datamodel-code-generator

Version updated for https://github.com/koxudaxi/datamodel-code-generator to version 0.52.0.

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Action Summary

The datamodel-code-generator is a tool designed to automate the generation of Python data models from various schema definitions, including OpenAPI, JSON Schema, GraphQL, and raw data formats like JSON, YAML, and CSV. It simplifies handling complex schemas (e.g., $ref, oneOf) and supports multiple output types such as Pydantic models, dataclasses, TypedDict, and msgspec, enabling type-safe, validated code for streamlined development. This action addresses the need for efficient model creation, reducing manual coding effort and ensuring compatibility with type checkers and IDEs.

Release notes

Breaking Changes

Code Generation Changes

  • Union fields with titles now wrapped in named models when --use-title-as-name is enabled - Previously, union-typed fields with a title were generated as inline union types (e.g., TypeA | TypeB | TypeC | None). Now they generate a separate wrapper model using the title name, and the field references this wrapper type (e.g., ProcessingStatusUnionTitle | None). This affects code that directly accesses union field values, as they now need to access the .root attribute (Pydantic v2) or .__root__ (Pydantic v1) of the wrapper model. (#2889) Before:
    class ProcessingTaskTitle(BaseModel):
    processing_status_union: (
        ProcessingStatusDetail | ExtendedProcessingTask | ProcessingStatusTitle | None
    ) = Field('COMPLETED', title='Processing Status Union Title')
    After:
    class ProcessingStatusUnionTitle(BaseModel):
    __root__: (
        ProcessingStatusDetail | ExtendedProcessingTask | ProcessingStatusTitle
    ) = Field(..., title='Processing Status Union Title')
class ProcessingTaskTitle(BaseModel):
    processing_status_union: ProcessingStatusUnionTitle | None = Field(
        default_factory=lambda: ProcessingStatusUnionTitle.parse_obj('COMPLETED'),
        title='Processing Status Union Title',
    )
  • Inline types with titles now generate named type aliases when --use-title-as-name is enabled - Arrays, dicts, enums-as-literals, and oneOf/anyOf unions that have a title in the schema now generate named type aliases or RootModel classes instead of being inlined. This improves readability but changes the generated type structure. For TypedDict output, generates type MyArrayName = list[str]. For Pydantic output, generates class MyArrayName(RootModel[list[str]]). (#2889)
  • Default value handling changed for wrapped union fields - Fields that previously had simple default values now use default_factory with a lambda that calls parse_obj() (Pydantic v1) or model_validate() (Pydantic v2) to construct the wrapper model. Code that introspects field defaults will see a factory function instead of a direct value. (#2889)
  • Different output for $ref with nullable: true - When a JSON Schema property has a $ref combined with only nullable: true (and optionally metadata like title/description), the generator now uses the referenced type directly with Optional annotation instead of creating a new merged model. For example, a schema with multiple properties referencing User with nullable: true will now generate user_a: User | None instead of creating separate UserA, UserB model classes. This is a bug fix that reduces redundant model generation, but existing code that depends on the previously generated class names will break. (#2890) Before:
    class UserA(BaseModel):
    name: str
class UserB(BaseModel):
    name: str
class Model(BaseModel):
    user_a: UserA | None = None
    user_b: UserB | None = None
    After:
    class User(BaseModel):
    name: str
class Model(BaseModel):
    user_a: User | None = None
    user_b: User | None = None
  • Type alias generation expanded for --use-title-as-name - When using --use-title-as-name, the generator now creates type aliases for additional cases: nested array items with titles, additionalProperties values with titles, oneOf/anyOf branches with titles, patternProperties, propertyNames, and primitive types with titles. Previously these were inlined; now they generate named type aliases. This is a bug fix per #2887, but changes generated output for schemas with titles on nested elements. (#2891)
  • Title no longer inherited in combined schemas - In anyOf/oneOf/allOf schemas, the parent schema’s title is now excluded when merging with child schemas. This prevents unintended title inheritance that could affect model naming when --use-title-as-name is enabled. (#2891)
  • allOf with single $ref no longer creates wrapper class - When a schema property uses allOf with only a single $ref and no additional properties, the generator now directly references the target type instead of creating an unnecessary wrapper class. This may affect code that depends on the previously generated wrapper class names or structure. For example, a property defined as allOf: [$ref: '#/components/schemas/ACHClass'] will now generate ach_class: ACHClass | None instead of creating an intermediate wrapper type. (#2902)

What’s Changed

Full Changelog: https://github.com/koxudaxi/datamodel-code-generator/compare/0.51.0...0.52.0