[116] Support Callable default and Always Use default If Present (#…

…117)

* [#116] Call field default when it is callable

- Also, always generate default value if `field.default` is supplied
  - Previously, this would not happen, since the `generator` determination
    was being done earlier in the same `if, elif` block

- Add unit tests for generating default value of callables of varying kinds

* [116] Add a unit test to cover kwarg over attr_mapping

* [116] Reduce complexity of custom field class

* [116] Update CHANGELOG

Co-authored-by: Bernardo Fontes <[email protected]>

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ### Changed
 - Fixed _model parameter annotations [PR #115](https://github.com/model-bakers/model_bakery/pull/115)
+- Fixes bug when field has callable `default` [PR #117](https://github.com/model-bakers/model_bakery/pull/117)
 - [dev] Drop Python 3.5 support as it is retired (https://www.python.org/downloads/release/python-3510/)
 
 ### Removed

model_bakery/baker.py

@@ -515,7 +515,11 @@ def generate_value(self, field: Field, commit: bool = True) -> Any:
             self._remote_field(field).model, contenttypes.models.ContentType
         )
 
-        if field.name in self.attr_mapping:
+        if field.has_default():
+            if callable(field.default):
+                return field.default()
+            return field.default
+        elif field.name in self.attr_mapping:
             generator = self.attr_mapping[field.name]
         elif getattr(field, "choices"):
             generator = random_gen.gen_from_choices(field.choices)
@@ -525,8 +529,6 @@ def generate_value(self, field: Field, commit: bool = True) -> Any:
             generator = generators.get(field.__class__)
         elif field.__class__ in self.type_mapping:
             generator = self.type_mapping[field.__class__]
-        elif field.has_default():
-            return field.default
         else:
             raise TypeError("%s is not supported by baker." % field.__class__)
 

tests/generic/models.py

@@ -10,6 +10,7 @@
 from django.contrib.contenttypes.fields import GenericForeignKey, GenericRelation
 from django.contrib.contenttypes.models import ContentType
 from django.core.files.storage import FileSystemStorage
+from django.utils.timezone import now
 
 from model_bakery.gis import BAKER_GIS
 from model_bakery.timezone import smart_datetime as datetime
@@ -265,6 +266,10 @@ class DummyBlankFieldsModel(models.Model):
     blank_text_field = models.TextField(max_length=300, blank=True)
 
 
+class ExtendedDefaultField(models.IntegerField):
+    pass
+
+
 class DummyDefaultFieldsModel(models.Model):
     default_id = models.AutoField(primary_key=True)
     default_char_field = models.CharField(max_length=50, default="default")
@@ -279,6 +284,9 @@ class DummyDefaultFieldsModel(models.Model):
     )
     default_email_field = models.EmailField(default="[email protected]")
     default_slug_field = models.SlugField(default="a-slug")
+    default_unknown_class_field = ExtendedDefaultField(default=42)
+    default_callable_int_field = models.IntegerField(default=lambda: 12)
+    default_callable_datetime_field = models.DateTimeField(default=now)
 
 
 class DummyFileFieldModel(models.Model):

tests/test_baker.py

@@ -542,6 +542,15 @@ def test_fill_optional_with_integer(self):
         with pytest.raises(TypeError):
             baker.make(models.DummyBlankFieldsModel, _fill_optional=1)
 
+    def test_fill_optional_with_default(self):
+        dummy = baker.make(models.DummyDefaultFieldsModel, _fill_optional=True)
+        assert dummy.default_callable_int_field == 12
+        assert isinstance(dummy.default_callable_datetime_field, datetime.datetime)
+
+    def test_fill_optional_with_default_unknown_class(self):
+        dummy = baker.make(models.DummyDefaultFieldsModel, _fill_optional=True)
+        assert dummy.default_unknown_class_field == 42
+
 
 @pytest.mark.django_db
 class TestFillAutoFieldsTestCase:
@@ -572,6 +581,9 @@ def test_skip_fields_with_default(self):
         assert dummy.default_decimal_field == Decimal("0")
         assert dummy.default_email_field == "[email protected]"
         assert dummy.default_slug_field == "a-slug"
+        assert dummy.default_unknown_class_field == 42
+        assert dummy.default_callable_int_field == 12
+        assert isinstance(dummy.default_callable_datetime_field, datetime.datetime)
 
 
 @pytest.mark.django_db

tests/test_extending_bakery.py

@@ -28,6 +28,7 @@ class SadPeopleBaker(baker.Baker):
     attr_mapping = {
         "enjoy_jards_macale": gen_opposite,
         "like_metal_music": gen_opposite,
+        "name": gen_opposite,  # Use a field without `default`
     }
 
 
@@ -53,8 +54,13 @@ def test_string_to_generator_required(self):
         like_metal_music_field = Person._meta.get_field("like_metal_music")
         sad_people_factory = SadPeopleBaker(Person)
         person = sad_people_factory.make()
-        assert person.enjoy_jards_macale is not enjoy_jards_macale_field.default
-        assert person.like_metal_music is not like_metal_music_field.default
+        assert person.enjoy_jards_macale is enjoy_jards_macale_field.default
+        assert person.like_metal_music is like_metal_music_field.default
+
+    def test_kwarg_used_over_attr_mapping_generator(self):
+        sad_people_factory = SadPeopleBaker(Person)
+        person = sad_people_factory.make(name="test")
+        assert person.name == "test"
 
     @pytest.mark.parametrize("value", [18, 18.5, [], {}, True])
     def test_fail_pass_non_string_to_generator_required(self, value):