MyBatisBindTagProcessor.java

/*
 *    Copyright 2018-2022 the original author or authors.
 *
 *    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
 *
 *       https://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.mybatis.scripting.thymeleaf.processor;

import java.util.List;
import java.util.Objects;

import org.mybatis.scripting.thymeleaf.MyBatisBindingContext;
import org.thymeleaf.context.ITemplateContext;
import org.thymeleaf.engine.AttributeName;
import org.thymeleaf.exceptions.TemplateProcessingException;
import org.thymeleaf.model.IProcessableElementTag;
import org.thymeleaf.processor.element.AbstractAttributeTagProcessor;
import org.thymeleaf.processor.element.IElementTagStructureHandler;
import org.thymeleaf.standard.expression.Assignation;
import org.thymeleaf.standard.expression.AssignationSequence;
import org.thymeleaf.standard.expression.AssignationUtils;
import org.thymeleaf.standard.expression.IStandardExpression;
import org.thymeleaf.templatemode.TemplateMode;
import org.thymeleaf.util.StringUtils;

/**
 * The processor class for handling the {@code mybatis:bind} tag. <br>
 * This processor register an any value to the MyBatis’s bind variables (similar to that of the {@code <bind>} provided
 * by MyBatis core module) This class's implementation was inspired with the {@code StandardWithTagProcessor} provide by
 * Thymeleaf.
 *
 * @author Kazuki Shimizu
 *
 * @version 1.0.0
 *
 * @see org.thymeleaf.standard.processor.StandardWithTagProcessor
 */
public class MyBatisBindTagProcessor extends AbstractAttributeTagProcessor {

  private static final int PRECEDENCE = 600;
  private static final String ATTR_NAME = "bind";

  /**
   * Constructor that can be specified the template mode and dialect prefix.
   *
   * @param templateMode
   *          A target template mode
   * @param prefix
   *          A target dialect prefix
   */
  public MyBatisBindTagProcessor(final TemplateMode templateMode, final String prefix) {
    super(templateMode, prefix, null, false, ATTR_NAME, true, PRECEDENCE, true);
  }

  /**
   * {@inheritDoc}
   */
  @Override
  protected void doProcess(ITemplateContext context, IProcessableElementTag tag, AttributeName attributeName,
      String attributeValue, IElementTagStructureHandler structureHandler) {
    AssignationSequence assignations = AssignationUtils.parseAssignationSequence(context, attributeValue, false);

    List<Assignation> assignationValues = assignations.getAssignations();
    assignationValues.forEach(assignation -> {
      IStandardExpression nameExp = assignation.getLeft();
      Object name = nameExp.execute(context);
      IStandardExpression valueExp = assignation.getRight();
      Object value = valueExp.execute(context);

      if (Objects.isNull(name) || StringUtils.isEmpty(name.toString())) {
        throw new TemplateProcessingException(
            "Variable name expression evaluated as null or empty: \"" + nameExp + "\"");
      }

      MyBatisBindingContext bindingContext = MyBatisBindingContext.load(context);
      bindingContext.setCustomBindVariable(name.toString(), value);
    });
  }

}