038-01-19T3:14:7'",
+                         datetime.datetime(2038, 1, 19, hour=3, minute=14, second=7, tzinfo=datetime.timezone.utc))
+    }
+
+
+def define_complex_type(complex_type_property_declarations, nullable = True):
+    complex_typ = StructType('TestComplexType', 'Label Complex Type', False)
+
+    for name, prop_decl in complex_type_property_declarations.items():
+        prop = StructTypeProperty(name, prop_decl[0], nullable, None, None, None,
+            None, None, None, None, None, None, None, None, None, None, None, None)
+
+        prop.typ = Types.from_name(prop.type_info.name)
+        complex_typ._properties[prop.name] = prop
+        prop.struct_type = complex_typ
+
+    return complex_typ
+
+
+@pytest.fixture
+def complex_type_with_nullable_props(complex_type_property_declarations, nullable = True):
+    return define_complex_type(complex_type_property_declarations, nullable=True)
+
+
+@pytest.fixture
+def complex_type_without_nullable_props(complex_type_property_declarations, nullable = True):
+    return define_complex_type(complex_type_property_declarations, nullable=False)
+
+
+def test_nullable_from_json_null_properties(complex_type_with_nullable_props, complex_type_property_declarations):
+    entity_json = { prop_name: None for prop_name in complex_type_property_declarations.keys() }
+
+    entity_odata = complex_type_with_nullable_props.traits.from_json(entity_json)
+
+    assert entity_json.keys() == entity_odata.keys()
+
+    for name, value in entity_odata.items():
+        assert value is None, f'Property: {name}'
+
+
+def test_non_nullable_from_json_null_properties(complex_type_without_nullable_props, complex_type_property_declarations):
+    for prop_name in complex_type_property_declarations.keys():
+        entity_json = { prop_name : None }
+        with pytest.raises(PyODataException):
+            entity_odata = complex_type_without_nullable_props.traits.from_json(entity_json)
+
+
+def test_non_nullable_from_json(complex_type_without_nullable_props, complex_type_property_declarations):
+    entity_json = { prop_name : prop_decl[1] for prop_name, prop_decl in complex_type_property_declarations.items() }
+
+    entity_odata =complex_type_without_nullable_props.traits.from_json(entity_json)
+
+    assert entity_json.keys() == entity_odata.keys()
+
+    for name, value in entity_odata.items():
+        assert value == complex_type_property_declarations[name][3], f'Value of {name}'
+
+
+def test_nullable_from_literal_null_properties(complex_type_with_nullable_props, complex_type_property_declarations):
+    entity_literal = { prop_name: None for prop_name in complex_type_property_declarations.keys() }
+
+    entity_odata = complex_type_with_nullable_props.traits.from_literal(entity_literal)
+
+    assert entity_literal.keys() == entity_odata.keys()
+
+    for name, value in entity_odata.items():
+        assert value is None, f'Property: {name}'
+
+
+def test_non_nullable_from_literal_null_properties(complex_type_without_nullable_props, complex_type_property_declarations):
+    for prop_name in complex_type_property_declarations.keys():
+        entity_literal = { prop_name : None }
+        with pytest.raises(PyODataException):
+            entity_odata = complex_type_without_nullable_props.traits.from_literal(entity_literal)
+
+
+def test_non_nullable_from_literal(complex_type_without_nullable_props, complex_type_property_declarations):
+    entity_literal = { prop_name : prop_decl[2] for prop_name, prop_decl in complex_type_property_declarations.items() }
+
+    entity_odata =complex_type_without_nullable_props.traits.from_literal(entity_literal)
+
+    assert entity_literal.keys() == entity_odata.keys()
+
+    for name, value in entity_odata.items():
+        assert value == complex_type_property_declarations[name][3], f'Value of {name}'

tests/test_model_v2_VariableDeclaration.py

@@ -0,0 +1,74 @@
+"""Tests of OData Model: class VariableDeclaration"""
+
+import pytest
+from pyodata.v2.model import VariableDeclaration, Types
+from pyodata.exceptions import PyODataException
+
+
+@pytest.fixture
+def variable_of_string_nullable():
+    variable = VariableDeclaration('TestVariable', Types.parse_type_name('Edm.String'), True, None, None, None)
+    variable.typ = Types.from_name(variable.type_info.name)
+    return variable
+
+@pytest.fixture
+def variable_of_string():
+    variable = VariableDeclaration('TestVariable', Types.parse_type_name('Edm.String'), False, None, None, None)
+    variable.typ = Types.from_name(variable.type_info.name)
+    return variable
+
+
+def test_variable_of_string_nullable_from_json_none(variable_of_string_nullable):
+    assert variable_of_string_nullable.from_json(None) is None
+
+
+def test_variable_of_string_nullable_to_json_none(variable_of_string_nullable):
+    assert variable_of_string_nullable.to_json(None) is None
+
+
+def test_variable_of_string_nullable_from_literal_none(variable_of_string_nullable):
+    assert variable_of_string_nullable.from_literal(None) is None
+
+
+def test_variable_of_string_nullable_to_literal_none(variable_of_string_nullable):
+    assert variable_of_string_nullable.to_literal(None) is None
+
+
+def test_variable_of_string_nullable_from_json_non_none(variable_of_string_nullable):
+    assert variable_of_string_nullable.from_json('FromJSON') == 'FromJSON'
+
+
+def test_variable_of_string_nullable_to_json(variable_of_string_nullable):
+    assert variable_of_string_nullable.to_json('ToJSON') == 'ToJSON'
+
+
+def test_variable_of_string_nullable_from_literal(variable_of_string_nullable):
+    assert variable_of_string_nullable.from_literal("'FromLiteral'") == 'FromLiteral'
+
+
+def test_variable_of_string_nullable_to_literal(variable_of_string_nullable):
+    assert variable_of_string_nullable.to_literal('ToLiteral') == "'ToLiteral'"
+
+
+def test_variable_of_string_from_json_none(variable_of_string):
+    with pytest.raises(PyODataException) as e_info:
+        variable_of_string.from_json(None)
+    assert str(e_info.value).startswith('Cannot convert null JSON to value of VariableDeclaration(TestVariable)')
+
+
+def test_variable_of_string_to_json_none(variable_of_string):
+    with pytest.raises(PyODataException) as e_info:
+        variable_of_string.to_json(None)
+    assert str(e_info.value).startswith('Cannot convert None to JSON of VariableDeclaration(TestVariable)')
+
+
+def test_variable_of_string_from_literal_none(variable_of_string):
+    with pytest.raises(PyODataException) as e_info:
+        variable_of_string.from_literal(None)
+    assert str(e_info.value).startswith('Cannot convert null URL literal to value of VariableDeclaration(TestVariable)')
+
+
+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)')