Github user markap14 commented on a diff in the pull request: https://github.com/apache/nifi/pull/501#discussion_r66147759 --- Diff: nifi-api/src/main/java/org/apache/nifi/registry/VariableRegistryUtils.java --- @@ -0,0 +1,55 @@ +/* + * 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.registry; + +import java.util.Collections; +import java.util.HashMap; +import java.util.Map; + +import org.apache.nifi.flowfile.FlowFile; + +public class VariableRegistryUtils { + + public static VariableRegistry createVariableRegistry(){ + VariableRegistry variableRegistry = VariableRegistryFactory.getInstance(); + VariableRegistry envRegistry = VariableRegistryFactory.getInstance(System.getenv()); + VariableRegistry propRegistry = VariableRegistryFactory.getInstance(System.getProperties()); + variableRegistry.addRegistry(envRegistry); + variableRegistry.addRegistry(propRegistry); + return variableRegistry; + } + + public static VariableRegistry populateRegistry(VariableRegistry variableRegistry, final FlowFile flowFile, final Map<String, String> additionalAttributes){ + final Map<String, String> flowFileAttributes = flowFile == null ? Collections.<String, String> emptyMap() : flowFile.getAttributes(); + final Map<String, String> additionalOrEmpty = additionalAttributes == null ? Collections.<String, String> emptyMap() : additionalAttributes; + + final Map<String, String> flowFileProps = new HashMap<>(); + if (flowFile != null) { + flowFileProps.put("flowFileId", String.valueOf(flowFile.getId())); + flowFileProps.put("fileSize", String.valueOf(flowFile.getSize())); + flowFileProps.put("entryDate", String.valueOf(flowFile.getEntryDate())); + flowFileProps.put("lineageStartDate", String.valueOf(flowFile.getLineageStartDate())); + } + VariableRegistry newRegistry = VariableRegistryFactory.getInstance(); + newRegistry.addRegistry(variableRegistry); + newRegistry.addRegistry(VariableRegistryFactory.getInstance(flowFileAttributes)); + newRegistry.addRegistry(VariableRegistryFactory.getInstance(additionalOrEmpty)); --- End diff -- I would avoid adding this at all if `additionalAttributes == null`, rather than adding an empty map. Since the EL is used in critical parts of the code we need to avoid any overhead that is not critical. Would suggest the same for `flowFileProps`.
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