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fix(reader): preserve Null flag when nullable appears before type in V3.0/V3.1/V3.2 deserializers #2853

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Merged
baywet merged 3 commits into from
May 26, 2026
+46 −4
Merged

fix(reader): preserve Null flag when nullable appears before type in V3.0/V3.1/V3.2 deserializers #2853

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Copilot May 26, 2026
94b606d
fix(reader): preserve nullable Null flag when type appears after null…
Copilot May 26, 2026
de72b1d
test(reader): add nullable-before-type tests for V3.0 and V3.2
Copilot May 26, 2026
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7 changes: 5 additions & 2 deletions src/Microsoft.OpenApi/Reader/V31/OpenApiSchemaDeserializer.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -198,14 +198,17 @@ internal static partial class OpenApiV31Deserializer
"type",
(o, n, doc) =>
{
// Preserve any Null flag set by a preceding "nullable: true" handler
var preserveNull = o.Type.HasValue && o.Type.Value.HasFlag(JsonSchemaType.Null);
if (n is ValueNode)
{
o.Type = n.GetScalarValue()?.ToJsonSchemaType();
var parsedType = n.GetScalarValue()?.ToJsonSchemaType();
o.Type = preserveNull ? parsedType | JsonSchemaType.Null : parsedType;
}
else
{
var list = n.CreateSimpleList((n2, p) => n2.GetScalarValue(), doc);
JsonSchemaType combinedType = 0;
JsonSchemaType combinedType = preserveNull ? JsonSchemaType.Null : 0;
foreach(var type in list.Where(static t => t is not null).Select(static t => t!.ToJsonSchemaType()))
{
combinedType |= type;
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7 changes: 5 additions & 2 deletions src/Microsoft.OpenApi/Reader/V32/OpenApiSchemaDeserializer.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -198,14 +198,17 @@ internal static partial class OpenApiV32Deserializer
"type",
(o, n, doc) =>
{
// Preserve any Null flag set by a preceding "nullable: true" handler
var preserveNull = o.Type.HasValue && o.Type.Value.HasFlag(JsonSchemaType.Null);
if (n is ValueNode)
{
o.Type = n.GetScalarValue()?.ToJsonSchemaType();
var parsedType = n.GetScalarValue()?.ToJsonSchemaType();
o.Type = preserveNull ? parsedType | JsonSchemaType.Null : parsedType;
}
else
{
var list = n.CreateSimpleList((n2, p) => n2.GetScalarValue(), doc);
JsonSchemaType combinedType = 0;
JsonSchemaType combinedType = preserveNull ? JsonSchemaType.Null : 0;
foreach(var type in list.Where(static t => t is not null).Select(static t => t!.ToJsonSchemaType()))
{
combinedType |= type;
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12 changes: 12 additions & 0 deletions test/Microsoft.OpenApi.Readers.Tests/V31Tests/OpenApiSchemaTests.cs
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Expand Up @@ -132,6 +132,18 @@ public void ParseSchemaWithTypeArrayWorks()
Assert.Equivalent(expected, actual);
}

[Theory]
[InlineData(@"{ ""nullable"": true, ""type"": ""string"" }")]
[InlineData(@"{ ""type"": ""string"", ""nullable"": true }")]
public void ParseSchemaWithNullableBeforeOrAfterTypePreservesNullFlag(string schemaJson)
{
// Act
var schema = OpenApiModelFactory.Parse<OpenApiSchema>(schemaJson, OpenApiSpecVersion.OpenApi3_1, new(), out _, "json", SettingsFixture.ReaderSettings);

// Assert
Assert.Equal(JsonSchemaType.String | JsonSchemaType.Null, schema.Type);
}

[Fact]
public void TestSchemaCopyConstructorWithTypeArrayWorks()
{
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12 changes: 12 additions & 0 deletions test/Microsoft.OpenApi.Readers.Tests/V32Tests/OpenApiSchemaTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -131,6 +131,18 @@ public void ParseSchemaWithTypeArrayWorks()
Assert.Equivalent(expected, actual);
}

[Theory]
[InlineData(@"{ ""nullable"": true, ""type"": ""string"" }")]
[InlineData(@"{ ""type"": ""string"", ""nullable"": true }")]
public void ParseSchemaWithNullableBeforeOrAfterTypePreservesNullFlag(string schemaJson)
{
// Act
var schema = OpenApiModelFactory.Parse<OpenApiSchema>(schemaJson, OpenApiSpecVersion.OpenApi3_2, new(), out _, "json", SettingsFixture.ReaderSettings);

// Assert
Assert.Equal(JsonSchemaType.String | JsonSchemaType.Null, schema.Type);
}

[Fact]
public void TestSchemaCopyConstructorWithTypeArrayWorks()
{
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12 changes: 12 additions & 0 deletions test/Microsoft.OpenApi.Readers.Tests/V3Tests/OpenApiSchemaTests.cs
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Expand Up @@ -133,6 +133,18 @@ public void ParsePathFragmentShouldSucceed()
}, openApiAny);
}

[Theory]
[InlineData(@"{ ""nullable"": true, ""type"": ""string"" }")]
[InlineData(@"{ ""type"": ""string"", ""nullable"": true }")]
public void ParseSchemaWithNullableBeforeOrAfterTypePreservesNullFlag(string schemaJson)
{
// Act
var schema = OpenApiModelFactory.Parse<OpenApiSchema>(schemaJson, OpenApiSpecVersion.OpenApi3_0, new(), out _, "json", SettingsFixture.ReaderSettings);

// Assert
Assert.Equal(JsonSchemaType.String | JsonSchemaType.Null, schema.Type);
}

[Fact]
public void ParseDictionarySchemaShouldSucceed()
{
Expand Down
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