Github user bdesert commented on a diff in the pull request:
https://github.com/apache/nifi/pull/2711#discussion_r190296854
--- Diff:
nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/main/java/org/apache/nifi/processors/standard/AttributesToCSV.java
---
@@ -0,0 +1,272 @@
+/*
+ * 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.processors.standard;
+
+import org.apache.commons.lang3.StringEscapeUtils;
+import org.apache.commons.lang3.StringUtils;
+import org.apache.nifi.annotation.behavior.EventDriven;
+import org.apache.nifi.annotation.behavior.SideEffectFree;
+import org.apache.nifi.annotation.behavior.SupportsBatching;
+import org.apache.nifi.annotation.behavior.InputRequirement;
+import org.apache.nifi.annotation.behavior.WritesAttribute;
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.annotation.lifecycle.OnScheduled;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.expression.ExpressionLanguageScope;
+import org.apache.nifi.flowfile.FlowFile;
+import org.apache.nifi.flowfile.attributes.CoreAttributes;
+import org.apache.nifi.processor.AbstractProcessor;
+import org.apache.nifi.processor.ProcessContext;
+import org.apache.nifi.processor.ProcessorInitializationContext;
+import org.apache.nifi.processor.ProcessSession;
+import org.apache.nifi.processor.Relationship;
+import org.apache.nifi.processor.exception.ProcessException;
+import org.apache.nifi.processor.util.StandardValidators;
+
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.List;
+import java.util.ArrayList;
+import java.util.Set;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Collections;
+import java.util.stream.Collectors;
+
+@EventDriven
+@SideEffectFree
+@SupportsBatching
+@Tags({"csv", "attributes", "flowfile"})
+@InputRequirement(InputRequirement.Requirement.INPUT_REQUIRED)
+@CapabilityDescription("Generates a CSV representation of the input
FlowFile Attributes. The resulting CSV " +
+ "can be written to either a newly generated attribute named
'CSVAttributes' or written to the FlowFile as content. " +
+ "If the attribute value contains a comma, newline or double quote,
then the attribute value will be " +
+ "escaped with double quotes. Any double quote characters in the
attribute value are escaped with " +
+ "another double quote. If the attribute value does not contain a
comma, newline or double quote, then the " +
+ "attribute value is returned unchanged.")
+@WritesAttribute(attribute = "CSVAttributes", description = "CSV
representation of Attributes")
--- End diff --
In case a destination is 'content', CSVAttributes won't be written at all
(neither null nor empty string). We could mention that in description.
---
