Merge pull request graphql-java#387 from corydolphin/exception-handling-strategy

bbakerman · web-flow · commit 7bd01a5575a9 · 2017-04-27T12:58:48.000+10:00
Allow ExecutionStrategy to specify dataFetchingExceptionHandler
diff --git a/src/main/java/graphql/execution/ExecutionStrategy.java b/src/main/java/graphql/execution/ExecutionStrategy.java
@@ -43,6 +43,24 @@ public abstract class ExecutionStrategy {
 
     public abstract ExecutionResult execute(ExecutionContext executionContext, ExecutionParameters parameters) throws NonNullableFieldWasNullException;
 
+    /**
+     * Handle exceptions which occur during data fetching. By default, add all exceptions to the execution context's
+     * error's. Subclasses may specify custom handling, e.g. of different behavior with different exception types (e.g.
+     * re-throwing certain exceptions).
+     * @param executionContext
+     * @param fieldDef
+     * @param argumentValues
+     * @param e
+     */
+    protected void handleDataFetchingException(
+            ExecutionContext executionContext,
+            GraphQLFieldDefinition fieldDef,
+            Map<String, Object> argumentValues,
+            Exception e) {
+        executionContext.addError(new ExceptionWhileDataFetching(e));
+    }
+
+
     protected ExecutionResult resolveField(ExecutionContext executionContext, ExecutionParameters parameters, List<Field> fields) {
         GraphQLObjectType type = parameters.typeInfo().castType(GraphQLObjectType.class);
         GraphQLFieldDefinition fieldDef = getFieldDef(executionContext.getGraphQLSchema(), type, fields.get(0));
@@ -70,8 +88,7 @@ protected ExecutionResult resolveField(ExecutionContext executionContext, Execut
             fetchCtx.onEnd(resolvedValue);
         } catch (Exception e) {
             log.warn("Exception while fetching data", e);
-            executionContext.addError(new ExceptionWhileDataFetching(e));
-
+            handleDataFetchingException(executionContext, fieldDef, argumentValues, e);
             fetchCtx.onEnd(e);
         }
 
diff --git a/src/main/java/graphql/execution/batched/BatchedExecutionStrategy.java b/src/main/java/graphql/execution/batched/BatchedExecutionStrategy.java
@@ -1,6 +1,5 @@
 package graphql.execution.batched;
 
-import graphql.ExceptionWhileDataFetching;
 import graphql.ExecutionResult;
 import graphql.ExecutionResultImpl;
 import graphql.GraphQLException;
@@ -267,12 +266,9 @@ private List<GraphQLExecutionNodeValue> fetchData(ExecutionContext executionCont
         try {
             values = (List<Object>) getDataFetcher(fieldDef).get(environment);
         } catch (Exception e) {
-            values = new ArrayList<>();
-            for (int i = 0; i < nodeData.size(); i++) {
-                values.add(null);
-            }
+            values = new ArrayList<>(nodeData.size());
             log.warn("Exception while fetching data", e);
-            executionContext.addError(new ExceptionWhileDataFetching(e));
+            handleDataFetchingException(executionContext, fieldDef, argumentValues, e);
         }
         assert nodeData.size() == values.size();
 
