feat: validate rest input using bean validation and add a mapper for …

…constraint violations

AMW_rest/src/main/java/ch/mobi/itc/mobiliar/rest/RESTApplication.java

@@ -88,6 +88,7 @@ private void addRestResourceClasses(Set<Class<?>> resources) {
         resources.add(ValidationExceptionMapper.class);
         resources.add(NotFoundExceptionMapper.class);
         resources.add(UncaughtExceptionMapper.class);
+        resources.add(ConstraintViolationExceptionMapper.class);
 
         // health
         resources.add(HealthCheck.class);

AMW_rest/src/main/java/ch/mobi/itc/mobiliar/rest/exceptions/ConstraintViolationExceptionMapper.java

@@ -0,0 +1,20 @@
+package ch.mobi.itc.mobiliar.rest.exceptions;
+
+import javax.validation.ConstraintViolation;
+import javax.validation.ConstraintViolationException;
+import javax.ws.rs.core.Response;
+import javax.ws.rs.ext.ExceptionMapper;
+import java.util.stream.Collectors;
+
+public class ConstraintViolationExceptionMapper implements ExceptionMapper<ConstraintViolationException> {
+
+    @Override
+    public Response toResponse(ConstraintViolationException e) {
+        final String message = e.getConstraintViolations().stream()
+                .map(ConstraintViolation::getMessage)
+                .distinct() // since we use CDI and JAX-RS, there is potential that the validation kicks in twice.
+                            // calling distinct on the list of messages makes sure, that each message is included only once.
+                .collect(Collectors.joining("\n"));
+                return Response.status(Response.Status.BAD_REQUEST).entity(new ExceptionDto(message)).build();
+    }
+}

AMW_rest/src/main/java/ch/mobi/itc/mobiliar/rest/tags/boundary/TagsRest.java

@@ -1,7 +1,6 @@
 package ch.mobi.itc.mobiliar.rest.tags.boundary;
 
 import ch.mobi.itc.mobiliar.rest.dtos.TagDTO;
-import ch.mobi.itc.mobiliar.rest.exceptions.ExceptionDto;
 import ch.puzzle.itc.mobiliar.business.property.boundary.AddTagUseCase;
 import ch.puzzle.itc.mobiliar.business.property.boundary.ListTagsUseCase;
 import ch.puzzle.itc.mobiliar.business.property.boundary.RemoveTagUseCase;
@@ -10,15 +9,13 @@
 import ch.puzzle.itc.mobiliar.common.exception.ValidationException;
 import io.swagger.annotations.Api;
 import io.swagger.annotations.ApiOperation;
-import lombok.NonNull;
 
 import javax.ejb.Stateless;
 import javax.inject.Inject;
 import javax.validation.constraints.NotNull;
 import javax.ws.rs.*;
 import javax.ws.rs.core.Response;
 import java.net.URI;
-import java.util.Objects;
 
 import static javax.ws.rs.core.MediaType.APPLICATION_JSON;
 import static javax.ws.rs.core.Response.Status.CREATED;
@@ -44,16 +41,14 @@ public class TagsRest {
 
     @ApiOperation(value = "Gets all tags")
     public Response getAllTags() {
-        return Response
-                .status(OK)
-                .entity(listTagsUseCase.get())
-                .build();
+        return Response.status(OK).entity(listTagsUseCase.get()).build();
     }
 
     @POST
     @ApiOperation(value = "Adds one tag")
-    public Response addOneTag(TagDTO tagDTO) throws ValidationException {
-        if(Objects.isNull(tagDTO)) throw new ValidationException("Tag must not be null.");
+    public Response addOneTag(
+            @NotNull(message = "Tag must not be null.") TagDTO tagDTO) throws ValidationException {
+
         TagCommand tagCommand = new TagCommand(tagDTO.getName());
         PropertyTagEntity newTag = addTagUseCase.addTag(tagCommand);
         return Response