#16: Possibility to mark filed as required.

README.rst

@@ -3,6 +3,16 @@ Domain models
 
 Domain models framework for Python projects
 
+============
+
+.. image:: https://travis-ci.org/ets-labs/domain_models.svg?branch=master
+    :target: https://travis-ci.org/ets-labs/domain_models
+    :alt: Build Status
+
+.. image:: https://coveralls.io/repos/github/ets-labs/domain_models/badge.svg?branch=master
+    :target: https://coveralls.io/github/ets-labs/domain_models?branch=master
+    :alt: Coverage Status
+
 Introduction
 ~~~~~~~~~~~~
 

domain_models/fields.py

@@ -10,7 +10,7 @@
 class Field(property):
     """Base field."""
 
-    def __init__(self, default=None):
+    def __init__(self, default=None, required=False):
         """Initializer."""
         super(Field, self).__init__(self.get_value, self.set_value)
         self.name = None
@@ -19,6 +19,7 @@ def __init__(self, default=None):
         self.model_cls = None
 
         self.default = default
+        self.required = required
 
     def bind_name(self, name):
         """Bind field to its name in model class."""
@@ -40,8 +41,12 @@ def bind_model_cls(self, model_cls):
 
     def init_model(self, model, value):
         """Init model with field."""
-        if not value:
+        if value is None:
             value = self.default() if callable(self.default) else self.default
+
+        if value is None and self.required:
+            raise AttributeError("This field is required.")
+
         setattr(model, self.storage_name, value)
 
     def get_value(self, model):
@@ -50,6 +55,9 @@ def get_value(self, model):
 
     def set_value(self, model, value):
         """Set field's value."""
+        if value is None and self.required:
+            raise AttributeError("This field is required.")
+
         if value is not None:
             value = self._converter(value)
         setattr(model, self.storage_name, value)
@@ -122,9 +130,9 @@ def _converter(self, value):
 class Model(Field):
     """Model relation field."""
 
-    def __init__(self, related_model_cls, default=None):
+    def __init__(self, related_model_cls, default=None, required=False):
         """Initializer."""
-        super(Model, self).__init__(default=default)
+        super(Model, self).__init__(default=default, required=required)
 
         self.related_model_cls = related_model_cls
 
@@ -140,9 +148,9 @@ def _converter(self, value):
 class Collection(Field):
     """Models collection relation field."""
 
-    def __init__(self, related_model_cls, default=None):
+    def __init__(self, related_model_cls, default=None, required=False):
         """Initializer."""
-        super(Collection, self).__init__(default=default)
+        super(Collection, self).__init__(default=default, required=required)
         self.related_model_cls = related_model_cls
 
     def _converter(self, value):

tests/test_fields.py

@@ -22,6 +22,7 @@ class ExampleModel(models.DomainModel):
     field = fields.Field()
     field_default = fields.Field(default=123)
     field_default_callable = fields.Field(default=time.time)
+    field_required_default = fields.Field(default=123, required=True)
 
     bool_field = fields.Bool()
 
@@ -38,6 +39,11 @@ class ExampleModel(models.DomainModel):
     collection_field = fields.Collection(RelatedModel)
 
 
+class RequiredFieldModel(models.DomainModel):
+    """Example model for required fields."""
+    field_required = fields.Field(required=True)
+
+
 class FieldTest(unittest.TestCase):
     """Base field tests."""
 
@@ -81,6 +87,37 @@ def test_field_default_callable(self):
         self.assertGreater(model2.field_default_callable,
                            model1.field_default_callable)
 
+    def test_field_required(self):
+        """Test required field with default value."""
+        model = ExampleModel()
+        self.assertEquals(model.field_required_default, 123)
+
+    def test_field_required_set_valid(self):
+        """Test required field with valid value."""
+        model = ExampleModel()
+        model.field_required_default = False
+        self.assertIs(model.field_required_default, False)
+
+    def test_field_required_set_invalid(self):
+        """Test required field with invalid value."""
+        model = ExampleModel()
+        with self.assertRaises(AttributeError):
+            model.field_required_default = None
+
+    def test_field_required_init_valid_model(self):
+        """Test required field with valid value as model keyword."""
+        model = RequiredFieldModel(field_required=False)
+        self.assertIs(model.field_required, False)
+        model.field_required = 123
+        self.assertEqual(model.field_required, 123)
+
+    def test_field_required_init_invalid_model(self):
+        """Test required field with invalid value as model keyword."""
+        with self.assertRaises(AttributeError):
+            RequiredFieldModel()
+        with self.assertRaises(AttributeError):
+            RequiredFieldModel(field_required=None)
+
 
 class BoolTest(unittest.TestCase):
     """Bool field tests."""