Inline OneOf validation rules into TypeAndFieldRule

Copilot · andimarek · Copilot · commit 4890f7f54836 · 2026-02-19T02:05:02.000Z
Co-authored-by: andimarek &lt;1706744+andimarek@users.noreply.github.com&gt;
diff --git a/src/main/java/graphql/schema/validation/OneOfInputObjectRules.java b/src/main/java/graphql/schema/validation/OneOfInputObjectRules.java
diff --git a/src/main/java/graphql/schema/validation/SchemaValidator.java b/src/main/java/graphql/schema/validation/SchemaValidator.java
@@ -25,7 +25,6 @@ public SchemaValidator() {
         rules.add(new AppliedDirectivesAreValid());
         rules.add(new AppliedDirectiveArgumentsAreValid());
         rules.add(new InputAndOutputTypesUsedAppropriately());
-        rules.add(new OneOfInputObjectRules());
         rules.add(new DeprecatedInputObjectAndArgumentsAreValid());
     }
 
diff --git a/src/main/java/graphql/schema/validation/TypeAndFieldRule.java b/src/main/java/graphql/schema/validation/TypeAndFieldRule.java
@@ -19,11 +19,13 @@
 import graphql.schema.GraphQLTypeUtil;
 import graphql.schema.GraphQLTypeVisitorStub;
 import graphql.schema.GraphQLUnionType;
+import graphql.schema.GraphQLUnmodifiedType;
 import graphql.util.FpKit;
 import graphql.util.TraversalControl;
 import graphql.util.TraverserContext;
 
 import java.util.HashSet;
+import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Set;
 import java.util.function.Predicate;
@@ -91,6 +93,35 @@ public TraversalControl visitGraphQLInputObjectType(GraphQLInputObjectType type,
         }
         SchemaValidationErrorCollector errorCollector = context.getVarFromParents(SchemaValidationErrorCollector.class);
         validateInputObject((GraphQLInputObjectType) type, errorCollector);
+        
+        // OneOf validation: check if OneOf input types are inhabited
+        if (type.isOneOf()) {
+            if (!canBeProvidedAFiniteValue(type, new LinkedHashSet<>())) {
+                String message = String.format("OneOf Input Object %s must be inhabited but all fields recursively reference only other OneOf Input Objects forming an unresolvable cycle.", type.getName());
+                errorCollector.addError(new SchemaValidationError(SchemaValidationErrorType.OneOfNotInhabited, message));
+            }
+        }
+        
+        return TraversalControl.CONTINUE;
+    }
+
+    @Override
+    public TraversalControl visitGraphQLInputObjectField(GraphQLInputObjectField inputObjectField, TraverserContext<GraphQLSchemaElement> context) {
+        GraphQLInputObjectType inputObjectType = (GraphQLInputObjectType) context.getParentNode();
+        if (!inputObjectType.isOneOf()) {
+            return TraversalControl.CONTINUE;
+        }
+        SchemaValidationErrorCollector errorCollector = context.getVarFromParents(SchemaValidationErrorCollector.class);
+        // OneOf validation: error messages taken from the reference implementation
+        if (inputObjectField.hasSetDefaultValue()) {
+            String message = String.format("OneOf input field %s.%s cannot have a default value.", inputObjectType.getName(), inputObjectField.getName());
+            errorCollector.addError(new SchemaValidationError(SchemaValidationErrorType.OneOfDefaultValueOnField, message));
+        }
+
+        if (GraphQLTypeUtil.isNonNull(inputObjectField.getType())) {
+            String message = String.format("OneOf input field %s.%s must be nullable.", inputObjectType.getName(), inputObjectField.getName());
+            errorCollector.addError(new SchemaValidationError(SchemaValidationErrorType.OneOfNonNullableField, message));
+        }
         return TraversalControl.CONTINUE;
     }
 
@@ -121,6 +152,32 @@ private void validateInputObject(GraphQLInputObjectType type, SchemaValidationEr
         }
     }
 
+    private boolean canBeProvidedAFiniteValue(GraphQLInputObjectType oneOfInputObject, Set<GraphQLInputObjectType> visited) {
+        if (visited.contains(oneOfInputObject)) {
+            return false;
+        }
+        Set<GraphQLInputObjectType> nextVisited = new LinkedHashSet<>(visited);
+        nextVisited.add(oneOfInputObject);
+        for (GraphQLInputObjectField field : oneOfInputObject.getFieldDefinitions()) {
+            GraphQLType fieldType = field.getType();
+            if (GraphQLTypeUtil.isList(fieldType)) {
+                return true;
+            }
+            GraphQLUnmodifiedType namedFieldType = GraphQLTypeUtil.unwrapAll(fieldType);
+            if (!(namedFieldType instanceof GraphQLInputObjectType)) {
+                return true;
+            }
+            GraphQLInputObjectType inputFieldType = (GraphQLInputObjectType) namedFieldType;
+            if (!inputFieldType.isOneOf()) {
+                return true;
+            }
+            if (canBeProvidedAFiniteValue(inputFieldType, nextVisited)) {
+                return true;
+            }
+        }
+        return false;
+    }
+
     private void validateUnion(GraphQLUnionType type, SchemaValidationErrorCollector errorCollector) {
         List<GraphQLNamedOutputType> memberTypes = type.getTypes();
         if (memberTypes.size() == 0) {
diff --git a/src/test/groovy/graphql/schema/validation/SchemaValidatorTest.groovy b/src/test/groovy/graphql/schema/validation/SchemaValidatorTest.groovy
@@ -11,15 +11,14 @@ class SchemaValidatorTest extends Specification {
         def validator = new SchemaValidator()
         def rules = validator.rules
         then:
-        rules.size() == 9
+        rules.size() == 8
         rules[0] instanceof NoUnbrokenInputCycles
         rules[1] instanceof TypesImplementInterfaces
         rules[2] instanceof TypeAndFieldRule
         rules[3] instanceof DefaultValuesAreValid
         rules[4] instanceof AppliedDirectivesAreValid
         rules[5] instanceof AppliedDirectiveArgumentsAreValid
         rules[6] instanceof InputAndOutputTypesUsedAppropriately
-        rules[7] instanceof OneOfInputObjectRules
-        rules[8] instanceof DeprecatedInputObjectAndArgumentsAreValid
+        rules[7] instanceof DeprecatedInputObjectAndArgumentsAreValid
     }
 }

Original file line number	Diff line number	Diff line change
`@@ -25,7 +25,6 @@ public SchemaValidator() {`
`25`	`25`	`rules.add(new AppliedDirectivesAreValid());`
`26`	`26`	`rules.add(new AppliedDirectiveArgumentsAreValid());`
`27`	`27`	`rules.add(new InputAndOutputTypesUsedAppropriately());`
`28`		`- rules.add(new OneOfInputObjectRules());`
`29`	`28`	`rules.add(new DeprecatedInputObjectAndArgumentsAreValid());`
`30`	`29`	`}`
`31`	`30`