Fix NPE when coercing null enum value in BatchedExecutionStrategy

Author: Antoine Boyer

src/main/java/graphql/execution/batched/BatchedExecutionStrategy.java

@@ -209,7 +209,7 @@ private GraphQLObjectType getGraphQLObjectType(GraphQLType fieldType, Object val
     private void handlePrimitives(List<GraphQLExecutionNodeValue> values, String fieldName,
                                   GraphQLType type) {
         for (GraphQLExecutionNodeValue value : values) {
-            Object coercedValue = coerce(type, value.getValue());
+            Object coercedValue = value.getValue() == null ? null : coerce(type, value.getValue());
             value.getResultContainer().putResult(fieldName, coercedValue);
         }
     }

src/test/groovy/graphql/execution/batched/FunWithStringsSchemaFactory.java

@@ -4,6 +4,7 @@
 import graphql.schema.DataFetcher;
 import graphql.schema.DataFetchingEnvironment;
 import graphql.schema.GraphQLArgument;
+import graphql.schema.GraphQLEnumType;
 import graphql.schema.GraphQLFieldDefinition;
 import graphql.schema.GraphQLList;
 import graphql.schema.GraphQLNonNull;
@@ -290,6 +291,23 @@ GraphQLSchema createSchema() {
 
                 .build();
 
+
+        GraphQLEnumType enumDayType = GraphQLEnumType.newEnum()
+                .name("Day")
+                .value("MONDAY")
+                .value("TUESDAY")
+                .description("Day of the week")
+                .build();
+
+        GraphQLObjectType enumObjectType = GraphQLObjectType.newObject()
+                .name("EnumObject")
+                .field(GraphQLFieldDefinition.newFieldDefinition()
+                       .name("value")
+                       .type(enumDayType)
+                       .dataFetcher(stringObjectValueFetcher)
+                       .build())
+                .build();
+
         GraphQLObjectType queryType = GraphQLObjectType.newObject()
                 .name("StringQuery")
                 .field(GraphQLFieldDefinition.newFieldDefinition()
@@ -304,6 +322,19 @@ GraphQLSchema createSchema() {
                             public Object get(DataFetchingEnvironment env) {return env.getArgument("value");}
                         })
                         .build())
+                .name("EnumQuery")
+                .field(GraphQLFieldDefinition.newFieldDefinition()
+                        .name("enum")
+                        .type(enumObjectType)
+                        .argument(GraphQLArgument.newArgument()
+                             .name("value")
+                             .type(Scalars.GraphQLString)
+                             .build())
+                        .dataFetcher(new DataFetcher() {
+                           @Override
+                           public Object get(DataFetchingEnvironment env) {return env.getArgument("value");}
+                        })
+                        .build())
                 .build();
         return GraphQLSchema.newSchema()
                 .query(queryType)

src/test/groovy/graphql/execution/batched/GraphqlExecutionSpec.groovy

@@ -237,6 +237,20 @@ class GraphqlExecutionSpec extends Specification {
 
     }
 
+    def "Legal null value for enum"() {
+
+        given:
+        String query =
+                "{ enum(value: \"null\") { value } }";
+
+        Map<String, Object> expected = mapOf(
+                "enum", mapOf("value", null));
+
+        expect:
+        runTest(query, expected);
+
+    }
+
     def "Illegal null value for primitives"() {
 
         given: