[Koudai Aono (koxudaxi)]

Summary by CodeRabbit

• New Features
  • Generated names, aliases, and identifiers now follow the Unicode rules of the selected target Python version, including for newer Unicode characters.
  • Formatting and code generation better support target-valid identifiers that the running Python interpreter does not recognize.
• Bug Fixes
  • Improved consistency in name validation, casing, normalization, and collision detection across generated models and API clients for different Python targets.

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Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-15T21:33:25.914404Z	2c818ca	PR opened

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📝 Walkthrough

The change adds target-specific Unicode tables and applies target-version-aware identifier, casing, normalization, naming, parsing, validation, and formatting behavior across code generation. It also adds interpreter table checks and Unicode-focused regression coverage.

Changes: Target-version Unicode behavior

Layer / File(s)	Summary
Unicode tables and runtime helpers scripts/build_target_python_tables.py, src/datamodel_code_generator/_target_unicode.py, src/datamodel_code_generator/_target_unicode_data.py	Adds generated Unicode data for Python 3.10–3.15 and helpers for target-aware identifiers, casing, normalization, numeric checks, word matching, and host-identifier translation.
Target-aware naming and validation src/datamodel_code_generator/_alias_generators.py, src/datamodel_code_generator/_target_naming.py, src/datamodel_code_generator/reference.py, src/datamodel_code_generator/_api_generation.py, src/datamodel_code_generator/_target_config.py, src/datamodel_code_generator/util.py	Propagates the configured Python version through aliases, names, module paths, explicit-name validation, case folding, normalization, and collision checks.
Parser and model integration src/datamodel_code_generator/parser/*, src/datamodel_code_generator/model/*, tests/main/jsonschema/*, tests/data/expected/main/jsonschema/*	Uses target-version rules during parsing, model resolution, field validation, alias generation, module grouping, and generated output. Adds Unicode identifier, alias, enum, dataclass, Pydantic, TypedDict, and module-name coverage.
Client and FastAPI integration src/datamodel_code_generator/_client/*, src/datamodel_code_generator/_fastapi/*, tests/api_generation/test_client_generation.py, tests/data/expected/main/generation_platform/*	Passes target versions through client and FastAPI validation, planning, naming, collision checks, helper generation, rendering, and output fixtures.
Formatter and host parsing src/datamodel_code_generator/_builtin_formatter.py, src/datamodel_code_generator/model/base.py, src/datamodel_code_generator/model/output.py, tests/test_format.py	Supports target identifiers that the host parser cannot read by lending placeholder characters, restoring names in AST operations, and preserving target-aware import ordering and formatted output.

Priority: ➖ Normal

Estimated code review effort: 5 (Critical) | ~90 minutes

Change: Bug fix

Sequence Diagram(s)

sequenceDiagram
  participant Generator
  participant TargetUnicode
  participant Parser
  participant Formatter
  participant GeneratedCode
  Generator->>TargetUnicode: resolve rules for target Python version
  TargetUnicode->>Parser: provide identifier and naming behavior
  Parser->>Formatter: pass target names and source
  Formatter->>Formatter: lend and restore unsupported identifiers
  Formatter->>GeneratedCode: emit target-compatible code

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Merge Risk: 🔵 Low · up to 2c818

This change makes generated names follow the target Python version's Unicode rules. One narrow gap remains: with model reuse enabled, models that reference types whose names begin with non-ASCII characters may not be merged. The generated code is still valid, so this does not block merging.

Pre-merge checks: 4 · 1

Failed checks: 1 inconclusive

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 70.45% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 247 functions across 45 files. (2 skipped…	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks: 4 passed

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly and concisely describes the main change: generated names now follow the target Python version's Unicode rules.
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

Full details: Docstring Coverage

Explanation

Docstring coverage is 70.45% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 247 functions across 45 files. (2 skipped: 2 too large.)

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[github-actions]

📚 Docs Preview: https://pr-4790.datamodel-code-generator.pages.dev

[codspeed]

Merging this PR will improve performance by 70.94%

⚠️ 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.

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 49 improved benchmarks
⏩ 98 skipped benchmarks¹

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
⚡	test_perf_unique_items_nested_model_validation	3.3 ms	1.6 ms	×2.1
⚡	test_perf_unique_items_runtime_scalar_validation	3.1 ms	1.5 ms	×2
⚡	test_perf_empty_pydantic_v2_field_render_plans	12.8 ms	6.6 ms	+94.13%
⚡	test_perf_pydantic_field_name_resolution	1,805.2 µs	969 µs	+86.29%
⚡	test_perf_duplicate_names	830 ms	446.6 ms	+85.83%
⚡	test_perf_simple_pydantic_v2_field_construction	10.9 ms	5.9 ms	+84.19%
⚡	test_perf_complex_refs	1,602.2 ms	882.2 ms	+81.61%
⚡	test_perf_extreme_large_schema	12.5 s	6.9 s	+81.61%
⚡	test_perf_pattern_properties_adapter_reuse	3.9 ms	2.2 ms	+81.4%
⚡	test_perf_local_reference_file_resolution	58.5 ms	32.4 ms	+80.7%
⚡	test_perf_deep_nested	4.2 s	2.3 s	+80.29%
⚡	test_perf_scalar_root_collapsed_builtin	85 ms	47.2 ms	+79.88%
⚡	test_perf_client_calls[async]	35.2 ms	19.6 ms	+79.44%
⚡	test_perf_unique_items_permuted_object_validation	71.7 ms	40.1 ms	+78.87%
⚡	test_perf_target_render[client-small]	27.1 ms	15.2 ms	+78.21%
⚡	test_perf_openapi_large	2.4 s	1.4 s	+76.83%
⚡	test_perf_load_pyproject_config[config-multiple]	304.1 µs	173.2 µs	+75.6%
⚡	test_perf_unique_items_runtime_nested_object_validation	7.2 ms	4.1 ms	+75.5%
⚡	test_perf_all_options_enabled	4.5 s	2.5 s	+75.48%
⚡	test_perf_load_pyproject_config[config-None]	291.7 µs	166.2 µs	+75.46%
...	...	...	...	...

ℹ️ Only the first 20 benchmarks are displayed. Go to the app to view all benchmarks.

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---

_{Comparing target-unicode-names (5f5a471) with main (fa5c481)}

Footnotes

1. 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]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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Actionable comments posted: 1

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• 🪄 Fix comments: Fix CodeRabbit comments on this PR

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Inline comments:
Review comments at @src/datamodel_code_generator/parser/base.py:
- Line 165: Update the identifier-start matching in the regex used by
_model_shape so it recognizes non-ASCII starts such as é, using target-aware
identifier rules alongside the existing \w handling. Preserve the current
masking and capture behavior for ASCII names.

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• Configuration used: Repository: datamodel-code-generator/datamodel-code-generator/.coderabbit.yaml
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📥 Commits

Reviewing files that changed from the base of the PR and between fa5c481 and 2c818ca.

⛔ Files ignored due to path filters: 12

• tests/data/expected/architecture_boundaries/cli.txt is excluded by !tests/data/**/*.txt and included by none
• tests/data/expected/builtin_formatter/target_identifiers.txt is excluded by !tests/data/**/*.txt and included by none
• tests/data/expected/main/generation_platform/client/packages/typeddict-target-keys/typing_TypedDict/client/_generated/model_bindings.py is excluded by !**/_generated/** and included by tests/**/*.py, tests/data/expected/**/*.py
• tests/data/expected/main/generation_platform/client/typeddict-target-keys.txt is excluded by !tests/data/**/*.txt and included by none
• tests/data/expected/main/jsonschema/identifier_module_target_315.txt is excluded by !tests/data/**/*.txt and included by none
• tests/data/expected/target_python_tables/check_interpreter.txt is excluded by !tests/data/**/*.txt and included by none
• tests/data/generation_platform/client/cases.json is excluded by !tests/data/**/*.json and included by none
• tests/data/generation_platform/client/typeddict-target-keys.yaml is excluded by !tests/data/**/*.yaml and included by none
• tests/data/jsonschema/identifier_case_target.json is excluded by !tests/data/**/*.json and included by none
• tests/data/jsonschema/identifier_module_target.json is excluded by !tests/data/**/*.json and included by none
• tests/data/jsonschema/identifier_type_alias_target.json is excluded by !tests/data/**/*.json and included by none
• tests/data/jsonschema/identifier_unicode_target.json is excluded by !tests/data/**/*.json and included by none

📒 Files selected for processing: 47

• scripts/build_target_python_tables.py
• src/datamodel_code_generator/_alias_generators.py
• src/datamodel_code_generator/_api_generation.py
• src/datamodel_code_generator/_builtin_formatter.py
• src/datamodel_code_generator/_client/config.py
• src/datamodel_code_generator/_client/fields.py
• src/datamodel_code_generator/_client/naming.py
• src/datamodel_code_generator/_client/plan.py
• src/datamodel_code_generator/_client/protocol_plan.py
• src/datamodel_code_generator/_client/protocols.py
• src/datamodel_code_generator/_client/render.py
• src/datamodel_code_generator/_client/webhooks.py
• src/datamodel_code_generator/_fastapi/config.py
• src/datamodel_code_generator/_fastapi/naming.py
• src/datamodel_code_generator/_fastapi/plan.py
• src/datamodel_code_generator/_fastapi/render.py
• src/datamodel_code_generator/_target_binding.py
• src/datamodel_code_generator/_target_config.py
• src/datamodel_code_generator/_target_naming.py
• src/datamodel_code_generator/_target_unicode.py
• src/datamodel_code_generator/_target_unicode_data.py
• src/datamodel_code_generator/model/base.py
• src/datamodel_code_generator/model/msgspec.py
• src/datamodel_code_generator/model/output.py
• src/datamodel_code_generator/model/pydantic_v2/base_model.py
• src/datamodel_code_generator/model/pydantic_v2/dataclass.py
• src/datamodel_code_generator/model/typed_dict.py
• src/datamodel_code_generator/parser/base.py
• src/datamodel_code_generator/parser/jsonschema.py
• src/datamodel_code_generator/parser/openapi.py
• src/datamodel_code_generator/parser/openapi_scope.py
• src/datamodel_code_generator/reference.py
• src/datamodel_code_generator/util.py
• tests/api_generation/test_client_generation.py
• tests/data/expected/main/generation_platform/client/packages/typeddict-target-keys/typing_TypedDict/models.py
• tests/data/expected/main/jsonschema/identifier_case_target_313.py
• tests/data/expected/main/jsonschema/identifier_case_target_314.py
• tests/data/expected/main/jsonschema/identifier_type_alias_target_312.py
• tests/data/expected/main/jsonschema/identifier_unicode_target_dataclass_312.py
• tests/data/expected/main/jsonschema/identifier_unicode_target_dataclass_313.py
• tests/data/expected/main/jsonschema/identifier_unicode_target_dataclass_314.py
• tests/data/expected/main/jsonschema/identifier_unicode_target_dataclass_315.py
• tests/data/expected/main/jsonschema/identifier_unicode_target_pydantic_315.py
• tests/data/expected/main/jsonschema/identifier_unicode_target_typed_dict_314.py
• tests/main/jsonschema/test_main_jsonschema.py
• tests/test_build_target_python_tables_script.py
• tests/test_format.py

Included review availability: This review used your included allowance. Your plan provides up to 8 included reviews per hour; 0 remain after this review.

[github-actions]

Breaking Change Analysis

Result: Breaking changes detected

Reasoning: I read the whole diff. The PR adds per-target Unicode tables and a _target_unicode module, and routes identifier checks, word and numeric matching, case mapping, casefolding and NFKC normalization through --target-python-version instead of the running interpreter. For ASCII names nothing changes, and no existing expected outputs change; only new expected files are added. For non-ASCII names, the generated field, enum member, class and module names can now differ from before when the running interpreter's Unicode version is not the target's. The new tests show this: 京都 becomes field_京都 only for 3.13 or later targets, and ɤ is uppercased only for 3.14 or later targets. Previously the running interpreter decided both, so existing users can see renamed fields or members. Explicit names are now validated against the target's identifier rules too. This covers CLI class name options, the model name map, explicit aliases and client or FastAPI config names, so a name the running interpreter accepts can now be rejected for an older target. The signature changes are additive optional parameters on public helpers like snake_to_upper_camel, camel_to_snake and validate_name. Required parameters were added only in private modules. The removed _NON_IDENTIFIER_PATTERN, _FIELD_NAME_RESOLVER and the classmethod form of _get_model_name are all private. No CLI options, templates or supported Python versions change.

Content for Release Notes

Code Generation Changes

• Non-ASCII identifiers now follow the target Python version's Unicode rules - Field names, class names, enum member names, module names, alias generator output (to_camel, to_pascal, to_snake), OpenAPI operation model names and the builtin formatter's import ordering are now worked out from Unicode tables for --target-python-version. Those tables cover identifier characters, \w, numeric characters, case mappings and NFKC normalization. Before, these names came from the str, re and unicodedata behaviour of the interpreter running datamodel-codegen. ASCII names are unaffected, but output for non-ASCII schema names can change when the running interpreter's Unicode version differs from the target's. For example, a property 京都 (U+4EAC is numeric from Python 3.13) used to become field_京都 when generated on Python 3.13 or later. It is now emitted as 京都 for targets up to 3.12, and the reverse happens when generating on an older Python for a 3.13 or later target. Likewise, --capitalise-enum-members no longer turns ɤ into Ɤ for targets older than 3.14, even when running on Python 3.14. Regenerate and review models whose names contain non-ASCII characters, because renamed fields and members break code that refers to them (Follow the target Python's Unicode version for generated names #4790)

Error Handling Changes

• Explicit names are now checked as identifiers of the target Python version - This applies to --class-name, --class-name-prefix, --class-name-suffix, --special-field-name-prefix, --model-name-map values and explicit field aliases. It also applies to client and FastAPI generation settings such as package, model_package, resource namespaces, operation, parameter and router names, and protocol helper names. These are now checked against the identifier rules of --target-python-version, not the running interpreter, so a name that uses characters only a newer Python accepts is now rejected (for example with E_CONFIG_VALUE or an invalid identifier error) when targeting an older Python, even if the running interpreter accepts it (Follow the target Python's Unicode version for generated names #4790)

---

This analysis was produced by the release draft workflow

[github-actions]

🎉 Released in 0.85.0

This PR is now available in the latest release. See the release notes for details.