JSON serialisation error with Secret types union.

[KasperZutterman]

Initial Checks

• I confirm that I'm using Pydantic V2

Description

A PydanticSerializationError is raised when attempting model_dump_json() on a model containing a union of Secret types.

Error: pydantic_core._pydantic_core.PydanticSerializationError: Error serializing to JSON: PydanticSerializationError: Unable to serialize unknown type: <class 'pydantic.types.Secret'>

Example Code

from pydantic import BaseModel, Secret


class Base(BaseModel):
    x: Secret[int] | Secret[str]


model = Base(x=1)

print(model.model_dump())  # No error
print(model.model_dump_json())  # pydantic_core._pydantic_core.PydanticSerializationError: Error serializing to JSON: PydanticSerializationError: Unable to serialize unknown type: <class 'pydantic.types.Secret'>

Python, Pydantic & OS Version

pydantic version: 2.7.0
        pydantic-core version: 2.18.1
          pydantic-core build: profile=release pgo=true
                 install path: /Users/kasperzutterman/.pyenv/versions/3.12.1/envs/pydantic-3.12/lib/python3.12/site-packages/pydantic
               python version: 3.12.1 (main, Feb  2 2024, 09:13:09) [Clang 15.0.0 (clang-1500.1.0.2.5)]
                     platform: macOS-14.4.1-arm64-arm-64bit
             related packages: typing_extensions-4.9.0
                       commit: unknown

[sydney-runkle]

@KasperZutterman,

Thanks for reporting this! Definitely something that we want to fix. Will release a fix for this early next week with 2.7.1!

[sydney-runkle]

^^ I've opened #9240 to address this issue :).