Add virtual DeserializeXmlValue and SerializeXmlValue APIs to ScmTypeFactory by Copilot · Pull Request #10186 · microsoft/typespec

Copilot · 2026-03-27T22:01:30Z

ScmTypeFactory has virtual DeserializeJsonValue/SerializeJsonValue for JSON but lacks XML equivalents, preventing extending generators from overriding XML serialization for types like Etag.

Changes

ScmTypeFactory.cs — Added virtual methods DeserializeXmlValue (returns ValueExpression) and SerializeXmlValue (returns ValueExpression), enabling extending generators to override XML serialization
MrwSerializationTypeDefinition.Xml.cs — Replaced private CreateXmlDeserializeValueExpression and CreateXmlSerializeValueExpression with internal static core methods (DeserializeXmlValueCore, SerializeXmlValueCore). Updated callers to route through ScmCodeModelGenerator.Instance.TypeFactory for overrideability, matching the JSON pattern.
XmlDeserializationTests.cs — Added unit tests for DeserializeXmlValueCore covering primitive types, DateTimeOffset, and TimeSpan
XmlSerializationTests.cs — Added unit tests for SerializeXmlValueCore covering primitive types, DateTimeOffset, and TimeSpan. Added TestData-validated override tests demonstrating custom type factory overrides for both serialize and deserialize directions.

// Extending generators can now override XML value serialization:
public override ValueExpression DeserializeXmlValue(
    CSharpType valueType,
    ScopedApi<XElement> element,
    ScopedApi<ModelReaderWriterOptions> mrwOptionsParameter,
    SerializationFormat format)
{
    if (valueType.FrameworkType == typeof(ETag))
        return New.Instance<ETag>(element.Value());

    return base.DeserializeXmlValue(valueType, element, mrwOptionsParameter, format);
}

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…cmTypeFactory Agent-Logs-Url: https://github.com/microsoft/typespec/sessions/d5c279ee-c360-42a7-970b-30add42ea465 Co-authored-by: jorgerangel-msft <102122018+jorgerangel-msft@users.noreply.github.com>

Agent-Logs-Url: https://github.com/microsoft/typespec/sessions/d5c279ee-c360-42a7-970b-30add42ea465 Co-authored-by: jorgerangel-msft <102122018+jorgerangel-msft@users.noreply.github.com>

.chronus/changes/add-xml-serialize-deserialize-value-apis-2026-3-27.md

Agent-Logs-Url: https://github.com/microsoft/typespec/sessions/4d2deae7-13ce-4e8a-bf7c-0084380adacb Co-authored-by: jorgerangel-msft <102122018+jorgerangel-msft@users.noreply.github.com>

jorgerangel-msft

@copilot ensure all tests are passing. Also rerun the Generate.ps1 script

jorgerangel-msft · 2026-03-27T22:17:24Z

...Microsoft.TypeSpec.Generator.ClientModel/src/Providers/MrwSerializationTypeDefinition.Xml.cs

            };
        }

+        internal static ValueExpression DeserializeXmlValueCore(


@copilot can we just replace the CreateXmlDeserializeValueExpression method with this method? The contents should be unchanged from CreateXmlDeserializeValueExpression.

Done in 4772098. CreateXmlDeserializeValueExpression has been replaced with DeserializeXmlValueCore (internal static), and callers now route through ScmCodeModelGenerator.Instance.TypeFactory.DeserializeXmlValue(...) matching the JSON pattern.

jorgerangel-msft · 2026-03-27T22:18:21Z

...Microsoft.TypeSpec.Generator.ClientModel/src/Providers/MrwSerializationTypeDefinition.Xml.cs

+            return CreateXmlDeserializePrimitiveExpression(element, valueType, format);
+        }
+
+        internal static MethodBodyStatement SerializeXmlValueCore(


@copilot can we just replace the CreateXmlSerializeValueExpression method with this? The body should be the same as CreateXmlSerializeValueExpression.

Done in 4772098. CreateXmlSerializeValueExpression has been replaced with SerializeXmlValueCore (internal static, returning ValueExpression with the same body), and callers now route through ScmCodeModelGenerator.Instance.TypeFactory.SerializeXmlValue(...).

jorgerangel-msft · 2026-03-27T22:18:43Z

...Microsoft.TypeSpec.Generator.ClientModel/src/Providers/MrwSerializationTypeDefinition.Xml.cs

+            };
+        }
+
+        internal static ValueExpression SerializeXmlValueExpressionCore(ValueExpression value, CSharpType valueType, SerializationFormat serializationFormat)


@copilot why is this needed?

Removed in 4772098. It was a duplicate of CreateXmlSerializeValueExpression. Now SerializeXmlValueCore returns ValueExpression directly (same body as the old method), so SerializeXmlValueExpressionCore is no longer needed.

jorgerangel-msft · 2026-03-27T22:19:09Z

.../http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/ScmTypeFactory.cs

+            ScopedApi<XElement> element,
+            ScopedApi<ModelReaderWriterOptions> mrwOptionsParameter,
+            SerializationFormat format)
+            => MrwSerializationTypeDefinition.DeserializeXmlValueCore(valueType, element, mrwOptionsParameter, format);


@copilot add indentation to the lambda

Done in 4772098.

jorgerangel-msft · 2026-03-27T22:19:16Z

.../http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/ScmTypeFactory.cs

+            ScopedApi<XmlWriter> xmlWriter,
+            ScopedApi<ModelReaderWriterOptions> mrwOptionsParameter,
+            SerializationFormat serializationFormat)
+            => MrwSerializationTypeDefinition.SerializeXmlValueCore(valueType, value, xmlWriter, mrwOptionsParameter, serializationFormat);


@copilot add indentation to the lambda

Done in 4772098.

jorgerangel-msft · 2026-03-27T22:20:33Z

...tModel/test/Providers/MrwSerializationTypeDefinitions/MrwSerializationTypeDefinitionTests.cs

+        [TestCase(typeof(byte), SerializationFormat.Default, ExpectedResult = "((byte)((int)foo))")]
+        [TestCase(typeof(sbyte), SerializationFormat.Default, ExpectedResult = "((sbyte)((int)foo))")]
+        [TestCase(typeof(short), SerializationFormat.Default, ExpectedResult = "((short)((int)foo))")]
+        public string TestDeserializeXmlValueCore_PrimitiveTypes(Type type, SerializationFormat format)


@copilot this new test should go in XmlDeserializationTests

Done in 4772098 — deserialization tests moved to XmlDeserializationTests.cs.

jorgerangel-msft · 2026-03-27T22:20:42Z

...tModel/test/Providers/MrwSerializationTypeDefinitions/MrwSerializationTypeDefinitionTests.cs

+        }
+
+        [Test]
+        public void TestSerializeXmlValueCore_Int()


@copilot this new test should go in XmlSserializationTests

Done in 4772098 — serialization tests moved to XmlSerializationTests.cs.

jorgerangel-msft · 2026-03-27T22:22:56Z

...tModel/test/Providers/MrwSerializationTypeDefinitions/MrwSerializationTypeDefinitionTests.cs

+        }
+
+        [Test]
+        public void TestSerializeXmlValueCore_String()


@copilot use TestData to validate the serialization tests.

Done in 4772098. Added TestData-based validation for two override tests: SerializeXmlValueOverride_CustomTypeSerialization and DeserializeXmlValueOverride_CustomTypeDeserialization, which compare full generated output against expected .cs files.

jorgerangel-msft · 2026-03-27T22:23:39Z

...tModel/test/Providers/MrwSerializationTypeDefinitions/MrwSerializationTypeDefinitionTests.cs

+
+        [TestCase(SerializationFormat.Duration_ISO8601)]
+        [TestCase(SerializationFormat.Duration_Constant)]
+        public void TestSerializeXmlValueCore_TimeSpan(SerializationFormat format)


@copilot we should also add a test case where we override the new APIs and add custom serialization for a new type, or existing type.

Done in 4772098. Added two override tests using Moq:

SerializeXmlValueOverride_CustomTypeSerialization — overrides SerializeXmlValue for string type to return value.ToString() and validates output with TestData

DeserializeXmlValueOverride_CustomTypeDeserialization — overrides DeserializeXmlValue for string type to return element.ToString() and validates output with TestData

…ds, move tests to XML test files, add override tests Agent-Logs-Url: https://github.com/microsoft/typespec/sessions/fb4989f3-4f35-4758-9fbc-8e1a87f8c2c4 Co-authored-by: jorgerangel-msft <102122018+jorgerangel-msft@users.noreply.github.com>

Copilot · 2026-03-27T22:58:26Z

@copilot ensure all tests are passing. Also rerun the Generate.ps1 script

Done in 4772098. All 1264 tests pass and Generate.ps1 ran successfully with no diff in generated output.

Initial plan

094d982

Copilot AI assigned Copilot and jorgerangel-msft Mar 27, 2026

Copilot started work on behalf of jorgerangel-msft March 27, 2026 22:01 View session

Copilot AI linked an issue Mar 27, 2026 that may be closed by this pull request

Add Deserialize + Serialize Xml Value APIs for XML Serialization #10185

Open

feat: add DeserializeXmlValue and SerializeXmlValue virtual APIs to S…

7804246

…cmTypeFactory Agent-Logs-Url: https://github.com/microsoft/typespec/sessions/d5c279ee-c360-42a7-970b-30add42ea465 Co-authored-by: jorgerangel-msft <102122018+jorgerangel-msft@users.noreply.github.com>

microsoft-github-policy-service bot added the emitter:client:csharp Issue for the C# client emitter: @typespec/http-client-csharp label Mar 27, 2026

chore: add changelog entry for XML serialization value APIs

33a49d5

Agent-Logs-Url: https://github.com/microsoft/typespec/sessions/d5c279ee-c360-42a7-970b-30add42ea465 Co-authored-by: jorgerangel-msft <102122018+jorgerangel-msft@users.noreply.github.com>

Copilot AI changed the title ~~[WIP] Add deserialize and serialize XML value APIs for XML serialization~~ Add virtual DeserializeXmlValue and SerializeXmlValue APIs to ScmTypeFactory Mar 27, 2026

jorgerangel-msft reviewed Mar 27, 2026

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Copilot AI requested a review from jorgerangel-msft March 27, 2026 22:15

revert: remove changelog entry outside http-client-csharp folder

ace8dbb

Agent-Logs-Url: https://github.com/microsoft/typespec/sessions/4d2deae7-13ce-4e8a-bf7c-0084380adacb Co-authored-by: jorgerangel-msft <102122018+jorgerangel-msft@users.noreply.github.com>

Copilot finished work on behalf of jorgerangel-msft March 27, 2026 22:19

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Copilot finished work on behalf of jorgerangel-msft March 27, 2026 22:20

jorgerangel-msft reviewed Mar 27, 2026

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Copilot started work on behalf of jorgerangel-msft March 27, 2026 22:24 View session

Copilot finished work on behalf of jorgerangel-msft March 27, 2026 22:59

Copilot AI requested a review from jorgerangel-msft March 27, 2026 22:59

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