Ellipsis does not mark annotated field as required in create_model

[jackmpcollins]

Initial Checks

• I confirm that I'm using Pydantic V2

Description

Ellipsis is being recognized as a default value for fields that have Annotated[<type>, Field()] type annotation. These fields should instead be marked as required with no default.

This works correctly in v2.1.0 and is broken in v2.1.1 and in the latest version v2.5.3.

This is mainly an issue for me using create_model where Ellipsis must be used to indicate the absence of a default value.

Relevant docs https://docs.pydantic.dev/latest/concepts/models/#required-fields

Example Code

from typing import Annotated
from pydantic import BaseModel, Field


class Model(BaseModel):
    a: int = ...
    b: Annotated[int, "placeholder"] = ...
    c: Annotated[int, Field()] = ...

for f in Model.model_fields.items():
    print(f)

# v2.1.0
# ('a', FieldInfo(annotation=int, required=True))
# ('b', FieldInfo(annotation=int, required=True, metadata=['placeholder']))
# ('c', FieldInfo(annotation=int, required=True))

# v2.1.1
# ('a', FieldInfo(annotation=int, required=True))
# ('b', FieldInfo(annotation=int, required=True, metadata=['placeholder']))
# ('c', FieldInfo(annotation=int, required=False, default=Ellipsis))


# ---


from typing import Annotated
from pydantic import Field, create_model


m = create_model(
    "Test",
    a=(int, ...),
    b=(Annotated[int, "placeholder"], ...),
    c=(Annotated[int, Field()], ...),
)
for f in m.model_fields.items():
    print(f)

# v2.1.0
# ('a', FieldInfo(annotation=int, required=True))
# ('b', FieldInfo(annotation=int, required=True, metadata=['placeholder']))
# ('c', FieldInfo(annotation=int, required=True))

# v2.1.1
# ('a', FieldInfo(annotation=int, required=True))
# ('b', FieldInfo(annotation=int, required=True, metadata=['placeholder']))
# ('c', FieldInfo(annotation=int, required=False, default=Ellipsis))

Python, Pydantic & OS Version

pydantic version: 2.5.3
        pydantic-core version: 2.14.6
          pydantic-core build: profile=release pgo=true
                 install path: /Users/jack/Code/magentic/.venv/lib/python3.10/site-packages/pydantic
               python version: 3.10.8 (main, Apr  2 2023, 18:27:17) [Clang 14.0.3 (clang-1403.0.22.14.1)]
                     platform: macOS-14.2.1-arm64-arm-64bit
             related packages: typing_extensions-4.7.1 pydantic-settings-2.0.3 mypy-1.8.0

[jackmpcollins]

There was minimal change from v2.1.0 to v2.1.1 so hopefully the cause should be easy to identify for someone familiar with the code. v2.1.0...v2.1.1

[sydney-runkle]

@jackmpcollins,

Thanks for reporting this. This does look like a bug. We'll look to fix this for v2.7!

[Evenfire]

@sydney-runkle

I just had a quick look. The symptoms are similar too #8629 but this is indeed a bug. As @jackmpcollins pointed out, the changes introduced between 2.1.0 and 2.1.1 are the source.

Just a few details:
With those changes, applying the overrides bypasses the FieldInfo.__init__ method where the default attribute is set to a special value when the default parameter value is.... You guessed it: Ellipsis.

I'll open a PR

[sydney-runkle]

@Evenfire,

Fantastic! Ping me when you need a review 🚀 !

[sydney-runkle]

I think this was the change that caused the bug in the first place: https://github.com/pydantic/pydantic/pull/6862/files

[dmarteau]

Is the fix released ?

As with version 2.6.3 this appears not yet fixed:

class Foo(BaseModel):
    x: Annotated[int, Field()] = ...
   
from f in Foo.model_fields.items():
    print(f)

# 2.6.3
# ('x', FieldInfo(annotation=int, required=False, default=Ellipsis))

Thanks

[sydney-runkle]

It's fixed on main, and should be released in v2.7.0!