Use getattr and default for qualname

changes/5126-JensHeinrich.md

@@ -0,0 +1 @@
+Implement logic to support creating validators from non standard callables by using defaults to identify them and unwrapping `functools.partial` and `functools.partialmethod` when checking the signature.

pydantic/class_validators.py

@@ -1,6 +1,6 @@
 import warnings
 from collections import ChainMap
-from functools import wraps
+from functools import partial, partialmethod, wraps
 from itertools import chain
 from types import FunctionType
 from typing import TYPE_CHECKING, Any, Callable, Dict, Iterable, List, Optional, Set, Tuple, Type, Union, overload
@@ -147,7 +147,11 @@ def _prepare_validator(function: AnyCallable, allow_reuse: bool) -> 'AnyClassMet
     """
     f_cls = function if isinstance(function, classmethod) else classmethod(function)
     if not in_ipython() and not allow_reuse:
-        ref = f_cls.__func__.__module__ + '.' + f_cls.__func__.__qualname__
+        ref = (
+            getattr(f_cls.__func__, '__module__', '<default_module>')
+            + '.'
+            + getattr(f_cls.__func__, '__qualname__', '<default name>')
+        )
         if ref in _FUNCS:
             raise ConfigError(f'duplicate validator function "{ref}"; if this is intended, set `allow_reuse=True`')
         _FUNCS.add(ref)
@@ -165,14 +169,14 @@ def get_validators(self, name: str) -> Optional[Dict[str, Validator]]:
         if name != ROOT_KEY:
             validators += self.validators.get('*', [])
         if validators:
-            return {v.func.__name__: v for v in validators}
+            return {getattr(v.func, '__name__', '<default name>'): v for v in validators}
         else:
             return None
 
     def check_for_unused(self) -> None:
         unused_validators = set(
             chain.from_iterable(
-                (v.func.__name__ for v in self.validators[f] if v.check_fields)
+                (getattr(v.func, '__name__', '<default name>') for v in self.validators[f] if v.check_fields)
                 for f in (self.validators.keys() - self.used_validators)
             )
         )
@@ -243,8 +247,19 @@ def make_generic_validator(validator: AnyCallable) -> 'ValidatorCallable':
     """
     from inspect import signature
 
-    sig = signature(validator)
-    args = list(sig.parameters.keys())
+    if not isinstance(validator, (partial, partialmethod)):
+        # This should be the default case, so overhead is reduced
+        sig = signature(validator)
+        args = list(sig.parameters.keys())
+    else:
+        # Fix the generated argument lists of partial methods
+        sig = signature(validator.func)
+        args = [
+            k
+            for k in signature(validator.func).parameters.keys()
+            if k not in validator.args | validator.keywords.keys()
+        ]
+
     first_arg = args.pop(0)
     if first_arg == 'self':
         raise ConfigError(

tests/test_validators.py

@@ -1,8 +1,9 @@
 from collections import deque
 from datetime import datetime
 from enum import Enum
+from functools import partial, partialmethod
 from itertools import product
-from typing import Dict, List, Optional, Tuple, Union
+from typing import Any, Callable, Dict, List, Optional, Tuple, Union
 
 import pytest
 from typing_extensions import Literal
@@ -1345,3 +1346,32 @@ class Model(BaseModel):
         {'loc': ('foo',), 'msg': 'the list has duplicated items', 'type': 'value_error.list.unique_items'},
         {'loc': ('bar',), 'msg': 'the list has duplicated items', 'type': 'value_error.list.unique_items'},
     ]
+
+
+@pytest.mark.parametrize(
+    'func,allow_reuse',
+    [
+        pytest.param(partial, False, id='`partial` and check for reuse'),
+        pytest.param(partial, True, id='`partial` and ignore reuse'),
+        pytest.param(partialmethod, False, id='`partialmethod` and check for reuse'),
+        pytest.param(partialmethod, True, id='`partialmethod` and ignore reuse'),
+    ],
+)
+def test_functool_as_validator(
+    reset_tracked_validators,
+    func: Callable,
+    allow_reuse: bool,
+):
+    def custom_validator(
+        cls,
+        v: Any,
+        allowed: str,
+    ) -> Any:
+        assert v == allowed, f'Only {allowed} allowed as value; given: {v}'
+        return v
+
+    validate = func(custom_validator, allowed='TEXT')
+
+    class TestClass(BaseModel):
+        name: str
+        _custom_validate = validator('name', allow_reuse=allow_reuse)(validate)