thymeleaf error - thymeleaf

Question

Below code throw error of unresolvable circular reference. when Spring is trying to create bean of MessageFormatHelper class.This error throw while I run the jar. I try to see but not getting what is reason. Could anyone help.
First class,
#Component
class DbTemplateResolver extends TemplateResolver {
#Autowired
SpringTemplateEngine templateEngine;
....othercode
#PostConstruct
public void extension() {
templateEngine.addTemplateResolver(this);
}
...other code
}
Second class,
#Component
class MessageFormatHelper{
#Autowired
SpringTemplateEngine templateEngine;
... other code
String getMessage()
{
final Context ctx = new Context(locale);
ctx.setVariable("contractMap", model.get(ContractMap.TEMPLATE_MODEL_MAP_KEY));
mergedMessage = templateEngine.process(fileName, ctx);
}
}
Full error:
Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.flex.eventManagement.handler.helper.MessageFormatHelper com.flex.eventManagement.handler.helper.NotificationPreProcessor.messageFormatHelper; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'messageFormatHelper': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: org.thymeleaf.spring4.SpringTemplateEngine com.flex.eventManagement.handler.helper.MessageFormatHelper.templateEngine; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration$ThymeleafDefaultConfiguration': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private final java.util.Collection org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration$ThymeleafDefaultConfiguration.templateResolvers; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dbTemplateResolver': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: org.thymeleaf.spring4.SpringTemplateEngine com.flex.eventManagement.handler.helper.DbTemplateResolver.templateEngine; nested exception is org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'templateEngine': Requested bean is currently in creation: Is there an unresolvable circular reference?
Updated
Remove template engine auto-wire from DbTemplateResolver class. Autowire into MessageFormatHelper.java class like below
class MessageFormatHelper{
#Bean
public DbTemplateResolver dbTemplateResolver() {
DbTemplateResolver resolver = new DbTemplateResolver();
resolver.setOrder(2);
return resolver;
}
#Bean
public SpringTemplateEngine thymeleafTemplateEngine() {
SpringTemplateEngine engine = new SpringTemplateEngine();
engine.setTemplateResolvers(Sets.newHashSet(dbTemplateResolver()));
return engine;
}
}
Also I need to remove SpringTemplateEngine auto wired from MessageFormatHelper right? so how can I call mergedMessage = templateEngine.process(fileName, ctx);?
Update 2.
should followed required in MessageFormatHelper
#Autowired
DbTemplateResolver dbTemplateResolver;
#Autowired
SpringTemplateEngine templateEngine;
#PostConstruct
public void extension() {
templateEngine.addTemplateResolver(dbTemplateResolver);
}

Answer 1

Your code is flawed and it seems you lack basic understanding of how Spring works and how you should use Spring to configure things.
First you are using Spring Boot and want to use Thymeleaf. This is simply done by added the spring-boot-starter-thymeleaf as a dependency for you project. (I assume you have already done this).
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-thymeleaf<artifactId>
</dependency>
Spring Boot detects the fact that you have Thymeleaf on your classpath and the ThymeleafAutoConfiguration will kick in and configure the SpringTemplateEngine for you. It will even detect every bean of the type ITemplateResolver, which I assume your DbTemplateResolver implements.
The only thing to have your DbTemplateResolver add is to add a #Bean method to an #Configuration (or your application) class.
#Bean
public ITemplateResolver dbTemplateResolver() {
return new DbTemplateResolver();
}
Spring will detect it and inject it into the automatically configured SpringTemplateEngine.
The only thing you need to do is in classes you need the SpringTemplateEngine you need to auto wire it. Just use the super class not the concrete type.
#Autowired
private TemplateEngine templateEngine;
Don't mess around with trying to configure it later on, use the framework for that.