com.google.api.server.spi.tools.JacksonUtil.java Source code

Introduction

Here is the source code for com.google.api.server.spi.tools.JacksonUtil.java

Source

/*
 * Copyright 2016 Google Inc. All Rights Reserved.
 *
 * 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.
 */
package com.google.api.server.spi.tools;

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.node.ArrayNode;
import com.fasterxml.jackson.databind.node.ObjectNode;

import java.util.Iterator;

/**
 * Utilities for handling jackson DOM nodes.
 *
 * @author sven@google.com (Sven Mawson)
 */
public class JacksonUtil {

    /**
     * Safely merge two object nodes. This will place any values from the second
     * node into the first if they do not already exist there. The first object
     * is returned as the merged result.
     *
     * @throws IllegalArgumentException if the merge cannot be completed.
     */
    public static ObjectNode mergeObject(ObjectNode object1, ObjectNode object2) {
        return mergeObject(object1, object2, true);
    }

    public static ObjectNode mergeObject(ObjectNode object1, ObjectNode object2, boolean throwOnConflict) {
        Iterator<String> fieldNames = object2.fieldNames();
        while (fieldNames.hasNext()) {
            String fieldName = fieldNames.next();
            JsonNode child2 = object2.get(fieldName);
            JsonNode child1 = object1.get(fieldName);
            JsonNode merged = (child1 == null) ? child2 : mergeNode(child1, child2, throwOnConflict);
            object1.put(fieldName, merged);
        }
        return object1;
    }

    /**
     * Safely merge two array nodes. This will append values from the second
     * array into the first array, and return the first array.
     */
    public static ArrayNode mergeArray(ArrayNode array1, ArrayNode array2) {
        array1.addAll(array2);
        return array1;
    }

    /**
     * Safely merge two nodes. This will appropriately merge objects or lists, as
     * well as verifying that values are compatible if both nodes are values.
     */
    public static JsonNode mergeNode(JsonNode node1, JsonNode node2) {
        return mergeNode(node1, node2, true);
    }

    /**
     * Safely merge two nodes. This will appropriately merge objects or lists, as
     * well as verifying that values are compatible if both nodes are values. If
     * {@code throwOnConflict} is set, an exception will be thrown if there is a merge conflict.
     * Otherwise, node1 will be returned as the conflict resolution.
     */
    public static JsonNode mergeNode(JsonNode node1, JsonNode node2, boolean throwOnConflict) {
        if (node1.isArray()) {
            if (!node2.isArray()) {
                if (throwOnConflict) {
                    throw new IllegalArgumentException("Cannot merge array and non-array: " + node1 + ", " + node2);
                }
                return node1;
            }
            return mergeArray((ArrayNode) node1, (ArrayNode) node2);
        } else if (node1.isObject()) {
            if (!node2.isObject()) {
                if (throwOnConflict) {
                    throw new IllegalArgumentException(
                            "Cannot merge object and non-object: " + node1 + ", " + node2);
                }
                return node1;
            }
            return mergeObject((ObjectNode) node1, (ObjectNode) node2, throwOnConflict);
        } else {
            // Value node, verify equivalence.
            if (throwOnConflict && !node1.equals(node2)) {
                throw new IllegalArgumentException("Cannot merge different values: " + node1 + ", " + node2);
            }
            return node1;
        }
    }
}