get auto-genearated key for the inserted record in mybatis - spring-mvc

Question

I am working under a web application which use spring mvc + mybatis + mysql.
And I found that I can not get the auto-generated key for the last inserted record (I have googled so much).
This is the related configuration(take the model 'Post' for example):
spring.xml:
<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
//omitted
</bean>
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<property name="dataSource" ref="dataSource" />
<property name="configLocation" value="config.xml" />
</bean>
<bean id="sqlSession" class="org.mybatis.spring.SqlSessionTemplate">
<constructor-arg index="0" ref="sqlSessionFactory" />
</bean>
mybatis config.xml
<configuration>
<typeAliases>
<typeAlias alias="Post" type="com.king.model.Post" />
</typeAliases>
<mappers>
<mapper resource="com/king/model/PostMapper.xml" />
</mappers>
</configuration>
PostMapper.xml:
<mapper namespace="com.king.model.PostMapper">
<insert id="insert" parameterType="Post">
insert into posts (title,body,created_at,updated_at) values (#{title},#{body},#{createDate},#{updateDate})
</insert>
</mapper>
Dao:
public abstract class AbstractSimpleDaoImpl<T> extends SqlSessionDaoSupport{
#Override
public int add(T entity) {
return getSqlSession().insert(getMapperNamespace() + ".insert", entity);
}
protected abstract String getMapperNamespace();
}
public class PostDao extends AbstractSimpleDaoImpl<Post> {
#Override
protected String getMapperNamespace() {
return "com.king.model.PostMapper";
}
}
However,when I insert a new Post to database:
postDao.add(post);
I can not get the generated id for the inserted post. I always get 1. I know this is the row-affected number.
Also,I read the mybatis guide,and I tried this:
<insert id="insert" parameterType="Post" useGeneratedKeys="true" keyProperty="id">
But it seems that,this does not work.
How to fix it?

Answer 1

In fact the following works:
<insert id="insert" parameterType="Post" useGeneratedKeys="true" keyProperty="id">
postDao.add(post);
will return 1 as before,but post.getId() will get the key.

Answer 2

This can be done using annotations as well.
final String INSERT = "insert into posts (title,body,created_at,updated_at) values (#{title},#{body},#{createDate},#{updateDate})";
#Insert(INSERT)
#Options(useGeneratedKeys = true, keyProperty = "id", keyColumn = "id")
void insert(Post post) throws Exception;
Set keyProperty as the Java variable name.
Set keyColumn as the column name in the database.
After insert, post.getId() will have your generated ID.

Answer 3

Try using the following code; I added the keyColumn field to your code:
<insert id="insert" parameterType="Post" useGeneratedKeys="true" keyProperty="id" keyColumn="id">
Alternatively, if you are using PostgreSql:
<insert id="insert" parameterType="Post" useGeneratedKeys="true" keyProperty="id" keyColumn="id">
<selectKey keyProperty="id" resultType="java.lang.Integer">
SELECT
currVal('your_tbl_seq') as id
</selectKey> </insert>

Answer 4

This will work for Spring Boot using annotations and getting the id as a return value as in your original question.
#Insert("insert into sources (host, created_at) values (#{host}, now())")
#SelectKey(statement="select LAST_INSERT_ID()", keyProperty="id", before=false, resultType=long.class)
long create(#Param("host") String host);
Then long id = sourceMapper.create("abc"); would return your primary key.