pydantic v2.13.0b1

This is the first beta release of the 2.13 version, mainly providing bug fixes and performance improvements for validation and serialization.

Notable changes include:

• Add a new polymorphic_serialization option, solving issues with serialize_as_any introduced in 2.12.
• Latest V1.10.26 release under the pydantic.v1 namespace. This version includes support for Python 3.14.
• The pydantic-core repository was merged inside the main pydantic one.

What's Changed

Packaging

• Bump Rust url dependency from 2.5.4 to 2.5.7 in pydantic-core by @dependabot[bot] in #12508
• Bump Rust minimum version to 1.88, use edition 2024 by @davidhewitt and @Viicos in #12551 and #12752
• Bump PyO3 to 0.28, jiter to 0.13 by @davidhewitt in #12767

New Features

• Add polymorphic_serialization option by @davidhewitt in #12518
• Support Root models with Literal root types as discriminator field types by @YassinNouh21 in #12680

Changes

• Migrate pydantic-core CI by @Viicos in #12752
• Import pydantic-core into pydantic by @davidhewitt in #12481
• Backport V1 changes up to v1.10.26 by @Viicos in #12663
• Use the complex() constructor unconditionally when validating complex Python data by @tanmaymunjal in #12498
• Add support for three-tuple input for Decimal by @tanmaymunjal in #12500
• Align @field_serializer logic with @field_validator by @Viicos in #12577
• Make PydanticUserError a RuntimeError instead of a TypeError by @poliakovva in #12579
• Remove redundant serialization attempts in nested unions by @davidhewitt in #12604
• Copy root value when making root model shallow copies by @YassinNouh21 in #12679
• Ensure deterministic JSON schema defaults by sorting sets by @drshvik in #12760

Performance

• Refactor DecoratorInfos.build() implementation by @Viicos in #12536
• Cache compiled regex in pydantic-core by @Viicos in #12549
• Optimize creation of Literal validators by @davidhewitt in #12569
• Optimize implementation of LookupKey by @davidhewitt in #12571
• Use python strings for field names by @davidhewitt in #12631
• Optimize datetime formatting code by @davidhewitt in #12626
• Validate JSON model data by iteration by @davidhewitt in #12550
• Optimize annotations evaluation of Pydantic models by @Viicos in #12681
• Optimize FieldInfo._copy() by @Viicos in #12727

Fixes

• Fix FieldInfo rebuilding when parameterizing generic models with an Annotated type by @Viicos in #12463
• Fix nested model schema deduplication in JSON schema generation by @marwan-alloreview in #12494
• Fix InitVar being ignored when using with the pydantic.Field() function by @Viicos in #12495
• Fix support for enums with NamedTuple as values by @Viicos in #12506
• Do not delete mock validator/serializer in rebuild_dataclass() by @Viicos in #12513
• Require test suite to pass with free threading, switch back to global generic types cache by @davidhewitt in #12537
• Refactor __pydantic_extra__ annotation handling by @Viicos in #12563
• Do not add claim of UUID "safety" provision by @davidhewitt in #12567
• Use Python hash to perform lookup in tagged union serializer by @davidhewitt in #12594
• Do not emit serialization warning MISSING sentinel is present in a nested model by @Viicos in #12635
• Do not eagerly evaluate annotations in signature logic by @Viicos in #12660
• Fix serialization of typed dict unions when exclude_none is set by @davidhewitt in #12677
• Do not reuse prebuilt serializers/validators on rebuilds by @lmmx in #12689
• Fix type annotation of field_definitions in create_model() by @lehmann-hqs in #12734
• Fix incorrect dataclass constructor signature when overriding class kw_only with Field() by @jfadia in #12741
• Use typing.Union when replacing types under Python 3.14 by @Viicos in #12733
• Improve ImportString error when internal imports fail by @tsembp in #12740
• Fix serializing complex numbers with negative zero imaginary part by @lhnwrk in #12770
• Preserve custom docstrings on stdlib dataclasses in JSON schema by @nightcityblade in #12815

New Contributors

• @marwan-alloreview made their first contribution in #12494
• @tanmaymunjal made their first contribution in #12498
• @poliakovva made their first contribution in #12579
• @lehmann-hqs made their first contribution in #12734
• @jfadia made their first contribution in #12741
• @tsembp made their first contribution in #12740
• @drshvik made their first contribution in #12760
• @lhnwrk made their first contribution in #12770
• @nightcityblade made their first contribution in #12815