First-class Pydantic v2+ support

[patrick91]

Summary

Add first-class support for Pydantic v2+ models in Strawberry GraphQL.

This PR introduces a new strawberry.pydantic module that allows you to directly decorate Pydantic BaseModel classes to create GraphQL types, inputs, and interfaces without requiring separate wrapper classes.

Basic Usage

import strawberry
from pydantic import BaseModel

@strawberry.pydantic.type
class User(BaseModel):
    name: str
    age: int

@strawberry.pydantic.input
class CreateUserInput(BaseModel):
    name: str
    age: int

@strawberry.pydantic.interface
class Node(BaseModel):
    id: str

Features Implemented

Core Features

• ✅ @strawberry.pydantic.type - Convert Pydantic models to GraphQL types
• ✅ @strawberry.pydantic.input - Convert Pydantic models to GraphQL input types
• ✅ @strawberry.pydantic.interface - Convert Pydantic models to GraphQL interfaces
• ✅ Automatic field extraction from Pydantic models
• ✅ Pydantic field descriptions preserved in GraphQL schema
• ✅ Pydantic field aliases used as GraphQL field names
• ✅ Support for strawberry.Private to exclude fields from schema
• ✅ Support for strawberry.field() with Annotated for directives, permissions, deprecation
• ✅ Generic Pydantic model support
• ✅ Nested Pydantic types
• ✅ strawberry.pydantic.Error type for validation error handling
• ✅ Computed fields via include_computed=True

Pydantic v2 Features (130 Tests Passing)

• ✅ Functional Validators - BeforeValidator, AfterValidator, WrapValidator with Annotated types
• ✅ @model_validator Support - Cross-field validation with mode='before'|'after'|'wrap'
• ✅ Validation Context - Strawberry Info automatically passed to Pydantic validators
• ✅ model_config Settings - strict=True, extra='forbid', from_attributes=True all respected
• ✅ Strict Mode Per-Field - Field(strict=True) for individual field validation
• ✅ Separate Aliases - validation_alias and serialization_alias supported via by_name=True
• ✅ Discriminated Unions - Literal type support for type discriminators
• ✅ TypeAdapter - Use TypeAdapter in resolvers for scalar/list validation
• ✅ RootModel - Use RootModel for validated list/dict wrappers in resolvers

Migration from Experimental

# Before (experimental)
@strawberry.experimental.pydantic.type(model=UserModel, all_fields=True)
class User:
    pass

# After (first-class)
@strawberry.pydantic.type
class User(BaseModel):
    name: str
    age: int

Validation Context Example

Pydantic validators can access GraphQL context for permission-based validation:

from pydantic import field_validator, ValidationInfo

@strawberry.pydantic.input
class CreatePostInput(BaseModel):
    title: str

    @field_validator('title')
    @classmethod
    def check_permissions(cls, v: str, info: ValidationInfo) -> str:
        strawberry_info = info.context.get('info') if info.context else None
        if strawberry_info:
            user = strawberry_info.context.get('user')
            if user and not user.can_create_posts:
                raise ValueError('User cannot create posts')
        return v

Discriminated Union Example

from typing import Literal

@strawberry.pydantic.type
class Cat(BaseModel):
    pet_type: Literal["cat"]
    meow_volume: int

@strawberry.pydantic.type
class Dog(BaseModel):
    pet_type: Literal["dog"]
    bark_volume: int

@strawberry.type
class Query:
    @strawberry.field
    def pet(self) -> Cat | Dog:
        return Cat(pet_type="cat", meow_volume=10)

Test Results

• 130 Pydantic-specific tests - All passing ✅
• Full test suite (4675+ tests) - All passing ✅

🤖 Generated with Claude Code

[sourcery-ai[bot]]

Reviewer's Guide

This PR introduces first-class Pydantic support by adding a dedicated strawberry/pydantic module with type/input/interface decorators, overhauls the Pydantic integration documentation and migration guide, cleans up experimental code and unused flags, and restructures and extends the test suite to cover all new features.

File-Level Changes

Change	Details	Files
Add first-class Pydantic integration decorators	Create strawberry/pydantic/object_type.py with processing logic and decorators Implement _get_pydantic_fields and conversion utilities in strawberry/pydantic/fields.py Export new pydantic module in strawberry/pydantic/init.py Update strawberry/init.py to include pydantic in the public API	strawberry/pydantic/object_type.py strawberry/pydantic/fields.py strawberry/pydantic/__init__.py strawberry/__init__.py
Overhaul Pydantic documentation and remove experimental section	Expand docs/integrations/pydantic.md with installation, usage examples, decorator reference, advanced scenarios, and migration guide Remove outdated experimental examples and flags	docs/integrations/pydantic.md
Restructure and extend test suite for Pydantic integration	Move experimental tests into a new tests/pydantic directory and split them into focused modules Add comprehensive tests covering basic types, execution (queries/mutations/async), special features, nested types, and validation error handling	tests/pydantic/test_basic.py tests/pydantic/test_execution.py tests/pydantic/test_special_features.py tests/pydantic/test_queries_mutations.py tests/pydantic/test_nested_types.py
Cleanup unused experimental code and flags	Remove leftover experimental flags and references from strawberry.experimental.pydantic Delete deprecated _strawberry_input_type usage Tidy up compat module imports	strawberry/experimental/pydantic/_compat.py
Update CLAUDE.md and PLAN.md with new integration status	Detail completed implementation steps and migration path in PLAN.md Provide guidance and commands for the repository in CLAUDE.md	PLAN.md CLAUDE.md

Possibly linked issues

• #1: The PR implements first-class Pydantic integration, including new decorators and updated documentation, directly addressing Pydantic V2 support and migration.

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[codecov[bot]]

Codecov Report

:x: Patch coverage is 56.78818% with 1375 lines in your changes missing coverage. Please review. :white_check_mark: Project coverage is 91.27%. Comparing base (c03892c) to head (7067816).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3965      +/-   ##
==========================================
- Coverage   94.41%   91.27%   -3.14%     
==========================================
  Files         536      563      +27     
  Lines       35036    38186    +3150     
  Branches     1842     1913      +71     
==========================================
+ Hits        33079    34856    +1777     
- Misses       1659     3023    +1364     
- Partials      298      307       +9     

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[codspeed-hq[bot]]

CodSpeed Performance Report

Merging #3965 will not alter performance

_{Comparing feature/pydantic-first-class (7067816) with main (c03892c)}

Summary

✅ 28 untouched

[patrick91]

/pre-release

[botberry]

Pre-release

:wave:

Pre-release 0.279.0.dev.1754159379 [70130b4618633d5086793cc6e0b903c56ff1dc14] has been released on PyPi! :rocket: You can try it by doing:

poetry add strawberry-graphql==0.279.0.dev.1754159379

[patrick91]

/pre-release

[patrick91]

/pre-release