Empty Iterator returned on Cursor when it is already closed

[tacoo]

MyBatis version

mybatis-spring-boot-starter: 1.3.2
mybatis: 3.4.6

Database vendor and version

PostgreSQL: 9.6

Test case or example project

https://github.com/tacoo/mybatis-cursor

Steps to reproduce

Define a mapper method with return type org.apache.ibatis.cursor.Cursor
https://github.com/tacoo/mybatis-cursor/blob/master/src/main/java/example/AMapper.java#L14

Also I tested a method with return type org.apache.ibatis.session.ResultHandler. It works as expected.

Expected result

Return a cursor that has 1 record.

Actual result

Returned an empty cursor.

[kazuki43zoo]

@tacoo Thanks for your reporting.

You should be operated a Cursor with session is opened. In your application(= using mapper in spring application), you should be operated a Cursor at transactional method as follow:

@Repository
public class ARepository {

	private final AMapper aMapper;

+	@Transactional(readOnly = true)
	public void whyCursorWhy() {
		cursor();
		resultHandler();
	}

	// ...

}

[tacoo]

@kazuki43zoo

Thank you for your prompt reply.

It worked after adding Transactional annotation on the repository method. I understood that it requires to open a session before use a Cursor.

I think it would be great if mybatis throws an error when return type Cursor method called without opened session.

Thank you

[kazuki43zoo]

@tacoo Thanks for your feedback.
I've submitted a PR for this.