Spring Data Rest Validators introduction (#650)

* - created packages for each logical part of application
- created validator for WebsiteUser rest API
- created ValidatorEventRegister class which fixes known bug for not
detecting generated events
- created custom Exception Handler which creates better response
messages

* Code formatting

* formated pom.xml
replaced for loops with streams
fixed bug while getting all beans

* removed unnecessary code
changed repository type

* - added test for Spring Data REST APIs
- changed bad request return code
- formated code

spring-data-rest/pom.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
 
     <groupId>com.baeldung</groupId>
@@ -15,7 +15,7 @@
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-parent</artifactId>
         <version>1.3.3.RELEASE</version>
-        <relativePath/> <!-- lookup parent from repository -->
+        <relativePath /> <!-- lookup parent from repository -->
     </parent>
 
     <properties>

spring-data-rest/src/main/java/com/baeldung/SpringDataRestApplication.java

@@ -5,7 +5,7 @@ import org.springframework.boot.autoconfigure.SpringBootApplication;
 
 @SpringBootApplication
 public class SpringDataRestApplication {
-	public static void main(String[] args) {
-		SpringApplication.run(SpringDataRestApplication.class, args);
-	}
+    public static void main(String[] args) {
+        SpringApplication.run(SpringDataRestApplication.class, args);
+    }
 }

spring-data-rest/src/main/java/com/baeldung/UserRepository.java

@@ -1,12 +0,0 @@
-package com.baeldung;
-
-import org.springframework.data.repository.PagingAndSortingRepository;
-import org.springframework.data.repository.query.Param;
-import org.springframework.data.rest.core.annotation.RepositoryRestResource;
-
-import java.util.List;
-
-@RepositoryRestResource(collectionResourceRel = "users", path = "users")
-public interface UserRepository extends PagingAndSortingRepository<WebsiteUser, Long> {
-    List<WebsiteUser> findByName(@Param("name") String name);
-}

spring-data-rest/src/main/java/com/baeldung/config/ValidatorEventRegister.java

@@ -0,0 +1,30 @@
+package com.baeldung.config;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+
+import org.springframework.beans.factory.InitializingBean;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.data.rest.core.event.ValidatingRepositoryEventListener;
+import org.springframework.validation.Validator;
+
+@Configuration
+public class ValidatorEventRegister implements InitializingBean {
+
+    @Autowired
+    ValidatingRepositoryEventListener validatingRepositoryEventListener;
+
+    @Autowired
+    private Map<String, Validator> validators;
+
+    @Override
+    public void afterPropertiesSet() throws Exception {
+        List<String> events = Arrays.asList("beforeCreate", "afterCreate", "beforeSave", "afterSave", "beforeLinkSave", "afterLinkSave", "beforeDelete", "afterDelete");
+        
+        for (Map.Entry<String, Validator> entry : validators.entrySet()) {
+            events.stream().filter(p -> entry.getKey().startsWith(p)).findFirst().ifPresent(p -> validatingRepositoryEventListener.addValidator(p, entry.getValue()));
+        }
+    }
+}

spring-data-rest/src/main/java/com/baeldung/exception/handlers/RestResponseEntityExceptionHandler.java

@@ -0,0 +1,25 @@
+package com.baeldung.exception.handlers;
+
+import java.util.stream.Collectors;
+
+import org.springframework.data.rest.core.RepositoryConstraintViolationException;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.ControllerAdvice;
+import org.springframework.web.bind.annotation.ExceptionHandler;
+import org.springframework.web.context.request.WebRequest;
+import org.springframework.web.servlet.mvc.method.annotation.ResponseEntityExceptionHandler;
+
+@ControllerAdvice
+public class RestResponseEntityExceptionHandler extends ResponseEntityExceptionHandler {
+
+    @ExceptionHandler({ RepositoryConstraintViolationException.class })
+    public ResponseEntity<Object> handleAccessDeniedException(Exception ex, WebRequest request) {
+        RepositoryConstraintViolationException nevEx = (RepositoryConstraintViolationException) ex;
+
+        String errors = nevEx.getErrors().getAllErrors().stream().map(p -> p.toString()).collect(Collectors.joining("\n"));
+        return new ResponseEntity<Object>(errors, new HttpHeaders(), HttpStatus.NOT_ACCEPTABLE);
+    }
+
+}

spring-data-rest/src/main/java/com/baeldung/models/WebsiteUser.java

@@ -1,4 +1,4 @@
-package com.baeldung;
+package com.baeldung.models;
 
 import javax.persistence.Entity;
 import javax.persistence.GeneratedValue;

spring-data-rest/src/main/java/com/baeldung/repositories/UserRepository.java

@@ -0,0 +1,11 @@
+package com.baeldung.repositories;
+
+import org.springframework.data.repository.CrudRepository;
+import org.springframework.data.rest.core.annotation.RepositoryRestResource;
+
+import com.baeldung.models.WebsiteUser;
+
+@RepositoryRestResource(collectionResourceRel = "users", path = "users")
+public interface UserRepository extends CrudRepository<WebsiteUser, Long> {
+   
+}

spring-data-rest/src/main/java/com/baeldung/validators/WebsiteUserValidator.java

@@ -0,0 +1,33 @@
+package com.baeldung.validators;
+
+import org.springframework.stereotype.Component;
+import org.springframework.validation.Errors;
+import org.springframework.validation.Validator;
+
+import com.baeldung.models.WebsiteUser;
+
+@Component("beforeCreateWebsiteUserValidator")
+public class WebsiteUserValidator implements Validator {
+
+    @Override
+    public boolean supports(Class<?> clazz) {
+        return WebsiteUser.class.equals(clazz);
+    }
+
+    @Override
+    public void validate(Object obj, Errors errors) {
+
+        WebsiteUser user = (WebsiteUser) obj;
+        if (checkInputString(user.getName())) {
+            errors.rejectValue("name", "name.empty");
+        }
+
+        if (checkInputString(user.getEmail())) {
+            errors.rejectValue("email", "email.empty");
+        }
+    }
+
+    private boolean checkInputString(String input) {
+        return (input == null || input.trim().length() == 0);
+    }
+}

spring-data-rest/src/main/test/com/baeldung/validator/SpringDataRestValidatorTest.java

@@ -0,0 +1,100 @@
+package com.baeldung.validator;
+
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.post;
+import static org.springframework.test.web.servlet.result.MockMvcResultHandlers.print;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.content;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.redirectedUrl;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+import static org.springframework.test.web.servlet.setup.MockMvcBuilders.webAppContextSetup;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.SpringApplicationConfiguration;
+import org.springframework.http.MediaType;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+import org.springframework.test.context.web.WebAppConfiguration;
+import org.springframework.test.web.servlet.MockMvc;
+import org.springframework.test.web.servlet.ResultActions;
+import org.springframework.test.web.servlet.ResultMatcher;
+import org.springframework.web.context.WebApplicationContext;
+
+import com.baeldung.SpringDataRestApplication;
+import com.baeldung.models.WebsiteUser;
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+@RunWith(SpringJUnit4ClassRunner.class)
+@SpringApplicationConfiguration(classes = SpringDataRestApplication.class)
+@WebAppConfiguration
+public class SpringDataRestValidatorTest {
+    public static final String URL = "http://localhost";
+
+    private MockMvc mockMvc;
+
+    @Autowired
+    protected WebApplicationContext wac;
+
+    @Before
+    public void setup() {
+        mockMvc = webAppContextSetup(wac).build();
+    }
+
+    @Test
+    public void whenStartingApplication_thenCorrectStatusCode() throws Exception {
+        mockMvc.perform(get("/users")).andExpect(status().is2xxSuccessful());
+    };
+
+    @Test
+    public void whenAddingNewCorrectUser_thenCorrectStatusCodeAndResponse() throws Exception {
+        WebsiteUser user = new WebsiteUser();
+        user.setEmail("john.doe@john.com");
+        user.setName("John Doe");
+
+        mockMvc.perform(post("/users", user).contentType(MediaType.APPLICATION_JSON).content(new ObjectMapper().writeValueAsString(user)))
+        .andExpect(status().is2xxSuccessful())
+        .andExpect(redirectedUrl("http://localhost/users/1"));
+    }
+    
+    @Test
+    public void whenAddingNewUserWithoutName_thenErrorStatusCodeAndResponse() throws Exception {
+        WebsiteUser user = new WebsiteUser();
+        user.setEmail("john.doe@john.com");
+
+        mockMvc.perform(post("/users", user).contentType(MediaType.APPLICATION_JSON).content(new ObjectMapper().writeValueAsString(user)))
+        .andExpect(status().isNotAcceptable())
+        .andExpect(redirectedUrl(null));
+    }
+    
+    @Test
+    public void whenAddingNewUserWithEmptyName_thenErrorStatusCodeAndResponse() throws Exception {
+        WebsiteUser user = new WebsiteUser();
+        user.setEmail("john.doe@john.com");
+        user.setName("");
+        mockMvc.perform(post("/users", user).contentType(MediaType.APPLICATION_JSON).content(new ObjectMapper().writeValueAsString(user)))
+        .andExpect(status().isNotAcceptable())
+        .andExpect(redirectedUrl(null));
+    }
+    
+    @Test
+    public void whenAddingNewUserWithoutEmail_thenErrorStatusCodeAndResponse() throws Exception {
+        WebsiteUser user = new WebsiteUser();
+        user.setName("John Doe");
+        
+        mockMvc.perform(post("/users", user).contentType(MediaType.APPLICATION_JSON).content(new ObjectMapper().writeValueAsString(user)))
+        .andExpect(status().isNotAcceptable())
+        .andExpect(redirectedUrl(null));
+    }
+    
+    @Test
+    public void whenAddingNewUserWithEmptyEmail_thenErrorStatusCodeAndResponse() throws Exception {
+        WebsiteUser user = new WebsiteUser();
+        user.setName("John Doe");
+        user.setEmail("");
+        mockMvc.perform(post("/users", user).contentType(MediaType.APPLICATION_JSON).content(new ObjectMapper().writeValueAsString(user)))
+        .andExpect(status().isNotAcceptable())
+        .andExpect(redirectedUrl(null));
+    }
+
+}