Fix for #409

Author: KammererTob

src/main/kotlin/graphql/kickstart/tools/SchemaParser.kt

@@ -81,7 +81,7 @@ class SchemaParser internal constructor(
         val inputObjects: MutableList<GraphQLInputObjectType> = mutableListOf()
         inputObjectDefinitions.forEach {
             if (inputObjects.none { io -> io.name == it.name }) {
-                inputObjects.add(createInputObject(it, inputObjects))
+                inputObjects.add(createInputObject(it, inputObjects, mutableSetOf()))
             }
         }
         val interfaces = interfaceDefinitions.map { createInterfaceObject(it, inputObjects) }
@@ -173,7 +173,8 @@ class SchemaParser internal constructor(
         return output.toTypedArray()
     }
 
-    private fun createInputObject(definition: InputObjectTypeDefinition, inputObjects: List<GraphQLInputObjectType>): GraphQLInputObjectType {
+    private fun createInputObject(definition: InputObjectTypeDefinition, inputObjects: List<GraphQLInputObjectType>,
+                                  referencingInputObjects: MutableSet<String>): GraphQLInputObjectType {
         val extensionDefinitions = inputExtensionDefinitions.filter { it.name == definition.name }
 
         val builder = GraphQLInputObjectType.newInputObject()
@@ -184,14 +185,16 @@ class SchemaParser internal constructor(
 
         builder.withDirectives(*buildDirectives(definition.directives, setOf(), Introspection.DirectiveLocation.INPUT_OBJECT))
 
+        referencingInputObjects.add(definition.name)
+
         (extensionDefinitions + definition).forEach {
             it.inputValueDefinitions.forEach { inputDefinition ->
                 val fieldBuilder = GraphQLInputObjectField.newInputObjectField()
                         .name(inputDefinition.name)
                         .definition(inputDefinition)
                         .description(if (inputDefinition.description != null) inputDefinition.description.content else getDocumentation(inputDefinition))
                         .defaultValue(buildDefaultValue(inputDefinition.defaultValue))
-                        .type(determineInputType(inputDefinition.type, inputObjects))
+                        .type(determineInputType(inputDefinition.type, inputObjects, referencingInputObjects))
                         .withDirectives(*buildDirectives(inputDefinition.directives, setOf(), Introspection.DirectiveLocation.INPUT_FIELD_DEFINITION))
                 builder.field(fieldBuilder.build())
             }
@@ -297,7 +300,7 @@ class SchemaParser internal constructor(
                 .definition(argumentDefinition)
                 .description(if (argumentDefinition.description != null) argumentDefinition.description.content else getDocumentation(argumentDefinition))
                 .defaultValue(buildDefaultValue(argumentDefinition.defaultValue))
-                .type(determineInputType(argumentDefinition.type, inputObjects))
+                .type(determineInputType(argumentDefinition.type, inputObjects, setOf()))
                 .withDirectives(*buildDirectives(argumentDefinition.directives, setOf(), Introspection.DirectiveLocation.ARGUMENT_DEFINITION))
             field.argument(argumentBuilder.build())
         }
@@ -328,7 +331,7 @@ class SchemaParser internal constructor(
             is NonNullType -> GraphQLNonNull(determineType(expectedType, typeDefinition.type, allowedTypeReferences, inputObjects))
             is InputObjectTypeDefinition -> {
                 log.info("Create input object")
-                createInputObject(typeDefinition, inputObjects)
+                createInputObject(typeDefinition, inputObjects, mutableSetOf())
             }
             is TypeName -> {
                 val scalarType = customScalars[typeDefinition.name]
@@ -346,16 +349,19 @@ class SchemaParser internal constructor(
             else -> throw SchemaError("Unknown type: $typeDefinition")
         }
 
-    private fun determineInputType(typeDefinition: Type<*>, inputObjects: List<GraphQLInputObjectType>) =
-        determineInputType(GraphQLInputType::class, typeDefinition, permittedTypesForInputObject, inputObjects) as GraphQLInputType
+    private fun determineInputType(typeDefinition: Type<*>, inputObjects: List<GraphQLInputObjectType>, referencingInputObjects: Set<String>) =
+        determineInputType(GraphQLInputType::class, typeDefinition, permittedTypesForInputObject, inputObjects, referencingInputObjects) as GraphQLInputType
 
-    private fun <T : Any> determineInputType(expectedType: KClass<T>, typeDefinition: Type<*>, allowedTypeReferences: Set<String>, inputObjects: List<GraphQLInputObjectType>): GraphQLType =
+    private fun <T : Any> determineInputType(expectedType: KClass<T>,
+                                             typeDefinition: Type<*>, allowedTypeReferences: Set<String>,
+                                             inputObjects: List<GraphQLInputObjectType>,
+                                             referencingInputObjects: Set<String>): GraphQLType =
         when (typeDefinition) {
             is ListType -> GraphQLList(determineType(expectedType, typeDefinition.type, allowedTypeReferences, inputObjects))
             is NonNullType -> GraphQLNonNull(determineType(expectedType, typeDefinition.type, allowedTypeReferences, inputObjects))
             is InputObjectTypeDefinition -> {
                 log.info("Create input object")
-                createInputObject(typeDefinition, inputObjects)
+                createInputObject(typeDefinition, inputObjects, referencingInputObjects as MutableSet<String>)
             }
             is TypeName -> {
                 val scalarType = customScalars[typeDefinition.name]
@@ -373,9 +379,14 @@ class SchemaParser internal constructor(
                     } else {
                         val filteredDefinitions = inputObjectDefinitions.filter { it.name == typeDefinition.name }
                         if (filteredDefinitions.isNotEmpty()) {
-                            val inputObject = createInputObject(filteredDefinitions[0], inputObjects)
-                            (inputObjects as MutableList).add(inputObject)
-                            inputObject
+                            val referencingInputObject = referencingInputObjects.find { it == typeDefinition.name }
+                            if (referencingInputObject != null) {
+                                GraphQLTypeReference(referencingInputObject)
+                            } else {
+                                val inputObject = createInputObject(filteredDefinitions[0], inputObjects, referencingInputObjects as MutableSet<String>)
+                                (inputObjects as MutableList).add(inputObject)
+                                inputObject
+                            }
                         } else {
                             // todo: handle enum type
                             GraphQLTypeReference(typeDefinition.name)

src/test/groovy/graphql/kickstart/tools/SchemaParserSpec.groovy

@@ -368,6 +368,50 @@ class SchemaParserSpec extends Specification {
         noExceptionThrown()
     }
 
+    def "allow circular relations in input objects"() {
+        when:
+        SchemaParser.newParser().schemaString('''\
+            input A {
+                id: ID!
+                b: B
+            }
+            input B {
+                id: ID!
+                a: A
+            }
+            input C {
+                id: ID!
+                c: C
+            }
+            type Query {}
+            type Mutation {
+                test(input: A!): Boolean
+                testC(input: C!): Boolean
+            }
+            '''.stripIndent())
+        .resolvers(new GraphQLMutationResolver() {
+            static class A {
+                String id;
+                B b;
+            }
+            static class B {
+                String id;
+                A a;
+            }
+            static class C {
+                String id;
+                C c;
+            }
+            boolean test(A a) { return true }
+            boolean testC(C c) { return true }
+        }, new GraphQLQueryResolver() {})
+        .build()
+        .makeExecutableSchema()
+
+        then:
+        noExceptionThrown()
+    }
+
     enum EnumType {
         TEST
     }