From 66d9348078e9f50a8984cf9f1fd298124843ba9e Mon Sep 17 00:00:00 2001
From: Hasan Ramezani <hasan.r67@gmail.com>
Date: Thu, 11 Aug 2022 23:53:32 +0200
Subject: [PATCH] Add support for `re.Pattern`

---
 changes/4366-hramezani.md |  1 +
 pydantic/fields.py        |  3 ++-
 pydantic/validators.py    |  2 +-
 tests/test_types.py       | 10 ++++++----
 4 files changed, 10 insertions(+), 6 deletions(-)
 create mode 100644 changes/4366-hramezani.md

diff --git a/changes/4366-hramezani.md b/changes/4366-hramezani.md
new file mode 100644
index 00000000000..a70bedab388
--- /dev/null
+++ b/changes/4366-hramezani.md
@@ -0,0 +1 @@
+Add support for `re.Pattern`
diff --git a/pydantic/fields.py b/pydantic/fields.py
index 917798d7261..e8c15aa609e 100644
--- a/pydantic/fields.py
+++ b/pydantic/fields.py
@@ -1,4 +1,5 @@
 import copy
+import re
 from collections import Counter as CollectionCounter, defaultdict, deque
 from collections.abc import Callable, Hashable as CollectionsHashable, Iterable as CollectionsIterable
 from typing import (
@@ -595,7 +596,7 @@ def _type_analysis(self) -> None:  # noqa: C901 (ignore complexity)
                 self.required = False
             self.allow_none = True
             return
-        elif self.type_ is Pattern:
+        elif self.type_ is Pattern or self.type_ is re.Pattern:
             # python 3.7 only, Pattern is a typing object but without sub fields
             return
         elif is_literal_type(self.type_):
diff --git a/pydantic/validators.py b/pydantic/validators.py
index 052edd3e436..59933a0d8c2 100644
--- a/pydantic/validators.py
+++ b/pydantic/validators.py
@@ -684,7 +684,7 @@ def find_validators(  # noqa: C901 (ignore complexity)
     if is_none_type(type_):
         yield none_validator
         return
-    if type_ is Pattern:
+    if type_ is Pattern or type_ is re.Pattern:
         yield pattern_validator
         return
     if type_ is Hashable or type_ is CollectionsHashable:
diff --git a/tests/test_types.py b/tests/test_types.py
index 425bf9d02c9..b9ec8128ff8 100644
--- a/tests/test_types.py
+++ b/tests/test_types.py
@@ -2540,9 +2540,10 @@ class JsonRequired(BaseModel):
     assert JsonRequired().dict() == {'json_obj': None}
 
 
-def test_pattern():
+@pytest.mark.parametrize('pattern_type', [re.Pattern, Pattern])
+def test_pattern(pattern_type):
     class Foobar(BaseModel):
-        pattern: Pattern
+        pattern: pattern_type
 
     f = Foobar(pattern=r'^whatev.r\d$')
     assert f.pattern.__class__.__name__ == 'Pattern'
@@ -2563,9 +2564,10 @@ class Foobar(BaseModel):
     }
 
 
-def test_pattern_error():
+@pytest.mark.parametrize('pattern_type', [re.Pattern, Pattern])
+def test_pattern_error(pattern_type):
     class Foobar(BaseModel):
-        pattern: Pattern
+        pattern: pattern_type
 
     with pytest.raises(ValidationError) as exc_info:
         Foobar(pattern='[xx')