[PostgreSQL] Ver tabernus Mybatis-plus PostgreSQL handles json type situations

2024-07-12

Tabernus ver + Mybatis-plus + PostgreSQL tractat json generis condiciones

I. Introductio
2. Technology acervus
3. Background analysis
4. Programma analysis
- 4.1 Directe reponunt json res in PostgreSQL database
- 4.2 Repono json chordas in PostgreSQL database
5. Custom genus processus
- 5.1 Definiens genus tracto
- 5.2 Using mos genus processors

I. Introductio

In Springboot project evolutionis, database relativa plerumque adhibetur ut datorum principalium ad reponendas notitias. Aliquando negotiationes missionum necessarias extendere consuetudinarias notitias in structura mensae exsistentis. In hoc missione, json genus repositionis generaliter adhibetur. Articulus hic summat solutionem practicam ad operandum json in Springboot project ope Mybatis-plus.

2. Technology acervus

Ver tabernus + Mybatis-plus + PostgreSQL, campus quidam in database PostgreSQL generis json est.

Insert imaginem descriptionis hic

3. Background analysis

In MyBatis, tracto typus (TypeHandler) partes pontis agit inter JavaType et JdbcType. Solent dare valorem obiecti Javae ad praeparationem praeparationis cum enuntiationem SQL exequens vel valorem ex ResultSet vel CallableStatement recuperare.

MyBatis-Plus tibi praebet cum processoribus quibusdam constructis-in specie, quod esse potest TableField Annotationes in MyBatis receptaculo cito injiciuntur, processus evolutionis simpliciores. MyBatis-Plus agri genus processus officialis referat documentum:Field type processor |

JSON genus agri tracto

MyBatis-Plus varias habet processus in JSON genus processuum constructum, comprehendo AbstractJsonTypeHandler atque subcategoriisFastjson2TypeHandler、FastjsonTypeHandler、GsonTypeHandler、JacksonTypeHandler manere. Processores hi possunt chordas JSON convertere et ab obiectis Java.

4. Programma analysis

4.1 Directe reponunt json res in PostgreSQL database

Agri database PostgreSQL monstrantur in figura supra: param_config est genus agri json.

Gradus I scribentes entia

Ager notitia genus est com.alibaba.fastjson2.JSONObject 。

@Data
@Accessors(chain = true)
@TableName(autoResultMap = true)
public class User {
    
    private Long id;

    ...

    /**
   	 * 关键代码！！！
     * 必须开启映射注解
     *
     * @TableName(autoResultMap = true)
     *
     * 选择对应的 JSON 处理器，并确保存在对应的 JSON 解析依赖包
     */
    @TableField(value = "param_config", typeHandler = JacksonTypeHandler.class)
    // 或者使用 FastjsonTypeHandler
    // @TableField(typeHandler = FastjsonTypeHandler.class)
    private JSONObject paramConfig;
}
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Gradus 2: XML configuratione respondentem scribendi methodum

<!-- 关键代码！！！！！！！ -->
<!-- 单个字段的类型处理器配置 -->
<result column="param_config" jdbcType="VARCHAR" property="paramConfig" typeHandler="com.baomidou.mybatisplus.extension.handlers.JacksonTypeHandler" />

<!-- 多个字段中某个字段的类型处理器配置 -->
<resultMap id="departmentResultMap" type="com.baomidou...DepartmentVO">
    <result property="director" column="director" typeHandler="com.baomidou.mybatisplus.extension.handlers.JacksonTypeHandler" />
</resultMap>
<select id="selectPageVO" resultMap="departmentResultMap">
   select id,name,director from department ...
</select>
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Videre eventus qui salvantur in database, ut infra ostendemus:

Insert imaginem descriptionis hic

4.2 Repono json chordas in PostgreSQL database

Primum adde post PostgreSQL database URL & Stringtype = non specificataenota quod si haec figuratio nomine datorum directe praecedit, debes & Restituo cum? 。

Gradus I scribens aliquid genus

@TableField(value = "param_config", typeHandler = JacksonTypeHandler.class)
private String paramConfig;
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Gradus 2: XML configuratione respondentem scribendi methodum

<!-- 单个字段的类型处理器配置 -->
<result column="param_config" jdbcType="VARCHAR" property="paramConfig" typeHandler="com.baomidou.mybatisplus.extension.handlers.JacksonTypeHandler" />
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Videre eventus qui salvantur in database, ut infra ostendemus:

Insert imaginem descriptionis hic

5. Custom genus processus

In MyBatis-Plus, praeterquam utens processus typum constructum-, tincturae quoque genus processores mos est ut opus sit.

Exempli gratia, cum usura datorum PostgreSQL, campos generis JSON occurrere potes. In hoc casu, morem genus processus facere potes ad processum JSON datae.

5.1 Definiens genus tracto

Exemplum consuetudinis JSON processoris typus est:

package com.ruoyi.common.utils.pg;

import com.ruoyi.common.utils.StringUtils;
import org.apache.ibatis.type.BaseTypeHandler;
import org.apache.ibatis.type.JdbcType;
import org.apache.ibatis.type.MappedTypes;
import org.postgresql.util.PGobject;

import java.sql.CallableStatement;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

/**
 * @ClassName: JsonTypeHandlerPg
 * @Description: json对象处理
 * @Author: hjm
 * @Date: 2024-07-11 10:34
 */
@MappedTypes(String.class)
public class JsonTypeHandlerPg extends BaseTypeHandler<String> {

    /**
     * 引入PGSQL提供的工具类PGobject
     */
    private static final PGobject JSON_OBJECT = new PGobject();
    public static final String JSON_TYPE = "json";

    /**
     * 关键位置!!!
     */
    @Override
    public void setNonNullParameter(PreparedStatement ps, int i, String param, JdbcType jdbcType) throws SQLException {
        JSON_OBJECT.setType(JSON_TYPE);
        JSON_OBJECT.setValue(param);
        ps.setObject(i, JSON_OBJECT);
    }

    @Override
    public String getNullableResult(ResultSet rs, String columnName) throws SQLException {
        String sqlJson = rs.getString(columnName);
        if (StringUtils.isNotBlank(sqlJson)) {
            return sqlJson;
        }
        return null;
    }

    // 根据列索引，获取可以为空的结果
    @Override
    public String getNullableResult(ResultSet rs, int columnIndex) throws SQLException {
        String sqlJson = rs.getString(columnIndex);
        if (StringUtils.isNotBlank(sqlJson)) {
            return sqlJson;
        }
        return null;
    }

    @Override
    public String getNullableResult(CallableStatement cs, int columnIndex) throws SQLException {
        String sqlJson = cs.getString(columnIndex);
        if (StringUtils.isNotBlank(sqlJson)) {
            return sqlJson;
        }
        return null;
    }
}
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5.2 Using mos genus processors

In genere entitatis, pass TableField Annotationes specificare consuetudinis genus tracto:

/**
 * 测试对象
 *
 * @author hjm
 * @date 2024-07-11
 */
@Data
@EqualsAndHashCode(callSuper = true)
@TableName("data_test")
public class DataTest extends BaseEntity {

    private static final long serialVersionUID = 1L;

    /**
     * 主键
     */
    @TableId(value = "id")
    private Long id;
    
    /**
     * 关键位置!!!
     */
    @TableField(typeHandler = JsonTypeHandlerPg.class)
    private String jsonData;
}
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Mutare mapper file

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
    PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
    "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.ruoyi.dt.mapper.DataTestMapper">

    <resultMap type="com.ruoyi.dt.domain.DataTest" id="DataTestResult">
        <result property="id" column="id"/>
		<!-- 关键位置!!! -->
        <result property="jsonData" column="json_data" typeHandler="com.ruoyi.common.utils.pg.JsonTypeHandlerPg"/>
        <result property="createBy" column="create_by"/>
        <result property="createTime" column="create_time"/>
        <result property="updateBy" column="update_by"/>
        <result property="updateTime" column="update_time"/>
    </resultMap>

</mapper>
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Negotium codice

    /**
     * 新增数据
     */
    @Override
    public Boolean insertByAo(DataTestAo ao) {
        DataTest add = BeanUtil.toBean(ao, DataTest.class);
        // 关键位置!!!
		add.setJsonData(JSONUtil.toJsonStr(ao));
        validEntityBeforeSave(add);
        boolean flag = baseMapper.insert(add) > 0;
        if (flag) {
            ao.setId(add.getId());
        }
        return flag;
    }

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Articulus hic finitur!

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