Github user mattyb149 commented on a diff in the pull request:
https://github.com/apache/nifi/pull/2180#discussion_r159285323
--- Diff:
nifi-nar-bundles/nifi-mongodb-bundle/nifi-mongodb-processors/src/main/java/org/apache/nifi/processors/mongodb/GetMongoAggregation.java
---
@@ -0,0 +1,173 @@
+/*
+ * 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.mongodb;
+
+import com.mongodb.BasicDBObject;
+import com.mongodb.client.AggregateIterable;
+import com.mongodb.client.MongoCollection;
+import com.mongodb.client.MongoCursor;
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.components.ValidationContext;
+import org.apache.nifi.components.ValidationResult;
+import org.apache.nifi.components.Validator;
+import org.apache.nifi.processor.ProcessContext;
+import org.apache.nifi.processor.ProcessSession;
+import org.apache.nifi.processor.Relationship;
+import org.apache.nifi.processor.exception.ProcessException;
+import org.bson.conversions.Bson;
+import org.codehaus.jackson.map.ObjectMapper;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+@Tags({"mongo", "aggregation", "aggregate"})
+@CapabilityDescription("A processor that runs an aggregation query at
user-defined intervals.")
+public class GetMongoAggregation extends AbstractMongoProcessor {
--- End diff --
Without an InputRequirement annotation here, it defaults to INPUT_ALLOWED,
but you are not using any flow file(s) from the session. If you want to
prohibit input, please add a InputRequirement(INPUT_FORBIDDEN) annotation to
the class; otherwise, if you want to use incoming flow files (perhaps as a
trigger or for flow file attributes for the query, for example), you might
consider changing the name (so as not to confuse the behavior with other Get
processors) and checking for an available flow file. Either is fine with me,
unless aggregation queries might be plentiful and different, then I'd tend
toward the input-based approach. If one aggregate query per instance is the
intended use case, then I'm fine with the input-forbidden approach :)
---
