Mybatis plus about the operation of JSON fields in MYSQL

First of all, the JSON field is applicable only in Sql5.7+. When you use it, you must pay attention to your MySql version!!!

1. Mysql related fields

2. JSON content inserted in related fields

3. Modify the corresponding entity class

The two fields related to us in content 3 are JSON types in mysql. For our convenience, we can customize the encapsulation object to receive and pass our JSON fields. The following two fields share a type of encapsulated object, as follows: premaritalandpremaritaninfo. Here we can write a static class to encapsulate under the current entity class, or write a separate class to encapsulate.

In the entity class we are concerned about, there are two attributes in the annotation that we are concerned about:
@TableName(value = "t_ppaal",autoResultMap = true)
autoResultMap = true: automatically match the mapping of resultmap in our mapper.xml.

@TableField(value = "premarital", typeHandler = JacksonTypeHandler.class)
typeHandler = JacksonTypeHandler.class: because this is the field receiving of Json type, we add a TypeHandler of Json type, which is the field handler in MybatisPlus. We can use it to deal with entity class attributes and table fields.

@Data
@EqualsAndHashCode(callSuper = true)
@AllArgsConstructor
@NoArgsConstructor
@TableName(value = "t_ppaal",autoResultMap = true)
public class Ppaal extends BaseEntity implements Serializable {
	/**
	/**
	 * Classification of diseases detected before marriage HQ003
	 */
	@TableField(value = "premarital", typeHandler = JacksonTypeHandler.class)
	@ApiModelProperty(value = "Classification of diseases detected before marriage HQ003")
	private PremaritalAndPremaritalInfo premarital;

	/**
	 * Pre pregnancy risk factors HQ004
	 */
	@TableField(value = "progestation", typeHandler = JacksonTypeHandler.class)
	@ApiModelProperty(value = "Pre pregnancy risk factors HQ004")
	private PremaritalAndPremaritalInfo progestation;
	/**
	 * Encapsulation of json fields
	 */
	@Data
	public static class PremaritalAndPremaritalInfo implements Serializable {
		private List<String> woman;
		private List<String> man;
	}
}

4. Modify the corresponding mapper.xml

What needs to be modified here are jdbcType, typeHandler and javaType. If not, just add it
First, modify the corresponding typeHandler, which is the same as that in the entity class.
Set the javatype. The javatype is the entity we encapsulated. Because it is encapsulated inside the entity, it can be defined with the $symbol
jdbcType, because there is no corresponding Json type in jdbcType. So we customize the object that receives Json type. Because it is java language, we define jdbcType as JAVA_OBJECT.

<result column="premarital" jdbcType="JAVA_OBJECT" property="premarital"
typeHandler="com.baomidou.mybatisplus.extension.handlers.JacksonTypeHandler"
javaType="com.esmooc.life.marriage.entity.Ppaal$PremaritalAndPremaritalInfo"/>

<result column="progestation" jdbcType="JAVA_OBJECT" property="progestation"
typeHandler="com.baomidou.mybatisplus.extension.handlers.JacksonTypeHandler"
javaType="com.esmooc.life.marriage.entity.Ppaal$PremaritalAndPremaritalInfo"/>

The content of this article is about the problems encountered in the work, and it is also the process of constantly fighting and upgrading. I hope you will communicate more and put forward valuable suggestions.

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