Optimize deepcopy for empty lists by koxudaxi · Pull Request #2862 · koxudaxi/datamodel-code-generator

koxudaxi · 2025-12-30T08:17:42Z

Summary by CodeRabbit

Bug Fixes
- Improved data model field initialization in JSON Schema and OpenAPI parsers and core type definitions to prevent unintended state sharing between model instances when processing multiple schemas and API specifications, enhancing reliability and ensuring consistent behavior throughout the code generation workflow.

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coderabbitai · 2025-12-30T08:17:49Z

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📥 Commits

Reviewing files that changed from the base of the PR and between 223a237 and 9a2307a.

📒 Files selected for processing (3)

src/datamodel_code_generator/parser/jsonschema.py
src/datamodel_code_generator/parser/openapi.py
src/datamodel_code_generator/types.py

📝 Walkthrough

Walkthrough

Mutable default values are replaced with Field(default_factory=...) across three modules—JsonSchema parser, OpenAPI parser, and core types—to prevent shared-state issues where instances would unintentionally share the same list or dict objects.

Changes

Cohort / File(s)	Change Summary
JsonSchema Parser `src/datamodel_code_generator/parser/jsonschema.py`	Five fields converted: `oneOf`, `anyOf`, `allOf`, `enum`, and `required` now use `Field(default_factory=list)` instead of mutable default lists.
OpenAPI Parser `src/datamodel_code_generator/parser/openapi.py`	Thirteen field declarations across five objects converted: `ParameterObject.content`, `HeaderObject.content`, `RequestBodyObject.content`, `ResponseObject.headers`, `ResponseObject.content`, `Operation.tags`, `Operation.parameters`, `Operation.responses`, and multiple `ComponentsObject` fields now use `Field(default_factory=dict)` or `Field(default_factory=list)`.
Core Types `src/datamodel_code_generator/types.py`	Four `DataType` fields converted: `data_types`, `literals`, `enum_member_literals`, and `children` now use `Field(default_factory=list)` instead of mutable default lists.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~12 minutes

Poem

🐰 Hopping through defaults, a fix most fine,
Factory-made lists—no sharing of mine!
Each instance now pristine, independent, free,
No mutable mishaps in Pydantic's spree! 🌿✨

Pre-merge checks and finishing touches

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately reflects the main change: converting mutable default lists to Field(default_factory=list) across multiple files to optimize deepcopy performance for empty containers.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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github-actions · 2025-12-30T08:18:24Z

📚 Docs Preview: https://pr-2862.datamodel-code-generator.pages.dev

codspeed-hq · 2025-12-30T08:20:49Z

CodSpeed Performance Report

Merging #2862 will not alter performance

_{Comparing perf/optimize-empty-list-deepcopy (9a2307a) with main (6dd1dbe)}

⚠️

Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

Summary

✅ 11 untouched
⏩ 98 skipped¹

98 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

codecov · 2025-12-30T08:22:20Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.38%. Comparing base (6dd1dbe) to head (9a2307a).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2862   +/-   ##
=======================================
  Coverage   99.38%   99.38%           
=======================================
  Files          91       91           
  Lines       15555    15555           
  Branches     1827     1827           
=======================================
  Hits        15460    15460           
  Misses         50       50           
  Partials       45       45

Flag	Coverage Δ
unittests	`99.38% <100.00%> (ø)`

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coderabbitai

Actionable comments posted: 0

🧹 Nitpick comments (3)

src/datamodel_code_generator/parser/jsonschema.py (1)

22-24: JsonSchemaObject list defaults via Field(default_factory=...) look correct and improve safety

Switching oneOf, anyOf, allOf, enum, and required to Field(default_factory=list) is consistent with how these fields are used:

Call sites treat oneOf/anyOf/allOf/enum as lists or via truthiness, so always having a list (possibly empty) matches expectations.

required is already normalized by validate_required() to [] for None/weird inputs, and other code only checks it via truthiness or iterates it; having an empty list instead of None preserves behavior. The obj.required is None branch in parse_object_fields() becomes dead but harmless.

Low‑priority nits:

You could simplify requires in parse_object_fields() since required is now always a list.

Ruff reports unused noqa codes on these lines (e.g., N815, UP045 not enabled); if you want a clean lint run, consider dropping or narrowing them.

Also applies to: 354-357, 361-361

src/datamodel_code_generator/types.py (1)

29-32: DataType list defaults via Field(default_factory=list) are consistent with existing usage

Using Field(default_factory=list) for data_types, literals, enum_member_literals, and children aligns with how these fields are treated everywhere:

They are always consumed as lists (iteration, len(...), truthiness), so an always‑list default is appropriate.

It avoids any chance of shared mutable defaults across instances, while remaining compatible with __deepcopy__, __init__’s parent propagation, and the dynamically created ContextDataType via create_model.

Minor lint note:

Ruff flags some noqa codes on these lines (e.g., UP007, UP045) as unused; you can drop or narrow them later if you want a quieter lint run.

Also applies to: 431-431, 445-447, 452-452

src/datamodel_code_generator/parser/openapi.py (1)

18-18: OpenAPI model container defaults via Field(default_factory=...) are safe and match call‑site expectations

The new defaults for content, headers, tags, parameters, responses, and all ComponentsObject dicts look correct:

Callers (parse_all_parameters, parse_request_body, parse_responses, parse_operation) already treat these attributes as dictionaries/lists and never distinguish between None and “no entries”.

Using Field(default_factory=dict/list) removes any possibility of shared mutable state between model instances and keeps semantics the same for “missing vs. empty” in the OpenAPI documents.

Optional lint cleanup:

Ruff reports several adjacent # noqa directives (e.g., UP007, UP045, N815) as unused; you can safely trim or narrow them in a follow‑up if you want cleaner lint output.

Also applies to: 124-137, 143-143, 151-152, 158-165, 171-175

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📥 Commits

Reviewing files that changed from the base of the PR and between 83776ca and 223a237.

📒 Files selected for processing (3)

src/datamodel_code_generator/parser/jsonschema.py
src/datamodel_code_generator/parser/openapi.py
src/datamodel_code_generator/types.py

🧰 Additional context used

🧬 Code graph analysis (2)

src/datamodel_code_generator/parser/jsonschema.py (1)

tests/data/expected/parser/openapi/openapi_parser_parse_modular/bar.py (1)

Field (6-7)

src/datamodel_code_generator/types.py (1)

src/datamodel_code_generator/model/base.py (1)

DataModelFieldBase (151-469)

🪛 Ruff (0.14.10)

src/datamodel_code_generator/parser/jsonschema.py

354-354: Unused noqa directive (non-enabled: N815)