Document how to opt back in to DataSource auto-configuration when using R2DBC

[busches]

After upgrading out application from Spring Boot 2.2.8 to 2.3.0 (2.3.1 also fails) we are now getting the following error when running our tests:

Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {}
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoMatchingBeanFound(DefaultListableBeanFactory.java:1714)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1270)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1224)
	at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:884)
	at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:788)
	... 108 more

Here's a simplistic reproduction example of it failing on 2.3.1 once I add in the r2dbc dependency: https://github.com/busches/spring-boot-issue

[wilkinsona]

NamedParameterJdbcTemplate is for use with JDBC rather than R2DBC. You may not have spring-jdbc on the classpath which would stop it from being auto-configured.

If you would like us to spend some more time investigating, please spend some time providing a complete yet minimal sample that reproduces the problem. You can share it with us pushing it to a separate repository on GitHub or by zipping it up and attaching it to this issue.

[busches]

NamedParameterJdbcTemplate is for use with JDBC rather than R2DBC. You may not have spring-jdbc on the classpath which would stop it from being auto-configured.

If you would like us to spend some more time investigating, please spend some time providing a complete yet minimal sample that reproduces the problem. You can share it with us pushing it to a separate repository on GitHub or by zipping it up and attaching it to this issue.

I can work on that, but it seems odd that if I change only to spring boot 2.3 it fails to find the bean. We use both R2DBC and JDBC, I only pointed out R2DBC as maybe it was causing a conflict.

[wilkinsona]

There’s no R2DBC support in Spring Boot 2.2 so switching to 2.3 is more than just a version change. IIRC, the experimental R2DB2 support depended on spring-jdbc whereas the support that was added in Spring Boot 2.3 does not. You could check your dependencies and/or run with --debug to verify this for yourself.

[busches]

There’s no R2DBC support in Spring Boot 2.2 so switching to 2.3 is more than just a version change. IIRC, the experimental R2DB2 support depended on spring-jdbc whereas the support that was added in Spring Boot 2.3 does not. You could check your dependencies and/or run with --debug to verify this for yourself.

Yea, that's not the issue at all, I believe it has to do with @TestComponent and bringing in the dependency. Here's a repro case: https://github.com/busches/spring-boot-issue

I have this test that passes with bringing it in via @Autowired: https://github.com/busches/spring-boot-issue/blob/master/src/test/kotlin/com/example/demo/PassingApplicationTests.kt
And this test fails when it's brought in via a @TestComponent: https://github.com/busches/spring-boot-issue/blob/master/src/test/kotlin/com/example/demo/FailingApplicationTests.kt
Downgrading to 2.2.8 and both pass.

[wilkinsona]

Thanks for the sample, but it seems to fail with both 2.3.1 and 2.2.8. That's what I would expect as FailingApplicationTests is using classes = [MyComponent::class]. With class configuration, @SpringBootTest does not search for the main application class. As a result, DemoApplication and its @SpringBootApplication annotation aren't found so auto-configuration isn't enabled.

If you can provide a sample that passes with 2.2.x and fails with 2.3.x we can take another look. At the moment it looks to be user error as auto-configuration isn't enabled in FailingApplicationTests but you're trying to consume an auto-configured bean.

[busches]

Thanks for the sample, but it seems to fail with both 2.3.1 and 2.2.8. That's what I would expect as FailingApplicationTests is using classes = [MyComponent::class]. With class configuration, @SpringBootTest does not search for the main application class. As a result, DemoApplication and its @SpringBootApplication annotation aren't found so auto-configuration isn't enabled.

If you can provide a sample that passes with 2.2.x and fails with 2.3.x we can take another look. At the moment it looks to be user error as auto-configuration isn't enabled in FailingApplicationTests but you're trying to consume an auto-configured bean.

Hmm, swore I had it failing in 2.2.8 as well, I must have made a mistake. I'll see if I can get it to fail with this simplistic example or if I need to make it more complicated to resemble our real example.