SchemaUtil.java

/*
 * 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
 *
 *   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.streams.util.schema;

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.node.JsonNodeFactory;
import com.fasterxml.jackson.databind.node.ObjectNode;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.net.URL;
import java.util.Iterator;
import java.util.Map;

import static org.apache.commons.lang3.StringUtils.isEmpty;

/**
 * SchemaUtil contains methods to assist in resolving schemas and schema fragments.
 */
public class SchemaUtil {

  private static final Logger LOGGER = LoggerFactory.getLogger(SchemaUtil.class);
  private static final JsonNodeFactory NODE_FACTORY = JsonNodeFactory.instance;
  public static final String ILLEGAL_CHARACTER_REGEX = "[^0-9a-zA-Z_$]";

  public static String childQualifiedName(String parentQualifiedName, String childSimpleName) {
    String safeChildName = childSimpleName.replaceAll(ILLEGAL_CHARACTER_REGEX, "_");
    return isEmpty(parentQualifiedName) ? safeChildName : parentQualifiedName + "." + safeChildName;
  }

  /**
   * read Schema from URL.
   * @param schemaUrl URL
   * @return ObjectNode
   */
  public static ObjectNode readSchema(URL schemaUrl) {

    ObjectNode schemaNode = NODE_FACTORY.objectNode();
    schemaNode.put("$ref", schemaUrl.toString());
    return schemaNode;

  }

  /**
   * merge parent and child properties maps.
   * @param content ObjectNode
   * @param parent ObjectNode
   * @return merged ObjectNode
   */
  public static ObjectNode mergeProperties(ObjectNode content, ObjectNode parent) {

    ObjectNode merged = parent.deepCopy();
    Iterator<Map.Entry<String, JsonNode>> fields = content.fields();
    for ( ; fields.hasNext(); ) {
      Map.Entry<String, JsonNode> field = fields.next();
      String fieldId = field.getKey();
      merged.put(fieldId, field.getValue().deepCopy());
    }
    return merged;
  }

}