state.js

/*
 * Copyright 2016 BatchIQ
 *
 * Licensed 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.
 */

/******************************************************************************
 * Working with State values in ExecuteScript
 *
 * Variables provided in scope by script engine:
 *
 *     session - ProcessSession
 *     context - ProcessContext
 *     log - ComponentLog
 *     REL_SUCCESS - Relationship
 *     REL_FAILURE - Relationship
 *
 */

flowFile = session.get();
if (flowFile != null) {

    var Scope = Java.type("org.apache.nifi.components.state.Scope");
    var HashMap = Java.type("java.util.HashMap");

    // Get current state
    var oldState = context.getStateManager().getState(Scope.CLUSTER);
    var stateMessage = oldState.get("some-state");

    // Set new state
    var newState = new HashMap();
    newState.put("some-state", stateMessage + "bar");
    context.getStateManager().setState(newState, Scope.CLUSTER);

    session.transfer(flowFile, REL_SUCCESS);
}