bugfix/preserve-casing-via-config

[iOSonntag]

Add preserve_schema_casing option to honour spec-author casing

Fixes #458

Summary

Adds an opt-in config flag preserve_schema_casing (default false) that
projects schema and enum names into the target language by stripping
separator characters while preserving the casing of every other character.
This lets generators emit XMLHttpRequest, kUserStatus, iOSDevice, and
URL verbatim instead of normalising them to XmlHttpRequest,
KUserStatus, IOsDevice, and Url.

Currently the only way around the normalisation is replacement_rules,
which doesn't work for this case because the rules run after the
PascalCase normalisation has already destroyed the casing information.

Behaviour

When preserve_schema_casing: true:

Schema name	Output	Note
kUserStatus	kUserStatus	lowercase prefix preserved
XMLHttpRequest	XMLHttpRequest	internal acronym preserved
iOSDevice	iOSDevice	mixed-case prefix preserved
URL	URL	all-caps preserved
HTTPSConnection	HTTPSConnection
UserStatus	UserStatus	unchanged
user_status	userstatus	separator stripped, rest verbatim
My-Class	MyClass	separator stripped
XML Http Request	XMLHttpRequest	spaces stripped, casing kept

The rule is uniform: strip separator characters, preserve the casing of
every other character. No special-casing, no carve-outs.

Default (false) is the existing PascalCase normalisation — unchanged.

Implementation

The change adds one new String extension and threads a single decision
point through the existing flow:

• String.toPreservedCase (new): one small extension getter in
  lib/src/parser/model/normalized_identifier.dart that strips separator
  characters and mirrors toPascal's Private prefix handling. Uses the
  same _separatorPattern already defined at the top of the file.

• OpenApiCorrector: a one-line conditional swaps correctType.toPascal
  for correctType.toPreservedCase when the flag is on. This is where
  schema keys get rewritten in the JSON/YAML content before the parser
  reads it.

• OpenApiParser: a small private helper
  String _schemaIdentifier(String input) picks between .toPreservedCase
  and .toPascal based on the flag. Wired into 6 call sites that handle
  user-controlled schema names (enum class name, inline schema type, $ref
  resolutions). The corrector's YAML rewrite is skipped when the preserved
  form equals the input, so the parser still has to honour the flag for
  those cases. Synthesised wrapper names ('X Union'.toPascal,
  '$name $additionalName'.toPascal) are intentionally left
  unconditional — they should always be PascalCase.

• Config wiring: SWPConfig.preserveSchemaCasing field + YAML key
  preserve_schema_casing + toParserConfig plumbing +
  ParserConfig.preserveSchemaCasing.

NormalizedIdentifier itself is untouched — no new fields, no new
getters on the class. The only addition is one String extension at the
bottom of the same file.

Why the DTO templates changed (and why it doesn't actually matter)

Five templates had final className = dataClass.name.toPascal;. With the
flag on, that would convert XMLHttpRequest back to XmlHttpRequest and
defeat the preservation. The fix changes them to
final className = dataClass.name; — dropping the call entirely.

This works because the parser already stores name in its final
target-language form for both modes:

• Component class names are assigned from post-corrector keys (PascalCase
  in legacy mode, preserved-case in flag-on mode).
• Enum class names go through _schemaIdentifier(uniqueName).
• Synthesised wrapper names are pascalised at construction.

In other words: dataClass.name is already a final identifier by the
time it reaches a template, so .toPascal was always redundant. The
codebase already implicitly assumes this — see
dart_json_serializable_dto_template.dart:515 and
dart_dart_mappable_dto_template.dart:652, which
compare variantName == dataClass.name without any transformation.

Removing the redundant .toPascal from the templates is a no-op in
legacy mode (PascalCase in → PascalCase out) and necessary in flag-on
mode (preserved-case in → preserved-case out).

UniversalComponentClass.import is not touched. It still returns
name.toPascal, exactly as upstream. The only consumer adds the result
to an imports set that downstream templates snake-case via .toSnake
for filename derivation — and .toSnake('XMLHttpRequest') ==
.toSnake('XmlHttpRequest'), so the existing .toPascal is harmless
even in flag-on mode.

Tests

No existing tests were modified — none of the changes affect behaviour
when the flag is off, and all 421 pre-existing tests pass unchanged.

New tests added:

• test/src/parser/model/normalized_identifier_test.dart — a new
  String.toPreservedCase group covering: no-separator preservation,
  separator stripping, Private prefix handling, inner-underscore
  stripping after a private prefix, idempotency, and empty input.
• test/config/swp_config_test.dart — a new Preserve Schema Casing Configuration group following the same shape as the existing
  Include If Null Configuration group (default value, YAML parsing
  true/false, root config inheritance, override, toParserConfig
  wiring). Plus three assertions added to the existing
  constructor/YAML-loading tests to cover the new field.
• test/e2e/tests/preserve_schema_casing/ — a new e2e fixture
  whose OpenAPI spec exercises kUserStatus, XMLHttpRequest,
  iOSDevice, and URL as top-level schemas, all referenced as fields
  of a User model. The expected generated files prove that the class
  names, type references, and (snake_case) filenames all line up.
• test/e2e/e2e_test.dart — one new test entry registering the
  fixture above.

Total suite: 422 passing.

Files touched

 swagger_parser/lib/src/config/swp_config.dart                          | +32
 swagger_parser/lib/src/generator/templates/dart_dart_mappable_dto_template.dart | ±1
 swagger_parser/lib/src/generator/templates/dart_enum_dto_template.dart          | ±2
 swagger_parser/lib/src/generator/templates/dart_freezed_dto_template.dart       | ±1
 swagger_parser/lib/src/generator/templates/dart_json_serializable_dto_template.dart | ±1
 swagger_parser/lib/src/generator/templates/dart_typedef_template.dart           | ±1
 swagger_parser/lib/src/parser/config/parser_config.dart                | +14
 swagger_parser/lib/src/parser/corrector/open_api_corrector.dart        | ±4
 swagger_parser/lib/src/parser/model/normalized_identifier.dart         | +27
 swagger_parser/lib/src/parser/parser/open_api_parser.dart              | ±20
 swagger_parser/test/config/swp_config_test.dart                        | +78
 swagger_parser/test/e2e/e2e_test.dart                                  | +14
 swagger_parser/test/src/parser/model/normalized_identifier_test.dart   | +49
 swagger_parser/test/e2e/tests/preserve_schema_casing/                  | new fixture

dart format . clean. dart analyze reports no issues. dart test
passes 422/422.

[Copilot]

Pull request overview

Adds an opt-in preserve_schema_casing / preserveSchemaCasing configuration to stop forced PascalCase normalization of schema/enum identifiers, allowing generated identifiers to retain spec-author casing while stripping separator characters.

Changes:

• Introduces String.toPreservedCase and threads a single decision point through the corrector + parser to preserve casing when enabled.
• Updates Dart generator templates to stop re-PascalCasing already-normalized dataClass.name / enumClass.name.
• Adds unit/config tests and a new e2e fixture to validate preserved casing for kUserStatus, XMLHttpRequest, iOSDevice, and URL.

Reviewed changes

Copilot reviewed 24 out of 24 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
swagger_parser/lib/src/config/swp_config.dart	Adds preserveSchemaCasing option, YAML parsing/wiring to ParserConfig, and documents behavior.
swagger_parser/lib/src/parser/config/parser_config.dart	Adds preserveSchemaCasing flag to parser configuration.
swagger_parser/lib/src/parser/model/normalized_identifier.dart	Adds String.toPreservedCase implementation.
swagger_parser/lib/src/parser/corrector/open_api_corrector.dart	Uses preserved casing vs PascalCase when rewriting schema keys/refs based on config.
swagger_parser/lib/src/parser/parser/open_api_parser.dart	Introduces _schemaIdentifier() helper and applies it to schema-derived identifiers and $ref resolutions.
swagger_parser/lib/src/generator/templates/dart_typedef_template.dart	Stops re-applying .toPascal to dataClass.name for typedef generation.
swagger_parser/lib/src/generator/templates/dart_json_serializable_dto_template.dart	Stops re-applying .toPascal to dataClass.name for JSON-serializable DTOs.
swagger_parser/lib/src/generator/templates/dart_freezed_dto_template.dart	Stops re-applying .toPascal to dataClass.name for Freezed DTOs.
swagger_parser/lib/src/generator/templates/dart_enum_dto_template.dart	Stops re-applying .toPascal to enumClass.name in enum templates.
swagger_parser/lib/src/generator/templates/dart_dart_mappable_dto_template.dart	Stops re-applying .toPascal to dataClass.name for dart_mappable DTOs.
swagger_parser/test/config/swp_config_test.dart	Adds coverage for default/YAML/root override behavior + wiring into ParserConfig.
swagger_parser/test/src/parser/model/normalized_identifier_test.dart	Adds unit tests for String.toPreservedCase.
swagger_parser/test/e2e/e2e_test.dart	Registers a new e2e scenario enabling preserveSchemaCasing.
swagger_parser/test/e2e/tests/preserve_schema_casing/openapi.yaml	New fixture OpenAPI spec exercising mixed-case schema names.
swagger_parser/test/e2e/tests/preserve_schema_casing/expected_files/rest_client.dart	Expected generated output for the new e2e fixture.
swagger_parser/test/e2e/tests/preserve_schema_casing/expected_files/export.dart	Expected barrel export output for the new e2e fixture.
swagger_parser/test/e2e/tests/preserve_schema_casing/expected_files/clients/fallback_client.dart	Expected client output for the new e2e fixture.
swagger_parser/test/e2e/tests/preserve_schema_casing/expected_files/models/user.dart	Expected model output showing preserved schema casing in type refs/imports.
swagger_parser/test/e2e/tests/preserve_schema_casing/expected_files/models/k_user_status.dart	Expected enum output preserving kUserStatus.
swagger_parser/test/e2e/tests/preserve_schema_casing/expected_files/models/i_os_device.dart	Expected model output preserving iOSDevice.
swagger_parser/test/e2e/tests/preserve_schema_casing/expected_files/models/xml_http_request.dart	Expected model output preserving XMLHttpRequest.
swagger_parser/test/e2e/tests/preserve_schema_casing/expected_files/models/url.dart	Expected typedef output preserving URL.
swagger_parser/pubspec.yaml	Bumps package version to 1.44.0.
swagger_parser/CHANGELOG.md	Documents the new preserve_schema_casing option.

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