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Fix Swift oneOf discriminator decoding with enumUnknownDefaultCase #22635

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Fix Swift oneOf discriminator decoding with enumUnknownDefaultCase #22635

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6f6f05c
Fix Swift oneOf discriminator decoding with enumUnknownDefaultCase
lastMove Jan 8, 2026
4165a5d
Remove comments from modelOneOf templates
lastMove Jan 8, 2026
96b6a88
Add tests for oneOf discriminator-first decoding
lastMove Jan 8, 2026
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33 changes: 32 additions & 1 deletion modules/openapi-generator/src/main/resources/swift5/modelOneOf.mustache
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Original file line number Diff line number Diff line change
Expand Up @@ -14,13 +14,43 @@
try container.encode(value)
{{/oneOf}}
{{#oneOfUnknownDefaultCase}}
case unknownDefaultOpenApi(let type):
case .unknownDefaultOpenApi:
try container.encodeNil()
{{/oneOfUnknownDefaultCase}}
}
}

{{#discriminator}}
private enum DiscriminatorCodingKey: String, CodingKey {
case {{discriminator.propertyName}} = "{{discriminator.propertyBaseName}}"
}
{{/discriminator}}

public init(from decoder: Decoder) throws {
{{#discriminator}}
let keyedContainer = try decoder.container(keyedBy: DiscriminatorCodingKey.self)
let discriminatorValue = try keyedContainer.decode(String.self, forKey: .{{discriminator.propertyName}})

switch discriminatorValue {
{{#discriminator.mappedModels}}
case "{{mappingName}}":
self = .type{{modelName}}(try {{modelName}}(from: decoder))
{{/discriminator.mappedModels}}
default:
{{#oneOfUnknownDefaultCase}}
self = .unknownDefaultOpenApi
{{/oneOfUnknownDefaultCase}}
{{^oneOfUnknownDefaultCase}}
throw DecodingError.dataCorrupted(
DecodingError.Context(
codingPath: decoder.codingPath,
debugDescription: "Unknown discriminator value '\(discriminatorValue)' for {{classname}}"
)
)
{{/oneOfUnknownDefaultCase}}
}
{{/discriminator}}
{{^discriminator}}
let container = try decoder.singleValueContainer()
{{#oneOf}}
{{#-first}}
Expand All @@ -39,5 +69,6 @@
throw DecodingError.typeMismatch(Self.Type.self, .init(codingPath: decoder.codingPath, debugDescription: "Unable to decode instance of {{classname}}"))
{{/oneOfUnknownDefaultCase}}
}
{{/discriminator}}
}
}
33 changes: 32 additions & 1 deletion modules/openapi-generator/src/main/resources/swift6/modelOneOf.mustache
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Original file line number Diff line number Diff line change
Expand Up @@ -14,13 +14,43 @@
try container.encode(value)
{{/oneOf}}
{{#oneOfUnknownDefaultCase}}
case unknownDefaultOpenApi(let type):
case .unknownDefaultOpenApi:
try container.encodeNil()
{{/oneOfUnknownDefaultCase}}
}
}

{{#discriminator}}
private enum DiscriminatorCodingKey: String, CodingKey {
case {{discriminator.propertyName}} = "{{discriminator.propertyBaseName}}"
}
{{/discriminator}}

public init(from decoder: Decoder) throws {
{{#discriminator}}
let keyedContainer = try decoder.container(keyedBy: DiscriminatorCodingKey.self)
let discriminatorValue = try keyedContainer.decode(String.self, forKey: .{{discriminator.propertyName}})

switch discriminatorValue {
{{#discriminator.mappedModels}}
case "{{mappingName}}":
self = .type{{#transformArrayType}}{{modelName}}{{/transformArrayType}}(try {{modelName}}(from: decoder))
{{/discriminator.mappedModels}}
default:
{{#oneOfUnknownDefaultCase}}
self = .unknownDefaultOpenApi
{{/oneOfUnknownDefaultCase}}
{{^oneOfUnknownDefaultCase}}
throw DecodingError.dataCorrupted(
DecodingError.Context(
codingPath: decoder.codingPath,
debugDescription: "Unknown discriminator value '\(discriminatorValue)' for {{classname}}"
)
)
{{/oneOfUnknownDefaultCase}}
}
{{/discriminator}}
{{^discriminator}}
let container = try decoder.singleValueContainer()
{{#oneOf}}
{{#-first}}
Expand All @@ -39,5 +69,6 @@
throw DecodingError.typeMismatch(Self.Type.self, .init(codingPath: decoder.codingPath, debugDescription: "Unable to decode instance of {{classname}}"))
{{/oneOfUnknownDefaultCase}}
}
{{/discriminator}}
}
}
38 changes: 38 additions & 0 deletions ...napi-generator/src/test/java/org/openapitools/codegen/swift5/Swift5ClientCodegenTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -317,4 +317,42 @@ public void oneOfFormParameterTest() {

}

@Test(description = "test oneOf with discriminator generates discriminator-first decoding", enabled = true)
public void oneOfDiscriminatorFirstDecodingTest() throws IOException {
Path target = Files.createTempDirectory("test");
File output = target.toFile();
try {
final CodegenConfigurator configurator = new CodegenConfigurator()
.setGeneratorName("swift5")
.setInputSpec("src/test/resources/3_0/oneOfDiscriminator.yaml")
.setOutputDir(target.toAbsolutePath().toString());

final ClientOptInput clientOptInput = configurator.toClientOptInput();
DefaultGenerator generator = new DefaultGenerator(false);
generator.setGeneratorPropertyDefault(CodegenConstants.MODELS, "true");
generator.setGeneratorPropertyDefault(CodegenConstants.APIS, "false");
generator.setGeneratorPropertyDefault(CodegenConstants.SUPPORTING_FILES, "false");

List<File> files = generator.opts(clientOptInput).generate();

File modelFile = files.stream()
.filter(f -> f.getName().equals("FruitOneOfEnumMappingDisc.swift"))
.findFirst()
.orElseThrow(() -> new RuntimeException("FruitOneOfEnumMappingDisc.swift not found"));

String content = Files.readString(modelFile.toPath());

// Verify discriminator-first decoding pattern
Assert.assertTrue(content.contains("private enum DiscriminatorCodingKey: String, CodingKey"));
Assert.assertTrue(content.contains("let keyedContainer = try decoder.container(keyedBy: DiscriminatorCodingKey.self)"));
Assert.assertTrue(content.contains("switch discriminatorValue"));
Assert.assertTrue(content.contains("case \"APPLE\":"));
Assert.assertTrue(content.contains("self = .typeAppleOneOfEnumMappingDisc(try AppleOneOfEnumMappingDisc(from: decoder))"));
Assert.assertFalse(content.contains("if let value = try? container.decode(AppleOneOfEnumMappingDisc.self)"));

} finally {
output.deleteOnExit();
}
}

}
38 changes: 38 additions & 0 deletions ...napi-generator/src/test/java/org/openapitools/codegen/swift6/Swift6ClientCodegenTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -363,4 +363,42 @@ public void oneOfArrayTypeNamesTest() throws IOException {
output.deleteOnExit();
}
}

@Test(description = "test oneOf with discriminator generates discriminator-first decoding", enabled = true)
public void oneOfDiscriminatorFirstDecodingTest() throws IOException {
Path target = Files.createTempDirectory("test");
File output = target.toFile();
try {
final CodegenConfigurator configurator = new CodegenConfigurator()
.setGeneratorName("swift6")
.setInputSpec("src/test/resources/3_0/oneOfDiscriminator.yaml")
.setOutputDir(target.toAbsolutePath().toString());

final ClientOptInput clientOptInput = configurator.toClientOptInput();
DefaultGenerator generator = new DefaultGenerator(false);
generator.setGeneratorPropertyDefault(CodegenConstants.MODELS, "true");
generator.setGeneratorPropertyDefault(CodegenConstants.APIS, "false");
generator.setGeneratorPropertyDefault(CodegenConstants.SUPPORTING_FILES, "false");

List<File> files = generator.opts(clientOptInput).generate();

File modelFile = files.stream()
.filter(f -> f.getName().equals("FruitOneOfEnumMappingDisc.swift"))
.findFirst()
.orElseThrow(() -> new RuntimeException("FruitOneOfEnumMappingDisc.swift not found"));

String content = Files.readString(modelFile.toPath());

// Verify discriminator-first decoding pattern
Assert.assertTrue(content.contains("private enum DiscriminatorCodingKey: String, CodingKey"));
Assert.assertTrue(content.contains("let keyedContainer = try decoder.container(keyedBy: DiscriminatorCodingKey.self)"));
Assert.assertTrue(content.contains("switch discriminatorValue"));
Assert.assertTrue(content.contains("case \"APPLE\":"));
Assert.assertTrue(content.contains("self = .typeAppleOneOfEnumMappingDisc(try AppleOneOfEnumMappingDisc(from: decoder))"));
Assert.assertFalse(content.contains("if let value = try? container.decode(AppleOneOfEnumMappingDisc.self)"));

} finally {
output.deleteOnExit();
}
}
}
1 change: 1 addition & 0 deletions samples/client/petstore/swift5/oneOf/PetstoreClient/Classes/OpenAPIs/Models/Fruit.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,7 @@ public enum Fruit: Codable, JSONEncodable, Hashable {
}
}


public init(from decoder: Decoder) throws {
let container = try decoder.singleValueContainer()
if let value = try? container.decode(Apple.self) {
Expand Down
1 change: 1 addition & 0 deletions samples/client/petstore/swift6/oneOf/PetstoreClient/Classes/OpenAPIs/Models/Fruit.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,7 @@ public enum Fruit: Sendable, Codable, ParameterConvertible, Hashable {
}
}


public init(from decoder: Decoder) throws {
let container = try decoder.singleValueContainer()
if let value = try? container.decode(Apple.self) {
Expand Down
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