NIFI-52: Created new implementation of PreparedQuery so that we can still prepare a query even if the expression is invalid

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

@@ -0,0 +1,71 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.nifi.attribute.expression.language;
+
+import java.util.Map;
+
+import org.apache.nifi.attribute.expression.language.exception.AttributeExpressionLanguageException;
+import org.apache.nifi.expression.AttributeValueDecorator;
+import org.apache.nifi.flowfile.FlowFile;
+import org.apache.nifi.processor.exception.ProcessException;
+
+
+/**
+ * An implementation of PreparedQuery that throws an {@link AttributeExpressionLanguageException} when attempting
+ * to evaluate the query. This allows a PreparedQuery to be created, even though it can't
+ * be evaluated.
+ */
+public class InvalidPreparedQuery implements PreparedQuery {
+    private final String query;
+    private final String explanation;
+    
+    public InvalidPreparedQuery(final String query, final String explanation) {
+        this.query = query;
+        this.explanation = explanation;
+    }
+    
+    @Override
+    public String evaluateExpressions(final FlowFile flowFile, final AttributeValueDecorator decorator) throws ProcessException {
+        throw new AttributeExpressionLanguageException("Invalid Expression: " + query + " due to " + explanation);
+    }
+
+    @Override
+    public String evaluateExpressions() throws ProcessException {
+        throw new AttributeExpressionLanguageException("Invalid Expression: " + query + " due to " + explanation);
+    }
+
+    @Override
+    public String evaluateExpressions(final AttributeValueDecorator decorator) throws ProcessException {
+        throw new AttributeExpressionLanguageException("Invalid Expression: " + query + " due to " + explanation);
+    }
+
+    @Override
+    public String evaluateExpressions(final FlowFile flowFile) throws ProcessException {
+        throw new AttributeExpressionLanguageException("Invalid Expression: " + query + " due to " + explanation);
+    }
+
+    @Override
+    public String evaluateExpressions(final Map<String, String> attributes) throws ProcessException {
+        throw new AttributeExpressionLanguageException("Invalid Expression: " + query + " due to " + explanation);
+    }
+
+    @Override
+    public String evaluateExpressions(final Map<String, String> attributes, final AttributeValueDecorator decorator) throws ProcessException {
+        throw new AttributeExpressionLanguageException("Invalid Expression: " + query + " due to " + explanation);
+    }
+
+}

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

@@ -569,6 +569,7 @@ public class Query {
             return new EmptyPreparedQuery(query.replace("$$", "$"));
         }
 
+        try {
             final List<String> substrings = new ArrayList<>();
             final Map<String, Tree> trees = new HashMap<>();
     
@@ -592,6 +593,9 @@ public class Query {
             }
     
             return new StandardPreparedQuery(substrings, trees);
+        } catch (final AttributeExpressionLanguageParsingException e) {
+            return new InvalidPreparedQuery(query, e.getMessage());
+        }
     }
 
     public static Query compile(final String query) throws AttributeExpressionLanguageParsingException {

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

@@ -17,6 +17,7 @@
 package org.apache.nifi.attribute.expression.language.exception;
 
 public class IllegalAttributeException extends RuntimeException {
+    private static final long serialVersionUID = 12348721897342L;
 
     public IllegalAttributeException() {
         super();