Base64Bytes field doesn't raises validation error for min_length constraint

[kirillklimenko]

Initial Checks

• I confirm that I'm using Pydantic V2

Description

The validation should raise an error due to the minimum length constraint set for the data field in the Test model. However, no validation error is raised even though the data field is empty.

Expected Behavior:

Passing empty data for the data field should raise a validation error due to the minimum length constraint set in the Test model.

Actual Behavior:

No validation error is raised when passing empty data for the data field.

Steps to Reproduce:

Define the provided models in a Pydantic-based Python script.
Attempt to validate input data where the data field is empty.
Notice that no validation error is raised even though the data field does not meet the minimum length constraint.
Additional Information:
This behavior was observed in Pydantic version 2.6.4.

Example Code

from pydantic import Base64Bytes, BaseModel, Field


class Test(BaseModel):
    data: Base64Bytes = Field(min_length=10)


test = Test(data=b"")  # no validation error

Python, Pydantic & OS Version

pydantic version: 2.6.4
pydantic-core version: 2.16.3
pydantic-core build: profile=release pgo=true
python version: 3.10.11 (tags/v3.10.11:7d4cc5a, Apr  5 2023, 00:38:17) [MSC v.1929 64 bit (AMD64)]
platform: Windows-10-10.0.22631-SP0

[ShahriyarR]

The same behavior is true for versions:

$ pip freeze | grep pydantic
pydantic==2.7.0
pydantic_core==2.18.1

[sydney-runkle]

@kirillklimenko,

Thanks for reporting, definitely a bug! PRs welcome with a fix!