Set additionalProperties to False on Extra.forbid models

changes/796-Code0x58.rst

@@ -0,0 +1 @@
+Set ``additionalProperties`` to false in schema for models with extra fields disallowed.

pydantic/schema.py

@@ -593,6 +593,8 @@ def model_type_schema(
         out_schema = {'type': 'object', 'properties': properties}
         if required:
             out_schema['required'] = required
+    if model.__config__.extra == 'forbid':
+        out_schema['additionalProperties'] = False
     return out_schema, definitions, nested_models
 
 

tests/test_schema.py

@@ -11,7 +11,7 @@
 
 import pytest
 
-from pydantic import BaseModel, Schema, ValidationError, validator
+from pydantic import BaseModel, Extra, Schema, ValidationError, validator
 from pydantic.color import Color
 from pydantic.networks import AnyUrl, EmailStr, IPvAnyAddress, IPvAnyInterface, IPvAnyNetwork, NameEmail, stricturl
 from pydantic.schema import (
@@ -1475,3 +1475,19 @@ class Config:
         'required': ['a'],
         'examples': [{'a': 'Foo'}],
     }
+
+
+def test_model_with_extra_forbidden():
+    class Model(BaseModel):
+        a: str
+
+        class Config:
+            extra = Extra.forbid
+
+    assert Model.schema() == {
+        'title': 'Model',
+        'type': 'object',
+        'properties': {'a': {'title': 'A', 'type': 'string'}},
+        'required': ['a'],
+        'additionalProperties': False,
+    }