How automatically update fields like created/modified Date when using MyBatis? - spring

Question

I am using MyBatis and want to implement 2 fields on every table 'created', 'modified'. Both off them are date fields. Is there a way of automatically update these fields on an insert or update? Of course, I can adjust the mappings, but I was wondering if there is a more generic and DRY way of doing this?

Answer 1

No, mybatis has no mechanism to do this automatically without you coding your sql maps to update the columns.
One alternative would be database triggers. I'm not certain I would recommend that though, we just code it in the sql maps.
You could code it in the SQL maps like this,
<insert id="someInsert">
insert into dummy_table
(
SOME_COLUMN,
CREATED_DT
)
values
(
#{someValue},
sysdate
)
</insert>
or,
<update id="someUpdate">
update some_table
set some_column = #{someValue}, modified=sysdate
where some_id = #{someId}
</update>

Answer 2

you can use mybatis Interceptor
here is my example (using springboot):
in mycase, BaseEntity is the super class of all entity,i need do some thing before update or insert to database by mybatis.
step 1: create init method in BaseEntity for update or insert
public class BaseEntity{
private Date created;
private Date updated;
//getter,setter
public void initCreateEntity() {
this.created = new Date()
this.updated = new Date()
}
public void initUpdateEntity() {
this.created = new Date()
this.updated = new Date()
}
}
step 2: add a mybatis interceptor
import org.apache.ibatis.executor.Executor;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.mapping.SqlCommandType;
import org.apache.ibatis.plugin.*;
/**
* add time interceptor for update
*/
#Intercepts(#Signature(type = Executor.class, method = "update", args={MappedStatement.class, Object.class}))
public class BaseEntityInterceptor implements Interceptor {
#Override
public Object intercept(Invocation invocation) throws Throwable {
MappedStatement mappedStatement = (MappedStatement)invocation.getArgs()[0];
// get sql
SqlCommandType sqlCommandType = mappedStatement.getSqlCommandType();
// get parameter , this is the target object that you want to handle
Object parameter = invocation.getArgs()[1];
// make sure super class is BaseEntity
if (parameter instanceof BaseEntity) {
//init
BaseEntity baseEntity = (BaseEntity) parameter;
if (SqlCommandType.INSERT.equals(sqlCommandType)) {
baseEntity.initCreateEntity();
} else if (SqlCommandType.UPDATE.equals(sqlCommandType)) {
baseEntity.initUpdateEntity();
}
}
return invocation.proceed();
}
#Override
public Object plugin(Object o) {
return Plugin.wrap(o, this);
}
#Override
public void setProperties(Properties properties) {
}
}
step 3: add to bean Context in springboot config
#Configuration
public class MyBatisConfig {
#Bean
public BaseEntityInterceptor baseEntityInterceptor() {
return new BaseEntityInterceptor();
}
}
step 4: Dao and Mapper.xml
//base update or insert sql incloude column created and updated
eg:Dao
#Mapper
public interface BaseDao {
int update(BaseEntity baseEntity);
}
Mapper.xml
<update id="update" parameterType="com.package.to.BaseEntity">
update baseentity_table set created = #{createTime, jdbcType=TIMESTAMP}
updated = #{createTime, jdbcType=TIMESTAMP}
</update>
step 5: test
baseDao.update(new BaseEntity);
More information here: https://mybatis.org/mybatis-3/configuration.html#plugins