Added abstract SecretField class for secret fields (#3717)

* Added abstract SecretField class for secret fields

* Added changes for changelog

changes/3409-expobrain.md

@@ -0,0 +1 @@
+Adds the `SecretField` abstract class so that all the current and future secret fields like `SecretStr` and `SecretBytes` will derive from it.

pydantic/__init__.py

@@ -110,6 +110,7 @@
     'DirectoryPath',
     'Json',
     'JsonWrapper',
+    'SecretField',
     'SecretStr',
     'SecretBytes',
     'StrictBool',

pydantic/types.py

@@ -1,3 +1,4 @@
+import abc
 import math
 import re
 import warnings
@@ -92,6 +93,7 @@
     'DirectoryPath',
     'Json',
     'JsonWrapper',
+    'SecretField',
     'SecretStr',
     'SecretBytes',
     'StrictBool',
@@ -812,7 +814,29 @@ def __modify_schema__(cls, field_schema: Dict[str, Any]) -> None:
 # ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ SECRET TYPES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 
-class SecretStr:
+class SecretField(abc.ABC):
+    """
+    Note: this should be implemented as a generic like `SecretField(ABC, Generic[T])`,
+          the `__init__()` should be part of the abstract class and the
+          `get_secret_value()` method should use the generic `T` type.
+
+          However Cython doesn't support very well generics at the moment and
+          the generated code fails to be imported (see
+          https://github.com/cython/cython/issues/2753).
+    """
+
+    def __eq__(self, other: Any) -> bool:
+        return isinstance(other, self.__class__) and self.get_secret_value() == other.get_secret_value()
+
+    def __str__(self) -> str:
+        return '**********' if self.get_secret_value() else ''
+
+    @abc.abstractmethod
+    def get_secret_value(self) -> Any:  # pragma: no cover
+        ...
+
+
+class SecretStr(SecretField):
     min_length: OptionalInt = None
     max_length: OptionalInt = None
 
@@ -845,12 +869,6 @@ def __init__(self, value: str):
     def __repr__(self) -> str:
         return f"SecretStr('{self}')"
 
-    def __str__(self) -> str:
-        return '**********' if self._secret_value else ''
-
-    def __eq__(self, other: Any) -> bool:
-        return isinstance(other, SecretStr) and self.get_secret_value() == other.get_secret_value()
-
     def __len__(self) -> int:
         return len(self._secret_value)
 
@@ -862,7 +880,7 @@ def get_secret_value(self) -> str:
         return self._secret_value
 
 
-class SecretBytes:
+class SecretBytes(SecretField):
     min_length: OptionalInt = None
     max_length: OptionalInt = None
 
@@ -895,12 +913,6 @@ def __init__(self, value: bytes):
     def __repr__(self) -> str:
         return f"SecretBytes(b'{self}')"
 
-    def __str__(self) -> str:
-        return '**********' if self._secret_value else ''
-
-    def __eq__(self, other: Any) -> bool:
-        return isinstance(other, SecretBytes) and self.get_secret_value() == other.get_secret_value()
-
     def __len__(self) -> int:
         return len(self._secret_value)
 

tests/test_types.py

@@ -75,6 +75,7 @@
     errors,
     validator,
 )
+from pydantic.types import SecretField
 from pydantic.typing import NoneType
 
 try:
@@ -2573,6 +2574,16 @@ class Foobar(BaseModel):
     ]
 
 
+def test_secretfield():
+    class Foobar(SecretField):
+        ...
+
+    message = "Can't instantiate abstract class Foobar with abstract methods? get_secret_value"
+
+    with pytest.raises(TypeError, match=message):
+        Foobar()
+
+
 def test_secretstr():
     class Foobar(BaseModel):
         password: SecretStr
@@ -2605,6 +2616,10 @@ class Foobar(BaseModel):
     assert f != f.copy(update=dict(password='4321'))
 
 
+def test_secretstr_is_secret_field():
+    assert issubclass(SecretStr, SecretField)
+
+
 def test_secretstr_equality():
     assert SecretStr('abc') == SecretStr('abc')
     assert SecretStr('123') != SecretStr('321')
@@ -2694,6 +2709,10 @@ class Foobar(BaseModel):
     assert f != f.copy(update=dict(password=b'4321'))
 
 
+def test_secretbytes_is_secret_field():
+    assert issubclass(SecretBytes, SecretField)
+
+
 def test_secretbytes_equality():
     assert SecretBytes(b'abc') == SecretBytes(b'abc')
     assert SecretBytes(b'123') != SecretBytes(b'321')