refactoring and null pointer fix

refactoring and fix null pointer exception in history extraction

Author: vasile-baluta

src/main/java/com/ericsson/ei/handlers/UpStreamEventsHandler.java

@@ -55,7 +55,7 @@ public void setHistoryExtractionHandler(final HistoryExtractionHandler historyEx
      * Run history extraction rules on all upstream events.
      *
      * @param aggregatedObjectId
-     *            the aggregated object id
+     *                               the aggregated object id
      */
     public void runHistoryExtractionRulesOnAllUpstreamEvents(String aggregatedObjectId) {
 
@@ -98,26 +98,29 @@ public void runHistoryExtractionRulesOnAllUpstreamEvents(String aggregatedObject
      * </pre>
      *
      * @param jsonArray
-     *            the array to traverse
+     *                                   the array to traverse
      * @param aggregatedObjectId
-     *            the id of the aggregated object
+     *                                   the id of the aggregated object
      * @param pathInAggregatedObject
-     *            the current path in the aggregated object
+     *                                   the current path in the aggregated object
      */
     private void traverseTree(final JsonNode jsonArray, final String aggregatedObjectId,
             final String pathInAggregatedObject) {
 
-        final JsonNode parent = jsonArray.get(0);
-        JsonNode parentId = parent.at("/meta/id");
         String np = pathInAggregatedObject;
-        if (!aggregatedObjectId.equals(parentId.textValue())) {
-            // parent event is not the same as the starting event so we can
-            // start collecting history
-            RulesObject rules = rulesHandler.getRulesForEvent(parent.toString());
-
-            np = historyExtractionHandler.runHistoryExtraction(aggregatedObjectId, rules, parent.toString(),
-                    pathInAggregatedObject);
+        final JsonNode parent = jsonArray.get(0);
+        if (parent != null) {
+            JsonNode parentId = parent.at("/meta/id");
+            if (!aggregatedObjectId.equals(parentId.textValue())) {
+                // parent event is not the same as the starting event so we can
+                // start collecting history
+                RulesObject rules = rulesHandler.getRulesForEvent(parent.toString());
+
+                np = historyExtractionHandler.runHistoryExtraction(aggregatedObjectId, rules, parent.toString(),
+                        pathInAggregatedObject);
+            }
         }
+
         String prevNp = null;
         for (int i = 1; i < jsonArray.size(); i++) {
             if (jsonArray.get(i).isObject()) {

src/main/java/com/ericsson/ei/jmespath/JmesPathInterface.java

@@ -48,18 +48,21 @@ public JmesPathInterface() {
         jmespath = new JacksonRuntime(customFunctions);
     }
 
-    public JsonNode runRuleOnEvent(String rule, String input) {
-        JsonNode event = null;
-        if (input == null) {
-            input = "";
+    public JsonNode runRuleOnEvent(String rule, String event) {
+        JsonNode result = JsonNodeFactory.instance.nullNode();
+        String inputs[] = { rule, event };
+        for (String input : inputs) {
+            if (input == null || input == "") {
+                return result;
+            }
         }
 
         ObjectMapper objectMapper = new ObjectMapper();
-        JsonNode result = JsonNodeFactory.instance.nullNode();
+
         try {
             Expression<JsonNode> expression = jmespath.compile(rule);
-            event = objectMapper.readValue(input, JsonNode.class);
-            result = expression.search(event);
+            JsonNode eventJson = objectMapper.readValue(event, JsonNode.class);
+            result = expression.search(eventJson);
         } catch (Exception e) {
             log.info(e.getMessage(), e);
         }

src/test/java/com/ericsson/ei/jmespath/test/TestJmesPathInterface.java

@@ -98,4 +98,13 @@ public void testJsonNodeEmpty() throws Exception {
 
         int wait = 0;
     }
+
+    @Test
+    public void testEmptyInputs() throws Exception {
+        JsonNode result1 = unitUnderTest.runRuleOnEvent("", "");
+        JsonNode result2 = unitUnderTest.runRuleOnEvent("", "{\"test\" :\"test\"}");
+        JsonNode result3 = unitUnderTest.runRuleOnEvent("{\"test\" :\"test\"}", "");
+
+        boolean wait = true;
+    }
 }