Instantiation of bean failed : Specified class is an interface - spring

Question

I am facing an issue while creating a bean for dependency injection. Here is the scenario.
I am dealing with MongoDB repository, I have also created a class which uses it. I am trying to instantiate bean instance of both.
MongoDB reporsitory:
#Repository
public interface ProductGlobalTrendRepository extends MongoRepository<ProductGlobalTrend,String>{
public ProductGlobalTrend findByPid(#Param("pId") String pId);
}
The class which is using it:
#Service
#Scope("singleton")
public class ProductTrendService {
#Autowired
#Qualifier("productGlobalTrendRepo")
ProductGlobalTrendRepository productGlobalTrendRepo;
public ProductTrendService() {
super();
}
public void setProductGlobalTrendRepo(
ProductGlobalTrendRepository productGlobalTrendRepo) {
this.productGlobalTrendRepo = productGlobalTrendRepo;
}
public ProductTrendService(ProductGlobalTrendRepository productGlobalTrendRepo) {
super();
this.productGlobalTrendRepo = productGlobalTrendRepo;
}
}
The spring's bean config xml has these entries:
<bean id="productTrendService" class="com.api.services.ProductTrendService"> </bean>
<bean id="productGlobalTrendRepo" class="com.mongodb.repository.ProductGlobalTrendRepository"> </bean>
Following is the error I am getting:
19428 [localhost-startStop-1] WARN
org.springframework.web.context.support.AnnotationConfigWebApplicationContext
- Exception encountered during context initialization - cancelling refresh attempt
org.springframework.beans.factory.BeanCreationException: Error
creating bean with name 'productTrendService': Injection of autowired
dependencies failed; nested exception is
org.springframework.beans.factory.BeanCreationException: Could not
autowire field: com.mongodb.repository.ProductGlobalTrendRepository
com.api.services.ProductTrendService.productGlobalTrendRepo; nested
exception is org.springframework.beans.factory.BeanCreationException:
Error creating bean with name 'productGlobalTrendRepo' defined in
class path resource [com/vstore/conf/spring-security.xml]:
Instantiation of bean failed; nested exception is
org.springframework.beans.BeanInstantiationException: Failed to
instantiate [com.mongodb.repository.ProductGlobalTrendRepository]:
Specified class is an interface
It complains that repository is a interface class.
Can somebody please suggest a fix/workaround for this bean dependency injection ?

Answer 1

The problem is with the following information in your context file
<bean id="productGlobalTrendRepo"
class="com.mongodb.repository.ProductGlobalTrendRepository">
</bean>
You should create a class com.mongodb.repository.ProductGlobalTrendRepositoryImpl which implements com.mongodb.repository.ProductGlobalTrendRepository and provides implementation of its methods.
then change your bean declaration info as
<bean id="productGlobalTrendRepo"
class="com.mongodb.repository.ProductGlobalTrendRepositoryImpl">
</bean>
Behind the scene the object is created which is not possible with the interface.