ThymeleafView: java.lang.IllegalArgumentException: Property 'locale' is required - spring-boot

Question

I follow the below tutorial step by step to complete NO.10 Rendering Template Fragments.
https://www.thymeleaf.org/doc/tutorials/3.0/thymeleafspring.html#rendering-template-fragments
And I get an exception: nested exception is java.lang.IllegalArgumentException: Property 'locale' is required.
My code is below, Could someone tell me how to fix it? Thank you very much.
WebConfig.java
public class WebConfig implements WebMvcConfigurer {
#Autowired
private WebApplicationContext context;
#Bean
public ServletContextTemplateResolver templateResolver() {
final ServletContextTemplateResolver resolver = new ServletContextTemplateResolver(context.getServletContext());
resolver.setPrefix("/WEB-INF/views/");
resolver.setSuffix(".html");
resolver.setTemplateMode(TemplateMode.HTML);
return resolver;
}
#Bean
public SpringTemplateEngine templateEngine() {
SpringTemplateEngine templateEngine = new SpringTemplateEngine();
templateEngine.setTemplateResolver(templateResolver());
return templateEngine;
}
#Bean
public ThymeleafViewResolver viewResolver() {
ThymeleafViewResolver viewResolver = new ThymeleafViewResolver();
viewResolver.setTemplateEngine(templateEngine());
return viewResolver;
}
#Bean("messageSource")
public MessageSource messageSource() {
ResourceBundleMessageSource messageSource = new ResourceBundleMessageSource();
messageSource.setBasenames("lang/messages");
messageSource.setDefaultEncoding("UTF-8");
return messageSource;
}
#Bean
public LocaleResolver localeResolver() {
return new CookieLocaleResolver();
}
#Override
public void addInterceptors(InterceptorRegistry registry) {
LocaleChangeInterceptor localeChangeInterceptor = new LocaleChangeInterceptor();
localeChangeInterceptor.setParamName("lang");
registry.addInterceptor(localeChangeInterceptor);
}
#Bean(name = "content-part")
#Scope("prototype")
public ThymeleafView someViewBean() {
ThymeleafView view = new ThymeleafView("index"); // templateName = 'index'
view.setMarkupSelector("content");
return view;
}
}
HomeController.java
public class HomeController {
#RequestMapping("/showContentPart")
public String showContentPart(final Locale locale, HttpServletRequest request, HttpServletResponse response) {
return "content-part";
}
}
index.html
https://i.stack.imgur.com/WOGpR.png

Answer 1

Try this :
#RequestMapping("/showContentPart")
public class HomeController
{
public String showContentPart(final Locale locale, HttpServletRequest request, HttpServletResponse response) {
return "content-part";
}