Map OpenAPI Discriminator mapping's values to their real value in enums by ilovelinux · Pull Request #3074 · koxudaxi/datamodel-code-generator

ilovelinux · 2026-04-05T19:01:02Z

Context

OpenAPI Discriminator mapping field is a key-value dictionary.
Both the keys and the values of the dictionary must be strings.
Despite they are strings, the mapping happens:
1. Converting any received value to string.
2. Comparing the converted value with the keys in the dictionary.

Ref: https://swagger.io/specification/#options-for-mapping-values-to-schemas

What's changed

Now mapping's keys are mapped to their real enum values, if available
Otherwise, old behavior kicks-in

Notes

Fix: OpenAPI integer discriminator with multiple enum values generates string Literals #3073

Summary by CodeRabbit

Bug Fixes
- Improved discriminator handling to correctly resolve and map multiple discriminator values, including numeric and float cases.
New Features
- Optional behavior to use enum values in discriminator resolution for more accurate mappings.
Tests
- Added regression tests covering integer/float discriminator mappings and the enum-value discriminator option.

coderabbitai · 2026-04-05T19:01:19Z

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 79f4bcd6-b6ae-4115-b54c-ba7b989e1063

📥 Commits

Reviewing files that changed from the base of the PR and between a07509f and 3a53bf3.

⛔ Files ignored due to path filters (1)

tests/data/openapi/discriminator_float_mapping.yaml is excluded by !tests/data/**/*.yaml and included by none

📒 Files selected for processing (4)

src/datamodel_code_generator/parser/base.py
tests/data/expected/main/openapi/discriminator/float_mapping.py
tests/data/expected/main/openapi/discriminator/integer_mapping_use_enum.py
tests/main/openapi/test_main_openapi.py

💤 Files with no reviewable changes (1)

tests/main/openapi/test_main_openapi.py

✅ Files skipped from review due to trivial changes (1)

tests/data/expected/main/openapi/discriminator/integer_mapping_use_enum.py

📝 Walkthrough

Walkthrough

Refactors Parser discriminator resolution to support enum-member default values vs enum field names based on use_enum_values_in_discriminator, adds base-class enum lookup, and updates/adds generated expectation files and tests for integer and float discriminator mappings.

Changes

Discriminator handling and test fixtures

Layer / File(s)	Summary
Parser: discriminator literal resolution & enum lookup `src/datamodel_code_generator/parser/base.py`	Branches `_create_discriminator_data_type` on `use_enum_values_in_discriminator`, adds `_get_enum_discriminator_literal`, introduces `get_enum_from_base()` to scan base models for `Enum`, and unifies `enum_source` selection and call sites.
Generated expected: float mapping models `tests/data/expected/main/openapi/discriminator/float_mapping.py`	Adds generated float-backed enums and models where discriminator Literals are stringified float values and a `Base` RootModel with `discriminator='kind'`.
Generated expected: integer mapping using enums `tests/data/expected/main/openapi/discriminator/integer_mapping_use_enum.py`	Adds generated IntEnum-backed discriminator models used when `--use-enum-values-in-discriminator` is enabled.
Tests: OpenAPI discriminator regression tests `tests/main/openapi/test_main_openapi.py`	Adds two regression tests asserting generation for integer-with-enum and float mapping discriminator YAML fixtures; tests skip on Black v19.

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~40 minutes

Possibly related PRs

koxudaxi/datamodel-code-generator#3070: Modifies discriminator handling in src/datamodel_code_generator/parser/base.py with related changes to enum-backed discriminator resolution.
koxudaxi/datamodel-code-generator#3078: Overlaps in discriminator validation/refinement in __apply_discriminator_type.
koxudaxi/datamodel-code-generator#3115: Changes discriminator-literal construction paths in __apply_discriminator_type.

Suggested labels

breaking-change-analyzed, breaking-change

Suggested reviewers

koxudaxi

Poem

🐰
I found the enums beneath the sod,
Rescued numbers miscast as odd,
Field names or defaults, now we pick,
Discriminators fixed—click by click. ✨

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 57.14% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: mapping OpenAPI discriminator values to their real enum values instead of treating them as strings.
Linked Issues check	✅ Passed	The PR successfully addresses issue `#3073` by implementing logic to map discriminator values to real enum types, enabling integer Literals (Literal[2, 3]) instead of string Literals (Literal['2', '3']).
Out of Scope Changes check	✅ Passed	All changes directly support the discriminator enum value mapping objective; no unrelated modifications were introduced beyond the stated scope.

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codspeed-hq · 2026-04-05T19:04:17Z

Merging this PR will improve performance by 14.76%

⚠️

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

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Different runtime environments detected

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Open the report in CodSpeed to investigate

⚡ 11 improved benchmarks
⏩ 98 skipped benchmarks¹

Performance Changes

	Mode	Benchmark	`BASE`	`HEAD`	Efficiency
⚡	WallTime	`test_perf_large_models_pydantic_v2`	3.8 s	3.3 s	+17.61%
⚡	WallTime	`test_perf_duplicate_names`	1,087.4 ms	941.6 ms	+15.48%
⚡	WallTime	`test_perf_complex_refs`	2.2 s	1.9 s	+15.19%
⚡	WallTime	`test_perf_deep_nested`	5.5 s	4.8 s	+15.8%
⚡	WallTime	`test_perf_multiple_files_input`	3.8 s	3.3 s	+15.51%
⚡	WallTime	`test_perf_openapi_large`	3 s	2.6 s	+14.98%
⚡	WallTime	`test_perf_all_options_enabled`	5.9 s	5.2 s	+14.19%
⚡	WallTime	`test_perf_kubernetes_style_pydantic_v2`	2.7 s	2.4 s	+12.74%
⚡	WallTime	`test_perf_graphql_style_pydantic_v2`	847.4 ms	736.9 ms	+15%
⚡	WallTime	`test_perf_stripe_style_pydantic_v2`	2 s	1.8 s	+10.86%
⚡	WallTime	`test_perf_aws_style_openapi_pydantic_v2`	2 s	1.7 s	+15.16%

Tip

Curious why this is faster? Comment @codspeedbot explain why this is faster on this PR, or directly use the CodSpeed MCP with your agent.

_{Comparing ilovelinux:fix/ilovelinux-3073-enum-literal-values (3a53bf3) with main (35f7156)}

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 · 2026-04-05T19:06:00Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (5b66f67) to head (3a53bf3).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##              main     #3074    +/-   ##
==========================================
  Coverage   100.00%   100.00%            
==========================================
  Files           89        92     +3     
  Lines        18650     19363   +713     
  Branches      2156      2206    +50     
==========================================
+ Hits         18650     19363   +713

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

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ilovelinux · 2026-04-05T19:14:17Z

This PR is draft because of the following tasks:

Check how this works with changes implemented in Fix non-string OpenAPI discriminator literals #3070 which solve a similar problem. There may be duplicate logic now.
CC: @koxudaxi
Review & evaluate potential corner-cases.

ilovelinux · 2026-05-20T11:00:14Z

Hi, right now I don't have enough time to complete this PR. Feel free to adopt it, otherwise I should have more free time in june to complete steps described in #3074 (comment) 🤞

@kkinugasa since it's related to your issue, would you mind testing this PR and give us a feedback? Does it fix your issue? Thanks!

koxudaxi · 2026-05-22T16:26:58Z

@coderabbitai review

coderabbitai · 2026-05-22T16:27:03Z

✅ Actions performed

Review triggered.

Note: CodeRabbit is an incremental review system and does not re-review already reviewed commits. This command is applicable only when automatic reviews are paused.

github-actions · 2026-05-22T17:12:18Z

Breaking Change Analysis

Result: No breaking changes detected

Reasoning: The PR's core behavioral change — resolving discriminator mapping keys to actual enum values — only affects the specific case of multiple discriminator mapping entries pointing to the same model with integer enum types. In that case, the old code generated string literals (e.g., Literal['2', '3']) which were non-functional and would fail Pydantic validation. The new code generates correct integer literals (Literal[2, 3]). Since the old output was already broken, no working user code is affected. For the common case (single mapping entry per model), the output is unchanged because get_discriminator_field_value() already resolved enum values before reaching _create_discriminator_data_type. The GenerationStore refactoring maintains backward compatibility: self.results is still a list (via subclass), and public function signatures (sort_data_models, sort_base_classes_for_mro) only add optional parameters with None defaults. Performance optimizations (_RenderedDataModelField caching, _has_field_statement, _get_unique_name) are behavior-preserving internal changes.

This analysis was performed by Claude Code Action

github-actions · 2026-05-25T03:26:24Z

🎉 Released in 0.58.0

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

ilovelinux added 2 commits April 5, 2026 20:45

Expand existing test

e23d1c6

Map discriminator mapping values with real enum values

a07509f

ilovelinux self-assigned this Apr 5, 2026

ilovelinux marked this pull request as draft April 5, 2026 19:14

ilovelinux changed the title ~~Draft: Map OpenAPI Discriminator mapping's values to their real value in enums~~ Map OpenAPI Discriminator mapping's values to their real value in enums Apr 5, 2026

koxudaxi and others added 2 commits April 23, 2026 02:25

Merge branch 'main' into fix/ilovelinux-3073-enum-literal-values

5d8f912

Merge branch 'main' into fix/ilovelinux-3073-enum-literal-values

462abc2

koxudaxi force-pushed the fix/ilovelinux-3073-enum-literal-values branch 4 times, most recently from c9e9459 to ee22e3d Compare May 22, 2026 15:05

Refine discriminator enum mapping

3a53bf3

koxudaxi force-pushed the fix/ilovelinux-3073-enum-literal-values branch from ee22e3d to 3a53bf3 Compare May 22, 2026 15:58

koxudaxi marked this pull request as ready for review May 22, 2026 16:25

koxudaxi merged commit 4999c2b into koxudaxi:main May 22, 2026
43 checks passed

github-actions Bot added the breaking-change-analyzed label May 22, 2026

coderabbitai Bot mentioned this pull request May 23, 2026

Fix msgspec enum discriminator tag #3170

Merged

github-actions Bot mentioned this pull request May 25, 2026

OpenAPI integer discriminator with multiple enum values generates string Literals #3073

Closed

coderabbitai Bot mentioned this pull request Jun 10, 2026

Fix enum member default resolution #3303

Merged

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ilovelinux commented Apr 5, 2026 • edited by coderabbitai Bot Loading Uh oh! There was an error while loading. Please reload this page.

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Merging this PR will improve performance by 14.76%

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ilovelinux commented Apr 5, 2026 •

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