JsonClassNameWriter.java

/*
 * Copyright 2018 Global Crop Diversity Trust
 *
 * 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 org.genesys.blocks.util;

import org.genesys.blocks.model.BasicModel;

import com.fasterxml.jackson.annotation.JsonTypeId;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.SerializerProvider;
import com.fasterxml.jackson.databind.cfg.MapperConfig;
import com.fasterxml.jackson.databind.introspect.AnnotatedClass;
import com.fasterxml.jackson.databind.introspect.BeanPropertyDefinition;
import com.fasterxml.jackson.databind.ser.VirtualBeanPropertyWriter;
import com.fasterxml.jackson.databind.util.Annotations;

import lombok.extern.slf4j.Slf4j;

/**
 * The ClassNameWriter is applied to {@link BasicModel} and it instructs Jackson
 * to to include class simple name as a virtual property.
 * 
 * This is so we don't need to rely on {@link JsonTypeId}, which complicates
 * object deserialization.
 * 
 */
@Slf4j
public class JsonClassNameWriter extends VirtualBeanPropertyWriter {

	/** The Constant serialVersionUID. */
	private static final long serialVersionUID = 1L;

	/**
	 * Default constructor.
	 */
	public JsonClassNameWriter() {
		log.trace("JsonClassNameWriter");
	}

	/**
	 * Instantiates a new current permissions writer.
	 *
	 * @param propDef the prop def
	 * @param annotations the annotations
	 * @param type the type
	 */
	public JsonClassNameWriter(BeanPropertyDefinition propDef, Annotations annotations, JavaType type) {
		super(propDef, annotations, type);
		log.trace("JsonClassNameWriter {} annotations: {}", propDef.getName(), annotations);
	}

	/*
	 * (non-Javadoc)
	 * @see
	 * com.fasterxml.jackson.databind.ser.VirtualBeanPropertyWriter#value(java.lang.
	 * Object, com.fasterxml.jackson.core.JsonGenerator,
	 * com.fasterxml.jackson.databind.SerializerProvider)
	 */
	@Override
	protected Object value(Object bean, JsonGenerator gen, SerializerProvider prov) throws Exception {
		log.trace("JsonClassNameWriter.value of {}", bean);
		return bean == null ? null : bean.getClass().getSimpleName();
	}

	/*
	 * (non-Javadoc)
	 * @see
	 * com.fasterxml.jackson.databind.ser.VirtualBeanPropertyWriter#withConfig(com.
	 * fasterxml.jackson.databind.cfg.MapperConfig,
	 * com.fasterxml.jackson.databind.introspect.AnnotatedClass,
	 * com.fasterxml.jackson.databind.introspect.BeanPropertyDefinition,
	 * com.fasterxml.jackson.databind.JavaType)
	 */
	@Override
	public VirtualBeanPropertyWriter withConfig(MapperConfig<?> config, AnnotatedClass declaringClass, BeanPropertyDefinition propDef, JavaType type) {
		log.trace("JsonClassNameWriter.withConfig {}", declaringClass.getName());
		return new JsonClassNameWriter(propDef, declaringClass.getAnnotations(), type);
	}

}