Convert non nullable exception to graphql error for subscription

Author: oliemansm

graphql-java-kickstart/src/main/java/graphql/kickstart/execution/subscriptions/SessionSubscriber.java

@@ -1,13 +1,13 @@
 package graphql.kickstart.execution.subscriptions;
 
-import graphql.ExecutionResult;
+import static java.util.Collections.singletonList;
 
-import java.util.Collections;
+import graphql.ExecutionResult;
+import graphql.GraphqlErrorBuilder;
+import graphql.execution.NonNullableFieldWasNullException;
+import graphql.kickstart.execution.error.GenericGraphQLError;
 import java.util.HashMap;
 import java.util.Map;
-
-import graphql.GraphQLError;
-import graphql.kickstart.execution.error.GenericGraphQLError;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 import org.reactivestreams.Subscriber;
@@ -42,9 +42,17 @@ public void onNext(ExecutionResult executionResult) {
   @Override
   public void onError(Throwable throwable) {
     log.error("Subscription error", throwable);
-
     Map<String, Object> payload = new HashMap<>();
-    payload.put("errors", Collections.singletonList(new GenericGraphQLError(throwable.getMessage())));
+    if (throwable.getCause() instanceof NonNullableFieldWasNullException) {
+      NonNullableFieldWasNullException e = (NonNullableFieldWasNullException) throwable.getCause();
+      payload.put("errors", singletonList(GraphqlErrorBuilder.newError()
+          .message(e.getMessage())
+          .path(e.getPath())
+          .build()));
+    } else {
+      payload
+          .put("errors", singletonList(new GenericGraphQLError(throwable.getMessage())));
+    }
 
     session.unsubscribe(id);
     session.sendErrorMessage(id, payload);

graphql-java-servlet/src/main/java/graphql/kickstart/servlet/GraphQLConfiguration.java

@@ -24,7 +24,6 @@ public class GraphQLConfiguration {
 
   private final GraphQLInvocationInputFactory invocationInputFactory;
   private final Supplier<BatchInputPreProcessor> batchInputPreProcessor;
-  private final GraphQLQueryInvoker queryInvoker;
   private final GraphQLInvoker graphQLInvoker;
   private final GraphQLObjectMapper objectMapper;
   private final List<GraphQLServletListener> listeners;
@@ -43,7 +42,6 @@ private GraphQLConfiguration(GraphQLInvocationInputFactory invocationInputFactor
       Supplier<BatchInputPreProcessor> batchInputPreProcessor,
       GraphQLResponseCacheManager responseCacheManager) {
     this.invocationInputFactory = invocationInputFactory;
-    this.queryInvoker = queryInvoker;
     this.graphQLInvoker = queryInvoker.toGraphQLInvoker();
     this.objectMapper = objectMapper;
     this.listeners = listeners;
@@ -71,10 +69,6 @@ public GraphQLInvocationInputFactory getInvocationInputFactory() {
     return invocationInputFactory;
   }
 
-  public GraphQLQueryInvoker getQueryInvoker() {
-    return queryInvoker;
-  }
-
   public GraphQLInvoker getGraphQLInvoker() {
     return graphQLInvoker;
   }
@@ -113,15 +107,19 @@ public GraphQLResponseCacheManager getResponseCacheManager() {
 
   public HttpRequestHandler getHttpRequestHandler() {
     if (requestHandler == null) {
-      if (responseCacheManager == null) {
-        requestHandler = new HttpRequestHandlerImpl(this);
-      } else {
-        requestHandler = new HttpRequestHandlerImpl(this, new CachingHttpRequestInvoker(this));
-      }
+      requestHandler = createHttpRequestHandler();
     }
     return requestHandler;
   }
 
+  private HttpRequestHandler createHttpRequestHandler() {
+    if (responseCacheManager == null) {
+      return new HttpRequestHandlerImpl(this);
+    } else {
+      return new HttpRequestHandlerImpl(this, new CachingHttpRequestInvoker(this));
+    }
+  }
+
   public static class Builder {
 
     private GraphQLInvocationInputFactory.Builder invocationInputFactoryBuilder;