diff --git a/nop-graphql/nop-graphql-core/src/main/java/io/nop/graphql/core/engine/GraphQLEngine.java b/nop-graphql/nop-graphql-core/src/main/java/io/nop/graphql/core/engine/GraphQLEngine.java
index b1b5e7d34..c9f8a703b 100644
--- a/nop-graphql/nop-graphql-core/src/main/java/io/nop/graphql/core/engine/GraphQLEngine.java
+++ b/nop-graphql/nop-graphql-core/src/main/java/io/nop/graphql/core/engine/GraphQLEngine.java
@@ -326,8 +326,7 @@ public void initGraphQLContext(IGraphQLExecutionContext context, ParsedGraphQLRe
         }
         validateDocument(doc);
 
-        Map<String, Object> vars = request.getVariables();
-        GraphQLOperation op = (GraphQLOperation) doc.getDefinitions().get(0);
+        GraphQLOperation op = doc.getOperation();
         if (op.getSelectionSet() == null || op.getSelectionSet().isEmpty())
             throw new NopException(ERR_GRAPHQL_QUERY_NO_OPERATION);
 
@@ -337,6 +336,8 @@ public void initGraphQLContext(IGraphQLExecutionContext context, ParsedGraphQLRe
 
         context.setOperation(op);
         context.setExecutionId(request.getOperationId());
+
+        Map<String, Object> vars = request.getVariables();
         FieldSelectionBean selectionBean = buildSelectionBean(op.getName(), op.getSelectionSet(), vars);
         context.setFieldSelection(selectionBean);
     }
@@ -560,4 +561,4 @@ public CompletionStage<Object> fetchResult(Object result, IGraphQLExecutionConte
         IGraphQLExecutor executor = new GraphQLExecutor(operationInvoker, graphQLHook, flowControlRunner, this);
         return executor.fetchResult(result, context);
     }
-}
\ No newline at end of file
+}