Use code in error query parameter. Closes #5

End users should have the possibility to provide their own
error messages. Therefore not the message, instead the error
code is provided.

src/main/java/de/nclazz/service/mailrelay/MailRelayApplication.java

@@ -5,7 +5,10 @@ import org.springframework.beans.factory.annotation.Value;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
 import org.springframework.boot.web.servlet.FilterRegistrationBean;
+import org.springframework.context.MessageSource;
 import org.springframework.context.annotation.Bean;
+import org.springframework.context.support.ReloadableResourceBundleMessageSource;
+import org.springframework.validation.beanvalidation.LocalValidatorFactoryBean;
 
 import java.time.Clock;
 
@@ -31,4 +34,20 @@ public class MailRelayApplication {
         return registrationBean;
     }
 
+    @Bean
+    public MessageSource messageSource() {
+        ReloadableResourceBundleMessageSource messageSource = new ReloadableResourceBundleMessageSource();
+
+        messageSource.setBasename("classpath:messages/messages");
+        messageSource.setDefaultEncoding("UTF-8");
+        return messageSource;
+    }
+
+    @Bean
+    public LocalValidatorFactoryBean getValidator() {
+        LocalValidatorFactoryBean bean = new LocalValidatorFactoryBean();
+        bean.setValidationMessageSource(messageSource());
+        return bean;
+    }
+
 }

src/main/java/de/nclazz/service/mailrelay/adapter/web/MessageForm.java

@@ -16,17 +16,17 @@ import java.time.LocalDateTime;
 @NoArgsConstructor
 public class MessageForm {
 
-    @NotBlank
+    @NotBlank(message = "{field.notblank}")
     private String token;
 
-    @NotBlank
+    @NotBlank(message = "{field.notblank}")
     private String subject;
 
-    @NotBlank
+    @NotBlank(message = "{field.notblank}")
     private String content;
 
-    @Pattern(regexp = StringUtils.EMAIL_RFC_5322_REGEX)
-    @NotBlank
+    @Pattern(regexp = StringUtils.EMAIL_RFC_5322_REGEX, message = "{field.pattern.email}")
+    @NotBlank(message = "{field.notblank.email}")
     private String from;
 
 

src/main/java/de/nclazz/service/mailrelay/adapter/web/MessageFormController.java

@@ -54,14 +54,15 @@ public class MessageFormController {
         String queryParams = bindingResult.getAllErrors().stream()
                 .map(ValidationError::fromObjectError)
                 .map(MessageFormController::mapValidationErrorToQueryParam)
+                .distinct()
                 .collect(Collectors.joining("&"));
         String origin = form.getOnError() != null ? form.getOnError() : referer;
 
-        return origin + "?" + URLEncoder.encode(queryParams, StandardCharsets.UTF_8);
+        return origin + "?" + queryParams;
     }
 
     private static String mapValidationErrorToQueryParam(ValidationError error) {
-        return String.format("%s=%s", error.getTarget(), error.getMessage());
+        return String.format("%s=%s", error.getTarget(), URLEncoder.encode(error.getCode(), StandardCharsets.UTF_8));
     }
 
 

src/main/java/de/nclazz/service/mailrelay/adapter/web/ValidationError.java

@@ -14,12 +14,15 @@ public class ValidationError {
     private String target;
     private String message;
     private Object rejected;
+    private String code;
 
     public static ValidationError fromObjectError(ObjectError error) {
+        FieldError fieldError = (FieldError) error;
         return new ValidationError(
-                ((FieldError)error).getField(),
+                fieldError.getField(),
                 error.getDefaultMessage(),
-                ((FieldError) error).getRejectedValue()
+                fieldError.getRejectedValue(),
+                fieldError.getCode()
         );
     }
 

src/main/resources/messages/messages.properties

@@ -0,0 +1,4 @@
+field.notblank=This field is mandatory
+field.notblank.email=Please provide a valid email
+field.pattern=Invalid format
+field.pattern.email=Please provide a valid email

src/main/resources/messages/messages_DE.properties

@@ -0,0 +1,4 @@
+field.notblank=Dies ist ein Pflichtfeld
+field.notblank.email=Bitte geben Sie eine gültige Email ein
+field.pattern=Ungültiges Format
+field.pattern.email=Bitte geben Sie eine gültige Email ein