Fix missing | None for nullable enum literals in TypedDict

[koxudaxi]

Fixes: #2986

Summary by CodeRabbit

• Bug Fixes

  • Generated models now represent nullable enums correctly: None is included in enum literals where present and optional/nullability flags propagate to fields and model types.

• Tests

  • Added a test covering nullable enum literals in TypedDict generation and updated expected model outputs to reflect nullable enum handling.

[coderabbitai]

Note

Reviews paused

It looks like this branch is under active development. To avoid overwhelming you with review comments due to an influx of new commits, CodeRabbit has automatically paused this review. You can configure this behavior by changing the reviews.auto_review.auto_pause_after_reviewed_commits setting.

Use the following commands to manage reviews:

• @coderabbitai resume to resume automatic reviews.
• @coderabbitai review to trigger a single review.

Use the checkboxes below for quick actions:

• ▶️ Resume reviews
• 🔍 Trigger review

📝 Walkthrough

Walkthrough

parse_enum_as_literal now excludes literal None from Literal members and marks the resulting DataType as optional when None/null is present in the JSON Schema enum, causing generated Literal types to be emitted as Literal[...] | None for nullable enums; tests and expected outputs updated.

Changes

Cohort / File(s)	Summary
Parser Logic src/datamodel_code_generator/parser/jsonschema.py	Modify parse_enum_as_literal to build Literal values from enum entries excluding None/null and set DataType.is_optional = True when None/null is present, so nullable enums become `Literal[...]
TypedDict JSON Schema tests & expected output tests/data/expected/main/jsonschema/typed_dict_nullable_enum_literal.py, tests/main/jsonschema/test_main_jsonschema.py	Add expected TypedDict model and test asserting nullable enums are emitted as `Literal[...]
OpenAPI enum expected outputs tests/data/expected/main/openapi/enum_models/all.py, tests/data/expected/main/openapi/enum_models/as_literal.py	Update expected OpenAPI-generated enum model roots to include `

Sequence Diagram(s)

(skip — changes are parser-only and do not introduce multi-component sequential flows)

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

• feat: Add --enum-field-as-literal none option and respect user settings for TypedDict #2691: Modifies JSON Schema enum-to-Literal handling; closely related parser-area change.
• Nullable required fields should not have default value #2520: Changes how enum types are marked optional and influences template behavior for emitting None.
• Fix crash when parsing enum containing only null value #2674: Adjusts enum parsing for nullable/null enum cases in the same parser module.

Suggested labels

breaking-change-analyzed

Suggested reviewers

• ilovelinux

Poem

🐰 A hop, a nibble, a tiny cheer,
Enums learned to hold a None so dear.
Literals stretch and TypeAlias grows wide,
TypedDicts now let nullable values inside. 🥕

🚥 Pre-merge checks | ✅ 6

✅ Passed checks (6 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'Fix missing | None for nullable enum literals in TypedDict' is concise, specific, and directly reflects the main change: fixing nullable enum literals in TypedDict output.
Linked Issues check	✅ Passed	The PR successfully addresses all coding requirements from issue #2986: nullable enum TypeAliases include '| None', required inline enum fields are nullable, and optional inline enum fields within NotRequired are nullable.
Out of Scope Changes check	✅ Passed	All changes are directly related to fixing nullable enum literals in TypedDict: the core parser fix, the new test file with expected output, the test case, and updates to existing enum test fixtures.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
Merge Conflict Detection	✅ Passed	✅ No merge conflicts detected when merging into main

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch fix/nullable-enum-literal-typed-dict

---

No actionable comments were generated in the recent review. 🎉

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[github-actions]

📚 Docs Preview: https://pr-2991.datamodel-code-generator.pages.dev

[coderabbitai]

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@src/datamodel_code_generator/parser/jsonschema.py`:
- Around line 3529-3534: In parse_enum_as_literal, guard against enums that are
all-None by first building literals = [i for i in obj.enum if i is not None] and
is_optional = None in obj.enum, then if literals is empty and is_optional is
True return a None-only DataType (i.e., construct and return self.data_type that
represents a None-only enum — for example with empty literals and
is_optional=True) instead of returning a potentially invalid empty Literal;
otherwise return the normal self.data_type(literals=literals,
is_optional=is_optional).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (0f1bc0f) to head (1793c21).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main     #2991   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           94        94           
  Lines        18065     18068    +3     
  Branches      2090      2090           
=========================================
+ Hits         18065     18068    +3     

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

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[github-actions]

Breaking Change Analysis

Result: No breaking changes detected

Reasoning: This PR is a bug fix that corrects generated code to include | None for enum types that contain null in their values. Previously, when a schema defined an enum like enum: ["red", "amber", "green", null, 42], the generated code incorrectly produced Literal['red', 'amber', 'green', 42] (dropping the nullability). Now it correctly produces Literal['red', 'amber', 'green', 42] | None. This is not a breaking change because: (1) the old output was incorrect - it didn't match the schema semantics, (2) the new output is the correct representation of a nullable enum, and (3) existing code that relied on the old behavior was technically incorrect since the schema allows null values. Bug fixes that correct generated output to match schema definitions are not considered breaking changes.

---

This analysis was performed by Claude Code Action

[github-actions]

🎉 Released in 0.54.0

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