Support controlling to use lazy Initialization or not on mapper scanning feature

[kazuki43zoo]

Since Spring Boot 2.2(not release yet), the lazy Initialization feature will be support. For details see https://spring.io/blog/2019/03/14/lazy-initialization-in-spring-boot-2-2. When it is enabled and one-to-one or one-to-many relationship map using @One or @Many, there are cases that it does not work fine.

Known case is as follow:

@Mapper
public interface GoodsMapper {
  @Select("select * from goods where id=#{goodsId}")
  @Results({
      @Result(id = true, column = "id", property = "id"),
      @Result(column = "name", property = "name"),
      @Result(column = "vendor_id", property = "vendor",
          one = @One(select = "com.example.mybatisspringboot22demo.VendorMapper.getVendor"))
  })
  Goods getGoods(@Param("goodsId") Integer goodsId);
}

@Mapper
public interface VendorMapper {

  @Select("select * from vendor where id=#{vendorId}")
  Vendor getVendor(@Param("vendorId") String vendorId);

}

org.mybatis.spring.MyBatisSystemException: nested exception is org.apache.ibatis.exceptions.PersistenceException: 
### Error querying database.  Cause: java.lang.IllegalArgumentException: Mapped Statements collection does not contain value for com.example.mybatisspringboot22demo.VendorMapper.getVendor
### The error may exist in com/example/mybatisspringboot22demo/GoodsMapper.java (best guess)
### The error may involve com.example.mybatisspringboot22demo.GoodsMapper.getGoods
### The error occurred while handling results
### SQL: select * from goods where id=?
### Cause: java.lang.IllegalArgumentException: Mapped Statements collection does not contain value for com.example.mybatisspringboot22demo.VendorMapper.getVendor

	at org.mybatis.spring.MyBatisExceptionTranslator.translateExceptionIfPossible(MyBatisExceptionTranslator.java:77)
	at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:446)
	at com.sun.proxy.$Proxy56.selectOne(Unknown Source)
	at org.mybatis.spring.SqlSessionTemplate.selectOne(SqlSessionTemplate.java:166)
	at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:87)
	at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:58)
	at com.sun.proxy.$Proxy58.getGoods(Unknown Source)
	at com.example.mybatisspringboot22demo.MybatisSpringBoot22DemoApplicationTests.contextLoads(MybatisSpringBoot22DemoApplicationTests.java:18)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.springframework.test.context.junit4.statements.RunBeforeTestExecutionCallbacks.evaluate(RunBeforeTestExecutionCallbacks.java:74)
	at org.springframework.test.context.junit4.statements.RunAfterTestExecutionCallbacks.evaluate(RunAfterTestExecutionCallbacks.java:84)
	at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75)
	at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86)
	at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84)
	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:251)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:97)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
	at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
	at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:190)
	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
	at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
	at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
	at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)
Caused by: org.apache.ibatis.exceptions.PersistenceException: 
### Error querying database.  Cause: java.lang.IllegalArgumentException: Mapped Statements collection does not contain value for com.example.mybatisspringboot22demo.VendorMapper.getVendor
### The error may exist in com/example/mybatisspringboot22demo/GoodsMapper.java (best guess)
### The error may involve com.example.mybatisspringboot22demo.GoodsMapper.getGoods
### The error occurred while handling results
### SQL: select * from goods where id=?
### Cause: java.lang.IllegalArgumentException: Mapped Statements collection does not contain value for com.example.mybatisspringboot22demo.VendorMapper.getVendor
	at org.apache.ibatis.exceptions.ExceptionFactory.wrapException(ExceptionFactory.java:30)
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:149)
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:140)
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectOne(DefaultSqlSession.java:76)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:433)
	... 36 more
Caused by: java.lang.IllegalArgumentException: Mapped Statements collection does not contain value for com.example.mybatisspringboot22demo.VendorMapper.getVendor
	at org.apache.ibatis.session.Configuration$StrictMap.get(Configuration.java:946)
	at org.apache.ibatis.session.Configuration.getMappedStatement(Configuration.java:739)
	at org.apache.ibatis.session.Configuration.getMappedStatement(Configuration.java:732)
	at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.getNestedQueryMappingValue(DefaultResultSetHandler.java:743)
	at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.getPropertyMappingValue(DefaultResultSetHandler.java:465)
	at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.applyPropertyMappings(DefaultResultSetHandler.java:441)
	at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.getRowValue(DefaultResultSetHandler.java:404)
	at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleRowValuesForSimpleResultMap(DefaultResultSetHandler.java:354)
	at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleRowValues(DefaultResultSetHandler.java:328)
	at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleResultSet(DefaultResultSetHandler.java:301)
	at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleResultSets(DefaultResultSetHandler.java:194)
	at org.apache.ibatis.executor.statement.PreparedStatementHandler.query(PreparedStatementHandler.java:65)
	at org.apache.ibatis.executor.statement.RoutingStatementHandler.query(RoutingStatementHandler.java:79)
	at org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:63)
	at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:324)
	at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:156)
	at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:109)
	at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:83)
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:147)
	... 43 more

Solutions

Add lazyInitialization option on <mybatis:scan> and @MapperScan. The default value is false(=not use lazy initialization). If developer want to use lazy initialization for mapper bean, it should be set to the true expressly.

e.g.)

<mybatis:scan base-package="org.mybatis.spring.mapper"
        lazy-initialization="${mybatis.lazy-initialization:false}" />

@MapperScan(basePackages = "org.mybatis.spring.mapper",
        lazyInitialization = "${mybatis.lazy-initialization:false}")
public class MyBatisConfig {
  // ...
}

Limitations

Description

If following feature use, cannot use lazy Initialization.

• ref statement on @One or @Many (<association select="..."> or <collection select="...">) with other mapper statement

• include fragment with other mapper statement (<include refid="...">)

• ref cache with other mapper cache (<cache-ref namespace="...">)

• ref resultMap with other mapper result map (<select resultMap="...">)

Solution for limitations

• Specify the bean name of dependency's mapper using @DependsOn (Spring's annotation)

@Mapper
@DependsOn("vendorMapper")
public interface GoodsMapper {
  // ...
}