Spring RESTful API :: Using Traits for the #RestController methods - spring

Question

I'm trying to set up spring to use scala traits for the REST controllers.
Let's say I need 2 resources exposed: Author and Publication.
Here's the author:
AuthorController.java
#RestController
class AuthorController extends BaseController
with ReadTrait
{
def getSuffix(): String = {
"author"
}
}
and here's the publication:
PublicationController.java
#RestController
class PublicationController extends BaseController
with ReadTrait
{
def getSuffix(): String = {
"publication"
}
}
they both use the read trait.
and the read trait I need for both:
ReadTrait.java
#RestController
trait ReadTrait {
def getSuffix(): String
#Secured(Array("ROLE_USER"))
#RequestMapping(value = Array("/{resource}"), method = Array(RequestMethod.GET))
def read(#PathVariable("resource") resource: String): Author = {
if (resource == "author") {
// ...
}
}
}
So the problem that I'm facing is that Spring blows up when those 2 classes use the same trait with this:
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'requestMappingHandlerMapping' defined in class path resource [org/springframework/boot/autoconfigure/web/WebMvcAutoConfiguration$EnableWebMvcConfiguration.class]: Invocation of init method failed; nested exception is java.lang.IllegalStateException: Ambiguous mapping found. Cannot map 'publicationController' bean method
public abstract com.example.project.core.Author com.example.project.api._trait.ReadTrait.read(java.lang.String)
to {[/{resource}],methods=[GET],params=[],headers=[],consumes=[],produces=[],custom=[]}: There is already 'authorController' bean method
public abstract com.example.project.core.Author com.example.project.api._trait.ReadTrait.read(java.lang.String) mapped.
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1574)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:539)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:476)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:303)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:299)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:755)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:757)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:480)
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:118)
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:686)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:320)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:957)
at org.springframework.boot.SpringApplication.run(SpringApplication.java:946)
at com.example.project.Application.main(Application.java:10)
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:497)
at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:53)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.IllegalStateException: Ambiguous mapping found. Cannot map 'publicationController' bean method
public abstract com.example.project.core.Author com.example.project.api._trait.ReadTrait.read(java.lang.String)
to {[/{resource}],methods=[GET],params=[],headers=[],consumes=[],produces=[],custom=[]}: There is already 'authorController' bean method
public abstract com.example.project.core.Author com.example.project.api._trait.ReadTrait.read(java.lang.String) mapped.
at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.registerHandlerMethod(AbstractHandlerMethodMapping.java:212)
at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.detectHandlerMethods(AbstractHandlerMethodMapping.java:184)
at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.initHandlerMethods(AbstractHandlerMethodMapping.java:144)
at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.afterPropertiesSet(AbstractHandlerMethodMapping.java:123)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping.afterPropertiesSet(RequestMappingHandlerMapping.java:126)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1633)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1570)
... 21 common frames omitted
Everything builds fine and works as expected when I remove one of the Controllers. It also builds fine but doesn't work if I remove the #RestController annotation on the ReadTrait. Is the approach I'm trying out wrong? How can I make it work?
Thanks

Answer 1

You are confusing Spring Boot with multiple RestController without distinctive mapping.
You have to assign different RequestMapping values for each RestController class.