Added support for deserialising Optional collection types

Author: Mridang Agarwalla

gradle/wrapper/gradle-wrapper.properties

@@ -1,5 +1,6 @@
+#Mon Nov 30 23:20:00 EET 2020
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.5.1-all.zip
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-6.5.1-bin.zip
-zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
+zipStoreBase=GRADLE_USER_HOME

src/main/java/graphql/annotations/dataFetchers/MethodDataFetcher.java

@@ -131,6 +131,7 @@ private Object[] invocationArgs(DataFetchingEnvironment environment, ProcessingE
         return result.toArray();
     }
 
+    @SuppressWarnings("ConstantConditions")
     private Object buildArg(Type p, GraphQLType graphQLType, Optional<Object> arg) {
         if (arg == null) {
             return null;
@@ -140,7 +141,7 @@ private Object buildArg(Type p, GraphQLType graphQLType, Optional<Object> arg) {
         }
 
         if (p instanceof Class<?> && graphQLType instanceof GraphQLInputObjectType) {
-            Constructor<?> constructors[] = ((Class) p).getConstructors();
+            Constructor<?>[] constructors = ((Class) p).getConstructors();
             Constructor<?> constructor = getBuildArgConstructor(constructors);
             Parameter[] parameters = constructor.getParameters();
 
@@ -156,15 +157,23 @@ private Object buildArg(Type p, GraphQLType graphQLType, Optional<Object> arg) {
                 return constructNewInstance(constructor, objects.toArray(new Object[objects.size()]));
             }
         } else if (p instanceof ParameterizedType && graphQLType instanceof GraphQLList) {
-            List<Object> list = new ArrayList<>();
-            Type subType = ((ParameterizedType) p).getActualTypeArguments()[0];
-            GraphQLType wrappedType = ((GraphQLList) graphQLType).getWrappedType();
+            if (((ParameterizedType) p).getRawType() == Optional.class) {
+                if (arg == null) {
+                    return null;
+                } else {
+                    Type subType = ((ParameterizedType) p).getActualTypeArguments()[0];
+                    return Optional.ofNullable(buildArg(subType, graphQLType, arg));
+                }
+            } else {
+                List<Object> list = new ArrayList<>();
+                Type subType = ((ParameterizedType) p).getActualTypeArguments()[0];
+                GraphQLType wrappedType = ((GraphQLList) graphQLType).getWrappedType();
 
-            for (Object item : ((List) arg.get())) {
-                list.add(buildArg(subType, wrappedType, Optional.ofNullable(item)));
+                for (Object item : ((List) arg.get())) {
+                    list.add(buildArg(subType, wrappedType, Optional.ofNullable(item)));
+                }
+                return list;
             }
-
-            return list;
         } else if (p instanceof ParameterizedType && ((ParameterizedType) p).getRawType() == Optional.class) {
             Type subType = ((ParameterizedType) p).getActualTypeArguments()[0];
             if (arg == null) {

src/test/java/graphql/annotations/GraphQLInputTest.java

@@ -169,6 +169,12 @@ public String something(@GraphQLName("code") AnotherCode code) {
         public String otherthing(@GraphQLName("code") AnotherCode code) {
             return (code.firstField != null ? code.firstField.orElse("") : "") + code.secondField;
         }
+
+        @SuppressWarnings({"unused", "OptionalAssignedToNull", "OptionalUsedAsFieldOrParameterType"})
+        @GraphQLField
+        public String listthings(@GraphQLName("codes") Optional<List<AnotherCode>> code) {
+            return code == null ? "was null" : (code.map(anotherCodes -> "code was " + anotherCodes.size()).orElse("was empty"));
+        }
     }
 
     public static class QueryMultipleDefinitions {
@@ -232,10 +238,11 @@ public void queryWithUndefinableParameters() {
         GraphQLSchema schema = newAnnotationsSchema().query(QueryUndefinedParameter.class).build();
 
         GraphQL graphQL = GraphQL.newGraphQL(schema).build();
-        ExecutionResult result = graphQL.execute("{ something(code: {firstField:\"a\",secondField:\"b\"}) otherthing(code: {secondField:\"c\"})  }", new QueryUndefinedParameter());
+        ExecutionResult result = graphQL.execute("{ something(code: {firstField:\"a\",secondField:\"b\"}) otherthing(code: {secondField:\"c\"}) listthings  }", new QueryUndefinedParameter());
         assertTrue(result.getErrors().isEmpty());
         assertEquals(((Map<String, String>) result.getData()).get("something"), "ab");
         assertEquals(((Map<String, String>) result.getData()).get("otherthing"), "c");
+        assertEquals(((Map<String, String>) result.getData()).get("listthings"), "was null");
     }
 
     @Test