unable to create Rich Email using Thymeleaf and Spring

Question

I have been trying to create and send Rich HTML emails using Thymeleaf. After number of hiccups I came across what i hope is my last issue.

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.thymeleaf.exceptions.TemplateProcessingException: Resource resolution by ServletContext with org.thymeleaf.resourceresolver.ServletContextResourceResolver can only be performed when context implements org.thymeleaf.context.IWebContext [current context: org.thymeleaf.context.Context]
    org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:973)
    org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:852)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:620)
    org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:837)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
    org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:118)
    org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:84)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:103)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:113)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:150)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:45)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:184)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:105)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:87)
    org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:192)
    org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160)
    org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:344)
    org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:261)

I have the following WebConfig.java setup:

@Bean
public ServletContextTemplateResolver templateResolver() {
    ServletContextTemplateResolver resolver = new ServletContextTemplateResolver();
    resolver.setPrefix("/WEB-INF/pages/");
    resolver.setSuffix(".html");
    resolver.setTemplateMode("HTML5");
    resolver.setCacheable(false);
    resolver.setOrder(2);
    return resolver;

}

@Bean
public ClassLoaderTemplateResolver emailTemplateResolver() {
    ClassLoaderTemplateResolver resolver = new ClassLoaderTemplateResolver();
    resolver.setPrefix("mail/");
    resolver.setTemplateMode("HTML5");
    resolver.setCharacterEncoding("UTF-8");
    resolver.setOrder(1);
    return resolver;
}

@Bean
public SpringTemplateEngine templateEngine() {
    SpringTemplateEngine engine = new SpringTemplateEngine();
    Set<ITemplateResolver> resolvers = new HashSet<>();

    resolvers.add(templateResolver());
    resolvers.add(emailTemplateResolver());

    engine.setTemplateResolvers(resolvers);
    return engine;
}

@Bean
public ViewResolver viewResolver() {
    ThymeleafViewResolver viewResolver = new ThymeleafViewResolver();
    viewResolver.setTemplateEngine(templateEngine());
    viewResolver.setOrder(1);
    viewResolver.setViewNames(new String[]{"*"});
    viewResolver.setCache(false);
    return viewResolver;
}

which is called at root config via getRootConfigClasses() from AbstractAnnotationConfigDispatcherServletInitializer.

Finally my class CustomSendMailImplementation.java contains the sendMail function which creates and sends email.

@Override
    public void sendMail(final String mailFrom, final String mailTo, final String subject, final String mailBody, final Locale locale) {

        final Context ctx = new Context(locale);
        ctx.setVariable("name", "JamesBond");
        ctx.setVariable("subscriptionDate", new Date());
        ctx.setVariable("hobbies", Arrays.asList("Cinema", "Sports", "Music"));


        final String htmlContent = this.templateEngine.process("testmail.html", ctx);

        try {
            mailSender.send(new MimeMessagePreparator() {
                public void prepare(MimeMessage mimeMessage)
                        throws Exception {
                    MimeMessageHelper message = new MimeMessageHelper(mimeMessage,
                            true, "UTF-8");
                    message.setFrom(mailFrom);
                    message.addTo(mailTo);
                    message.setSubject(subject);
                    message.setText(htmlContent, true);
                }
            });
        } catch (MailSendException e) {}
    }

What am i missing that is causing this issue to appear?

Answer 1

You cannot use the servletTemplateResolver as you have no servletcontext available (normally) during the creation of an email.

I'm not sure if you use a second templateEngine for mail generation yet, but you should definately create one for this purpose and one for webpage rendering.

Also take care in your bean configuration. If you fetch the templateResolver with the method as you did you are not using the Spring-managed version! So you are basically creating two objects. One spring managed and another one when calling the "factory" yourself. Rather use method parameters to autowire the needed parameters or probably even better just create managed beans if you need them managed by spring, which in the resolvers case is not necessary. (Most likely)

Answer 2

I got that example it working. Did you put the /mail folder in the src/java/resources directory? It belongs there, and not in WEB-INF because the ClassLoaderTemplateResolver will not look in the WEB-INF directory, and if it doesn't find the template then it passes the buck to the ServletContextTemplateResolver which gives the error you are getting.