$ cat fastapi/week/2026-09-07.log
the week in review · Sep 7 – Sep 13, 2026
Pydantic ships TypeForm support and MISSING stabilization
By RepoJournal · composed from the cited sources · human-reviewed weekly · methodology
A week of core schema work also brought a deque schema, enum constructor fixes, and fixes for datetime constraints.
Add support for `TypeForm` pydantic/pydantic
TypeForm support closes multiple long-standing issues, letting typed forms be expressed directly in models instead of workarounds. If you have been using TypeAdapter or custom hooks to represent a type itself, this is the built-in path.
Stabilize `MISSING` sentinel pydantic/pydantic
The MISSING sentinel is now stable, closing the tracking issue for its behavior. Code that imports MISSING or relies on its identity in defaults and validators can treat it as a fixed part of the public surface.
Call enum constructors in both validation modes pydantic/pydantic
After the pydantic-core change, enum constructors were only called in one path; this makes them run in both validation modes. If your enums define __init__ logic, its behavior no longer depends on which mode validation takes.
Add a `deque` core schema pydantic/pydantic
A deque core schema means constraints can finally be applied to deque fields, which previously fell through to the base collection handling. If you have been validating deques with len or item constraints, that now works as expected.
Fix supported constraints for types of `datetime` module (#13768) pydantic/pydantic
The datetime module's supported constraints were narrowed to what actually applies to each type. Schemas that declared constraints on datetime, date, or time fields incorrectly will now be rejected or adjusted at build time.
Fix inconsistencies between constraints and core schemas allowed values (#13772) pydantic/pydantic
Constraints and core schemas could disagree about allowed values; this aligns them. If you generate JSON Schema from models with constrained fields, the schema and the runtime validator now agree.
Fix Mypy plugin crash with import cycle pydantic/pydantic
The Mypy plugin crash with an import cycle is fixed, which unblocks type checking for projects where the plugin previously aborted. Python type-checking runs in CI on affected layouts should no longer fail with an internal error.
Add an enterprise support guide pydantic/pydantic
The enterprise support guide documents support boundaries, escalation, upgrade paths, architecture reviews, and response commitments. Teams depending on Pydantic in production now have a written reference for what paid support covers, pending the linked docs change.
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