Pydantic validation. Check that a string does not contain certain characters

Question

I need to make sure that the string does not contain Cyrillic characters. I check like this:

from pydantic import BaseModel, Field

class MyModel(BaseModel):
    content_en: str = Field(pattern=r"[^а-яА-Я]")


data = MyModel(content_en="Has wrong content 'йцукен'")
print(data)
>>> content_en="Has wrong content 'йцукен'"

But when I pass strings containing Cyrillic alphabet into the content_en field, an error is not raised.
Expected:

pydantic_core._pydantic_core.ValidationError: 1 validation error for MyModel
...

How to check correctly?
Python 3.8
Pydantic 2.5

Solution (thanks @chepner):

class MyModel(BaseModel):
    content_en: str = Field(pattern=r"^[^а-яА-ЯёЁ]*$")

Answer 1

Your pattern matches any string containing at least one non-Cyrillic character, not a string consisting solely of non-Cyrillic characters.

>>> MyModel(content_en="Has wrong content 'йцукен'")
MyModel(content_en="Has wrong content 'йцукен'")
>>> MyModel(content_en="йцукен")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/chepner/py311/lib/python3.11/site-packages/pydantic/main.py", line 164, in __init__
    __pydantic_self__.__pydantic_validator__.validate_python(data, self_instance=__pydantic_self__)
pydantic_core._pydantic_core.ValidationError: 1 validation error for MyModel
content_en
  String should match pattern '[^а-яА-Я]' [type=string_pattern_mismatch, input_value='йцукен', input_type=str]
    For further information visit https://errors.pydantic.dev/2.5/v/string_pattern_mismatch

The correct pattern is ^[^а-яА-Я]*$:

>>> class MyModel(BaseModel):
...     content_en: str = Field(pattern=r"^[^а-яА-Я]*$")
...
>>> MyModel(content_en="Has wrong content 'йцукен'")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/chepner/py311/lib/python3.11/site-packages/pydantic/main.py", line 164, in __init__
    __pydantic_self__.__pydantic_validator__.validate_python(data, self_instance=__pydantic_self__)
pydantic_core._pydantic_core.ValidationError: 1 validation error for MyModel
content_en
  String should match pattern '^[^а-яА-Я]*$' [type=string_pattern_mismatch, input_value="Has wrong content 'йцукен'", input_type=str]
    For further information visit https://errors.pydantic.dev/2.5/v/string_pattern_mismatch