Spring Data Jpa 当属性为Null也更新的解决方案

﹏ヽ暗。殇╰゛Y 2022-11-25 15:28 204阅读 0赞

使用Spring Data Jpa来操作数据库的，可是在更新数据的时候发现一个问题，属性值为Null竟然也更新，这就会导致本来没有更新的属性值，全部就成了Null。

### 实体如下： ###

package com.sgcc.modules.system.domain;
    
    
    import com.fasterxml.jackson.annotation.JsonFormat;
    import com.sgcc.base.BaseEntity;
    import io.swagger.annotations.ApiModelProperty;
    import lombok.Getter;
    import lombok.Setter;
    import org.springframework.format.annotation.DateTimeFormat;
    
    import javax.persistence.*;
    import java.io.Serializable;
    import java.util.Date;
    
    @Entity
    @Getter
    @Setter
    @Table(name = "sys_evaluation_preserve")
    public class EvaluationPreserve extends BaseEntity implements Serializable {
    
      @Id
      @GeneratedValue(strategy = GenerationType.IDENTITY)
      @Column(name = "id")
      @ApiModelProperty(value = "id")
      private Long id;
    
      @Column(name = "assessor_id")
      private String assessorId;
    
      @Column(name = "assessor_name")
      private String assessorName;
    
      @Column(name = "assessor_branch_id")
      private Long assessorBranchId;
    
      @Column(name = "assessor_branch_name")
      private String assessorBranchName;
    
      @Column(name = "assessor_job_id")
      private Long assessorJobId;
    
      @Column(name = "assessor_job_name")
      private String assessorJobName;
    
    
    
    }

### 方案如下： ###

**说明：**

1.  目标源：请求更新的实体数据。
2.  数据源：通过目标源传上来的id，去数据库中查出的实体数据

我们可以将目标源中需要改变的属性值过滤掉以后，将数据源中的数据复制到目标源中，这样就达到了，只是更新需要改变的属性值，不需要更新的保持不变。

import org.springframework.beans.BeanUtils;
    import org.springframework.beans.BeanWrapper;
    import org.springframework.beans.BeanWrapperImpl;
    
    import java.beans.PropertyDescriptor;
    import java.util.HashSet;
    import java.util.Set;
    
    /**
     * There is no royal road to learning.
     * Description:提交实体对象中的null赋值
     * Created by 贤领·周 on 2018年04月10日 15:26
     */
    public class UpdateTool {
        /**
         * 将目标源中不为空的字段过滤，将数据库中查出的数据源复制到提交的目标源中
         *
         * @param source 用id从数据库中查出来的数据源
         * @param target 提交的实体，目标源
         */
        public static void copyNullProperties(Object source, Object target) {
            BeanUtils.copyProperties(source, target, getNoNullProperties(target));
        }
    
        /**
         * @param target 目标源数据
         * @return 将目标源中不为空的字段取出
         */
        private static String[] getNoNullProperties(Object target) {
            BeanWrapper srcBean = new BeanWrapperImpl(target);
            PropertyDescriptor[] pds = srcBean.getPropertyDescriptors();
            Set<String> noEmptyName = new HashSet<>();
            for (PropertyDescriptor p : pds) {
                Object value = srcBean.getPropertyValue(p.getName());
                if (value != null) noEmptyName.add(p.getName());
            }
            String[] result = new String[noEmptyName.size()];
            return noEmptyName.toArray(result);
        }
    }

EvaluationPreserve evaluationPreserve = new EvaluationPreserve();
            evaluationPreserve.setId(evaPreInfoReq.getEvaPreIds().get(0));
            evaluationPreserve.setAssessorName(evaPreInfoReq.getAssessorName());
            evaluationPreserve.setAssessorJobId(evaPreInfoReq.getAssessorJobId());
            evaluationPreserve.setAssessorJobName(evaPreInfoReq.getAssessorJobName());
            evaluationPreserve.setAssessorBranchId(evaPreInfoReq.getAssessorBranchId());
            evaluationPreserve.setAssessorBranchName(evaPreInfoReq.getAssessorBranchName());
    
            EvaluationPreserve evaluationPreserveInfo = evalPreRepository.findById(evaPreInfoReq.getEvaPreIds().get(0)).orElse(new EvaluationPreserve());
            UpdateTool.copyNullProperties(evaluationPreserveInfo,evaluationPreserve);
            EvaluationPreserve save = evalPreRepository.save(evaluationPreserve);
            if(save == null){
                throw new MessageException(ExceptionEnum.UPDATE_OPERATION_FAIL);
            }