Configuration correctness tests on ModelSerializer

rest_framework/serializers.py

@@ -10,7 +10,7 @@ python primitives.
 2. The process of marshalling between python primitives and request and
 response content is handled by parsers and renderers.
 """
-from django.core.exceptions import ValidationError
+from django.core.exceptions import ImproperlyConfigured, ValidationError
 from django.db import models
 from django.utils import six
 from django.utils.datastructures import SortedDict
@@ -358,6 +358,7 @@ class ModelSerializer(Serializer):
         model = getattr(self.Meta, 'model')
         fields = getattr(self.Meta, 'fields', None)
         depth = getattr(self.Meta, 'depth', 0)
+        extra_kwargs = getattr(self.Meta, 'extra_kwargs', {})
 
         # Retrieve metadata about fields & relationships on the model class.
         info = model_meta.get_field_info(model)
@@ -405,9 +406,32 @@ class ModelSerializer(Serializer):
                     if not issubclass(field_cls, HyperlinkedRelatedField):
                         kwargs.pop('view_name', None)
 
-            else:
-                assert False, 'Field name `%s` is not valid.' % field_name
+            elif hasattr(model, field_name):
+                # Create a read only field for model methods and properties.
+                field_cls = ReadOnlyField
+                kwargs = {}
 
+            else:
+                raise ImproperlyConfigured(
+                    'Field name `%s` is not valid for model `%s`.' %
+                    (field_name, model.__class__.__name__)
+                )
+
+            # Check that any fields declared on the class are
+            # also explicity included in `Meta.fields`.
+            missing_fields = set(declared_fields.keys()) - set(fields)
+            if missing_fields:
+                missing_field = list(missing_fields)[0]
+                raise ImproperlyConfigured(
+                    'Field `%s` has been declared on serializer `%s`, but '
+                    'is missing from `Meta.fields`.' %
+                    (missing_field, self.__class__.__name__)
+                )
+
+            # Populate any kwargs defined in `Meta.extra_kwargs`
+            kwargs.update(extra_kwargs.get(field_name, {}))
+
+            # Create the serializer field.
             ret[field_name] = field_cls(**kwargs)
 
         return ret

tests/test_model_serializer.py

@@ -5,6 +5,7 @@ shortcuts for automatically creating serializers based on a given model class.
 These tests deal with ensuring that we correctly map the model fields onto
 an appropriate set of serializer fields for each case.
 """
+from django.core.exceptions import ImproperlyConfigured
 from django.db import models
 from django.test import TestCase
 from rest_framework import serializers
@@ -37,6 +38,9 @@ class RegularFieldsModel(models.Model):
     time_field = models.TimeField()
     url_field = models.URLField(max_length=100)
 
+    def method(self):
+        return 'method'
+
 
 class TestRegularFieldMappings(TestCase):
     def test_regular_fields(self):
@@ -69,6 +73,87 @@ class TestRegularFieldMappings(TestCase):
 
         self.assertEqual(repr(TestSerializer()), expected)
 
+    def test_method_field(self):
+        """
+        Properties and methods on the model should be allowed as `Meta.fields`
+        values, and should map to `ReadOnlyField`.
+        """
+        class TestSerializer(serializers.ModelSerializer):
+            class Meta:
+                model = RegularFieldsModel
+                fields = ('auto_field', 'method')
+
+        expected = dedent("""
+            TestSerializer():
+                auto_field = IntegerField(read_only=True)
+                method = ReadOnlyField()
+        """)
+        self.assertEqual(repr(TestSerializer()), expected)
+
+    def test_pk_fields(self):
+        """
+        Both `pk` and the actual primary key name are valid in `Meta.fields`.
+        """
+        class TestSerializer(serializers.ModelSerializer):
+            class Meta:
+                model = RegularFieldsModel
+                fields = ('pk', 'auto_field')
+
+        expected = dedent("""
+            TestSerializer():
+                pk = IntegerField(label='Auto field', read_only=True)
+                auto_field = IntegerField(read_only=True)
+        """)
+        self.assertEqual(repr(TestSerializer()), expected)
+
+    def test_extra_field_kwargs(self):
+        """
+        Ensure `extra_kwargs` are passed to generated fields.
+        """
+        class TestSerializer(serializers.ModelSerializer):
+            class Meta:
+                model = RegularFieldsModel
+                fields = ('pk', 'char_field')
+                extra_kwargs = {'char_field': {'default': 'extra'}}
+
+        expected = dedent("""
+            TestSerializer():
+                pk = IntegerField(label='Auto field', read_only=True)
+                char_field = CharField(default='extra', max_length=100)
+        """)
+        self.assertEqual(repr(TestSerializer()), expected)
+
+    def test_invalid_field(self):
+        """
+        Field names that do not map to a model field or relationship should
+        raise a configuration errror.
+        """
+        class TestSerializer(serializers.ModelSerializer):
+            class Meta:
+                model = RegularFieldsModel
+                fields = ('auto_field', 'invalid')
+
+        with self.assertRaises(ImproperlyConfigured) as excinfo:
+            TestSerializer()
+        expected = 'Field name `invalid` is not valid for model `ModelBase`.'
+        assert str(excinfo.exception) == expected
+
+    def test_missing_field(self):
+        class TestSerializer(serializers.ModelSerializer):
+            missing = serializers.ReadOnlyField()
+
+            class Meta:
+                model = RegularFieldsModel
+                fields = ('auto_field',)
+
+        with self.assertRaises(ImproperlyConfigured) as excinfo:
+            TestSerializer()
+        expected = (
+            'Field `missing` has been declared on serializer '
+            '`TestSerializer`, but is missing from `Meta.fields`.'
+        )
+        assert str(excinfo.exception) == expected
+
 
 # Testing relational field mappings