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Support SimpleTypes defined as a union of enums as enums #795

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Support SimpleTypes defined as a union of enums as enums #795

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237db58
Support SimpleTypes defined as a union of enums as an enum
Apr 20, 2026
ca11feb
Update schema2proto-lib/src/main/java/no/entur/schema2proto/compatibi…
erlendnils1 Apr 21, 2026
faf997c
Update al union handling to make distinction between all enum unions …
Apr 21, 2026
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62 changes: 58 additions & 4 deletions schema2proto-lib/src/main/java/no/entur/schema2proto/generateproto/SchemaParser.java
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Original file line number Diff line number Diff line change
Expand Up @@ -84,6 +84,7 @@
import com.sun.xml.xsom.XSSimpleType;
import com.sun.xml.xsom.XSTerm;
import com.sun.xml.xsom.XSType;
import com.sun.xml.xsom.XSUnionSimpleType;
import com.sun.xml.xsom.impl.ElementDecl;
import com.sun.xml.xsom.parser.XSOMParser;
import com.sun.xml.xsom.util.DomAnnotationParserFactory;
Expand Down Expand Up @@ -246,12 +247,65 @@ private String processSimpleType(XSSimpleType xs, String elementName) {
} else if (xs.isList()) {
nestingLevel--;
return processSimpleType(xs.asList().getItemType(), null);
} else if (isEnumUnion(xs)) {
createEnumFromUnion(typeName, xs.asUnion());
}

nestingLevel--;
return typeName;
}

private boolean isNonEnumUnion(XSSimpleType xs) {
return xs.isUnion() && !isEnumUnion(xs);
}

private boolean isEnumUnion(XSSimpleType xs) {
if (!xs.isUnion()) {
return false;
}
XSUnionSimpleType unionType = xs.asUnion();
boolean allMembersAreEnums = true;

for (int i = 0; i < unionType.getMemberSize(); i++) {
XSSimpleType member = unionType.getMember(i);
if (!member.isRestriction() || member.getFacet(XSFacet.FACET_ENUMERATION) == null) {
allMembersAreEnums = false;
break;
}
}
return allMembersAreEnums;
}

private void createEnumFromUnion(String typeName, XSUnionSimpleType unionType) {
Type protoType = getType(unionType.getTargetNamespace(), typeName);
if (protoType == null) {
Location location = getLocation(unionType);
List<EnumConstant> constants = new ArrayList<>();
int counter = 1;
Set<String> addedValues = new HashSet<>();

for (int i = 0; i < unionType.getMemberSize(); i++) {
XSRestrictionSimpleType member = unionType.getMember(i).asRestriction();
for (XSFacet facet : member.getDeclaredFacets()) {
String enumValue = facet.getValue().value;
if (addedValues.add(enumValue)) {
String doc = resolveDocumentationAnnotation(facet, false);
List<OptionElement> optionElements = new ArrayList<>();
constants.add(new EnumConstant(location, enumValue, counter++, doc, new Options(Options.ENUM_VALUE_OPTIONS, optionElements)));
}
}
}

List<OptionElement> enumOptionElements = new ArrayList<>();
Options enumOptions = new Options(Options.ENUM_OPTIONS, enumOptionElements);
String doc = resolveDocumentationAnnotation(unionType, false);

ProtoType definedProtoType = ProtoType.get(typeName);
EnumType enumType = new EnumType(definedProtoType, location, doc, typeName, constants, new ArrayList<>(), enumOptions);
addType(unionType.getTargetNamespace(), enumType);
}
Comment on lines +279 to +306

Copilot AI Apr 20, 2026

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createEnumFromUnion always adds the generated enum at file scope. If a union-of-enums occurs as a local/anonymous simpleType (e.g., inline on an element), this will create a global enum with a generated name rather than nesting it under the enclosing message (unlike createEnum(...) which supports enclosingType). If local union-of-enums should be supported, consider threading through the enclosing message (or otherwise aligning scoping rules) to avoid polluting the global namespace and to keep naming consistent.

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}

private void addField(MessageType message, Field newField) {
addField(message, null, newField);
}
Expand Down Expand Up @@ -502,8 +556,8 @@ public String findFieldType(XSType type) {
XSListSimpleType asList = type.asSimpleType().asList();
XSSimpleType itemType = asList.getItemType();
typeName = itemType.getName();
} else if (type.asSimpleType().isUnion()) {
typeName = DEFAULT_PROTO_PRIMITIVE; // Union always resolves to string
} else if (isNonEnumUnion(type.asSimpleType())) {
typeName = DEFAULT_PROTO_PRIMITIVE; // Non enum union always resolves to string
} else {
typeName = type.asSimpleType().getBaseType().getName();
}
Expand Down Expand Up @@ -711,7 +765,7 @@ private MessageType processComplexType(XSComplexType complexType, String element
}

String name;
if (xsSimpleType.isUnion()) {
if (isNonEnumUnion(xsSimpleType)) {
name = DEFAULT_PROTO_PRIMITIVE;
} else {
name = xsSimpleType.getName();
Expand Down Expand Up @@ -840,7 +894,7 @@ private void processAttribute(MessageType messageType, Set<Object> processedXmlO
XSAttributeDecl decl = attr.getDecl();
XSSimpleType type = decl.getType();

if (type.getPrimitiveType() != null || type.isList() || type.isUnion()) {
if (type.getPrimitiveType() != null || type.isList() || isNonEnumUnion(type)) {
String fieldName = decl.getName();
String doc = resolveDocumentationAnnotation(decl, false);
int tag = messageType.getNextFieldNum();
Expand Down
6 changes: 6 additions & 0 deletions schema2proto-lib/src/test/java/no/entur/schema2proto/generateproto/SchemaParserTest.java
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Expand Up @@ -179,6 +179,12 @@ public void testUnion() throws IOException {
compareExpectedAndGenerated(expectedRootFolder, "default/union.proto", generatedRootFolder, "default/default.proto");
}

@Test
public void testUnionOfEnums() throws IOException {
generateProtobufNoOptions("basic/union-of-enums.xsd");
compareExpectedAndGenerated(expectedRootFolder, "default/union-of-enums.proto", generatedRootFolder, "default/default.proto");
}
Comment on lines +182 to +186

Copilot AI Apr 20, 2026

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This test only asserts that a union-of-enums simpleType produces an enum declaration, but it doesn’t cover the key behavior of using that enum when the union type is referenced by an element/attribute/simpleContent. Adding an XSD fixture where UnionEnumeration is used as a field type would help prevent regressions where unions still resolve to string.

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// @Test
public void testValidationRules() throws IOException {
generateProtobufNoOptions("basic/validationrules.xsd");
Expand Down
26 changes: 26 additions & 0 deletions schema2proto-lib/src/test/resources/expectedproto/basic/default/union-of-enums.proto
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@@ -0,0 +1,26 @@
// default.proto at 0:0
syntax = "proto3";
package default;

enum Enum1 {
// Default
ENUM1_UNSPECIFIED = 0;
ENUM1_E_1_VAL_1 = 1;
ENUM1_E_1_VAL_2 = 2;
}

enum Enum2 {
// Default
ENUM2_UNSPECIFIED = 0;
ENUM2_E_2_VAL_1 = 1;
ENUM2_E_2_VAL_2 = 2;
}

enum UnionEnumeration {
// Default
UNION_ENUMERATION_UNSPECIFIED = 0;
UNION_ENUMERATION_E_1_VAL_1 = 1;
UNION_ENUMERATION_E_1_VAL_2 = 2;
UNION_ENUMERATION_E_2_VAL_1 = 3;
UNION_ENUMERATION_E_2_VAL_2 = 4;
}
23 changes: 23 additions & 0 deletions schema2proto-lib/src/test/resources/xsd/basic/union-of-enums.xsd
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@@ -0,0 +1,23 @@
<?xml version="1.0" encoding="UTF-8"?>

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" version="1.0">

<xsd:simpleType name="UnionEnumeration">
<xsd:union memberTypes="Enum1 Enum2"/>
</xsd:simpleType>

<xsd:simpleType name="Enum1">
<xsd:restriction base="xsd:string">
<xsd:enumeration value="e1val1"/>
<xsd:enumeration value="e1val2"/>
</xsd:restriction>
</xsd:simpleType>

<xsd:simpleType name="Enum2">
<xsd:restriction base="xsd:string">
<xsd:enumeration value="e2val1"/>
<xsd:enumeration value="e2val2"/>
</xsd:restriction>
</xsd:simpleType>

</xsd:schema>
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