NIFI-625: Fixed bug in expression language that caused EL not to get evaluated if enclosed within curly braces

nifi/nifi-commons/nifi-expression-language/src/main/java/org/apache/nifi/attribute/expression/language/Query.java

@@ -264,7 +264,14 @@ public class Query {
                         }
                     }
 
+                    // Keep track of the number of opening curly braces that we are embedded within,
+                    // if we are within an Expression. If we are outside of an Expression, we can just ignore
+                    // curly braces. This allows us to ignore the first character if the value is something
+                    // like: { ${abc} }
+                    // However, we will count the curly braces if we have something like: ${ $${abc} }
+                    if (expressionStart > -1) {
                         embeddedCount++;
+                    }
                 } else if (c == '}') {
                     if (embeddedCount <= 0) {
                         continue;
@@ -965,7 +972,7 @@ public class Query {
             case NUMBER:
                 return (NumberEvaluator) evaluator;
             case STRING:
-                return new NumberCastEvaluator((StringEvaluator) evaluator);
+                return new NumberCastEvaluator(evaluator);
             case DATE:
                 return new DateToNumberEvaluator((DateEvaluator) evaluator);
             default:

nifi/nifi-commons/nifi-expression-language/src/test/java/org/apache/nifi/attribute/expression/language/TestQuery.java

@@ -361,6 +361,8 @@ public class TestQuery {
 
     @Test
     public void testExtractExpressionRanges() {
+        assertEquals(29, Query.extractExpressionRanges("${hello:equals( $${goodbye} )}").get(0).getEnd());
+
         List<Range> ranges = Query.extractExpressionRanges("hello");
         assertTrue(ranges.isEmpty());
 
@@ -1098,6 +1100,18 @@ public class TestQuery {
         verifyEquals(query, attributes, true);
     }
 
+    @Test
+    public void testEvaluateWithinCurlyBraces() {
+        final Map<String, String> attributes = new HashMap<>();
+        attributes.put("abc", "xyz");
+
+        final String query = "{ ${abc} }";
+        final List<String> expressions = Query.extractExpressions(query);
+        assertEquals(1, expressions.size());
+        assertEquals("${abc}", expressions.get(0));
+        assertEquals("{ xyz }", Query.evaluateExpressions(query, attributes));
+    }
+
     private void verifyEquals(final String expression, final Map<String, String> attributes, final Object expectedResult) {
         Query.validateExpression(expression, false);
         assertEquals(String.valueOf(expectedResult), Query.evaluateExpressions(expression, attributes, null));

nifi/nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/test/java/org/apache/nifi/processors/standard/TestReplaceText.java

@@ -368,4 +368,22 @@ public class TestReplaceText {
         System.out.println(outContent);
     }
 
+    @Test
+    public void testReplaceWithinCurlyBraces() throws IOException {
+        final TestRunner runner = TestRunners.newTestRunner(new ReplaceText());
+        runner.setValidateExpressionUsage(false);
+        runner.setProperty(ReplaceText.REGEX, ".+");
+        runner.setProperty(ReplaceText.REPLACEMENT_VALUE, "{ ${filename} }");
+
+        final Map<String, String> attributes = new HashMap<>();
+        attributes.put("filename", "abc.txt");
+        runner.enqueue("Hello".getBytes(), attributes);
+
+        runner.run();
+
+        runner.assertAllFlowFilesTransferred(ReplaceText.REL_SUCCESS, 1);
+        final MockFlowFile out = runner.getFlowFilesForRelationship(ReplaceText.REL_SUCCESS).get(0);
+        out.assertContentEquals("{ abc.txt }");
+    }
+
 }