✨ Add a config field to make all model fields optional

changes/3121-christophelec.md

@@ -0,0 +1 @@
+Add a `total` configuration field to create models with all fields Optional

docs/usage/model_config.md

@@ -115,6 +115,10 @@ not be included in the model schemas. **Note**: this means that attributes on th
 **`copy_on_model_validation`**
 : whether or not inherited models used as fields should be reconstructed (copied) on validation instead of being kept untouched (default: `True`)
 
+**`total`**
+: whether all fields must be present in the model. Setting this to `False` is equivalent to manually setting all fields as `Optional` with a `None` default (default: `True`)
+
+
 ## Change behaviour globally
 
 If you wish to change the behaviour of _pydantic_ globally, you can create your own custom `BaseModel`

pydantic/config.py

@@ -62,6 +62,7 @@ class BaseConfig:
     json_dumps: Callable[..., str] = json.dumps
     json_encoders: Dict[Type[Any], AnyCallable] = {}
     underscore_attrs_are_private: bool = False
+    total: bool = True
 
     # Whether or not inherited models as fields should be reconstructed as base model
     copy_on_model_validation: bool = True
@@ -96,7 +97,9 @@ def prepare_field(cls, field: 'ModelField') -> None:
         """
         Optional hook to check or modify fields during model creation.
         """
-        pass
+        if not cls.total:
+            field.type_ = Optional[field.type_]
+            field.required = False
 
 
 def inherit_config(self_config: 'ConfigType', parent_config: 'ConfigType', **namespace: Any) -> 'ConfigType':

tests/test_create_model.py

@@ -205,3 +205,23 @@ class Config:
 
     m2 = create_model('M2', __config__=Config, a=(str, Field(...)))
     assert m2.schema()['properties'] == {'a': {'title': 'A', 'description': 'descr', 'type': 'string'}}
+
+
+def test_config_all_optional_fields_model():
+    class Config:
+        total = False
+
+    m1 = create_model('M1', __config__=Config, a=(str, ...))
+    assert m1()
+
+
+def test_config_all_optional_fields_model_inheritance():
+    class TestBase(BaseModel):
+        b: str
+
+    class Test(TestBase, total=False):
+        a: str
+
+    with pytest.raises(ValidationError):
+        TestBase()
+    assert Test()