Question

I’m trying to create a simple web-site, which hosts topics and comments. I’ve begun with topics, and created repository for them:

package com.myProject.mvc3.repository;
import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;

@Repository
public interface TopicRepository extends CrudRepository<Topic, Integer>{    
     public List<Topic> findAllByTopicTag(Tag currentTag);
} 

And I’ve defined the path for my repository in the servlet-context.xml:

jpa:repositories base-package="com.myProject.mvc3.repository"

Now, I’d like to include the comments in my repository, and the following code doesn’t work:

package com.myProject.mvc3.repository;
import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;

@Repository
public interface CommentRepository extends CrudRepository<Comment, Integer> {
    public List<Comment> findTopicComments(Topic topic);

}

My project doesn’t build even. Can you give me an advice, how to create repositories for more than one entities (Topic class and Comment class are declared with @Entity)?

What i’m faciong:

• there is HDD pic on the TopicRepository class icon
• there is a question mark on the CommentRepository class icon
• error log (a huge one):

org.springframework.beans.factory.BeanCreationException: Error creating bean with name ‘org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping#0’: Initialization of bean failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name ‘topicController’: Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.epam.mvc3.service.CommentService com.epam.mvc3.controller.TopicController.commentService; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name ‘commentService’: Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.epam.mvc3.repository.CommentRepository com.epam.mvc3.service.CommentService.commentRepository; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name ‘commentRepository’: FactoryBean threw exception on object creation; nested exception is java.lang.IllegalArgumentException: No property find found for type class com.epam.mvc3.model.Comment
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:527)
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:293)
org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:290)
org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:192)
org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:585)
org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:895)
org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:425)
org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:467)
org.springframework.web.servlet.FrameworkServlet.createWebApplicationContext(FrameworkServlet.java:483)
org.springframework.web.servlet.FrameworkServlet.initWebApplicationContext(FrameworkServlet.java:358)
org.springframework.web.servlet.FrameworkServlet.initServletBean(FrameworkServlet.java:325)
org.springframework.web.servlet.HttpServletBean.init(HttpServletBean.java:127)
javax.servlet.GenericServlet.init(GenericServlet.java:160)
org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:928)
com.springsource.insight.collection.tcserver.request.HttpRequestOperationCollectionValve.invoke(HttpRequestOperationCollectionValve.java:84)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:987)
org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:539)
org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:298)
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
java.lang.Thread.run(Thread.java:722)

Answer 1

Just add By in findTopicComments so that it became findByTopicComments. Of course, this will work only if Comment entity has topicComments field or it has topic field which, in turn, has comments field.

Btw, you don’t need @Repository annotation on Spring-data-jpa repositories.

Actually, if your query name doesn’t match pattern ^(find|read|get)(\\p{Upper}.*?)??By from this class then the following occurs:

• any of the prefixes such as get, ‘read’ and find won’t be stripped and will be considered as the part of a JPQL query to generate. In this case you will get an exception:
  java.lang.IllegalArgumentException: No property find found for type class ....
• if there’s nothing to strip from your method name then it will be processed as if it had findBy prefix before.

Since this is not clear from docs I’ve created the issue in Spring Data Commons issue tracker.