Skip extra/unknown fields checks when using from_attributes=True (#537)

Author: adriangb

src/lookup_key.rs

@@ -478,7 +478,7 @@ impl PathItem {
 }
 
 /// wrapper around `getattr` that returns `Ok(None)` for attribute errors, but returns other errors
-/// We dont check `try_from_attributes` because that check was performed on the top level object before we got here
+/// We don't check `try_from_attributes` because that check was performed on the top level object before we got here
 fn py_get_attrs<'a>(obj: &'a PyAny, attr_name: &Py<PyString>) -> PyResult<Option<&'a PyAny>> {
     match obj.getattr(attr_name.extract::<&PyString>(obj.py())?) {
         Ok(attr) => Ok(Some(attr)),

src/validators/typed_dict.rs

@@ -156,8 +156,9 @@ impl Validator for TypedDictValidator {
 
         // we only care about which keys have been used if we're iterating over the object for extra after
         // the first pass
-        let mut used_keys: Option<AHashSet<&str>> = match self.extra_behavior {
-            ExtraBehavior::Allow | ExtraBehavior::Forbid => Some(AHashSet::with_capacity(self.fields.len())),
+        let mut used_keys: Option<AHashSet<&str>> = match (&self.extra_behavior, &dict) {
+            (_, GenericMapping::PyGetAttr(_, _)) => None,
+            (ExtraBehavior::Allow | ExtraBehavior::Forbid, _) => Some(AHashSet::with_capacity(self.fields.len())),
             _ => None,
         };
 

tests/validators/test_typed_dict.py

@@ -3,7 +3,7 @@
 import sys
 from dataclasses import dataclass
 from datetime import datetime
-from typing import Any, Dict, Mapping, Union
+from typing import Any, Dict, List, Mapping, Union
 
 import pytest
 from dirty_equals import FunctionCheck, HasRepr, IsStr
@@ -1192,13 +1192,55 @@ class MyDataclass:
         }
     )
 
-    assert v.validate_python(Foobar()) == ({'a': 1, 'b': 2, 'c': 'ham'}, {'a', 'b', 'c'})
-    assert v.validate_python(MyDataclass()) == ({'a': 1, 'b': 2, 'c': 'ham'}, {'a', 'b', 'c'})
-    assert v.validate_python(Cls(a=1, b=2, c='ham')) == ({'a': 1, 'b': 2, 'c': 'ham'}, {'a', 'b', 'c'})
-    assert v.validate_python(Cls(a=1, b=datetime(2000, 1, 1))) == ({'a': 1, 'b': datetime(2000, 1, 1)}, {'a', 'b'})
+    assert v.validate_python(Foobar()) == ({'a': 1}, {'a'})
+    assert v.validate_python(MyDataclass()) == ({'a': 1}, {'a'})
+    assert v.validate_python(Cls(a=1, b=2, c='ham')) == ({'a': 1}, {'a'})
+    assert v.validate_python(Cls(a=1, b=datetime(2000, 1, 1))) == ({'a': 1}, {'a'})
     assert v.validate_python(Cls(a=1, b=datetime.now, c=lambda: 42)) == ({'a': 1}, {'a'})
 
 
+def test_from_attributes_extra_ignore_no_attributes_accessed() -> None:
+    v = SchemaValidator(
+        {
+            'type': 'typed-dict',
+            'fields': {'a': {'type': 'typed-dict-field', 'schema': {'type': 'int'}}},
+            'from_attributes': True,
+            'extra_behavior': 'ignore',
+        }
+    )
+
+    accessed: List[str] = []
+
+    class Source:
+        a = 1
+        b = 2
+
+        def __getattribute__(self, __name: str) -> Any:
+            accessed.append(__name)
+            return super().__getattribute__(__name)
+
+    assert v.validate_python(Source()) == {'a': 1}
+    assert 'a' in accessed and 'b' not in accessed
+
+
+def test_from_attributes_extra_forbid() -> None:
+    class Source:
+        a = 1
+        b = 2
+
+    v = SchemaValidator(
+        {
+            'type': 'typed-dict',
+            'return_fields_set': True,
+            'fields': {'a': {'type': 'typed-dict-field', 'schema': {'type': 'int'}}},
+            'from_attributes': True,
+            'extra_behavior': 'forbid',
+        }
+    )
+
+    assert v.validate_python(Source()) == ({'a': 1}, {'a'})
+
+
 def foobar():
     pass