Hot questions for Spring Data REST

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Question:

Currently I have a Spring Boot application using Spring Data REST. I have a domain entity Post which has the @OneToMany relationship to another domain entity, Comment. These classes are structured as follows:

Post.java:

@Entity
public class Post {

    @Id
    @GeneratedValue
    private long id;
    private String author;
    private String content;
    private String title;

    @OneToMany
    private List<Comment> comments;

    // Standard getters and setters...
}

Comment.java:

@Entity
public class Comment {

    @Id
    @GeneratedValue
    private long id;
    private String author;
    private String content;

    @ManyToOne
    private Post post;

    // Standard getters and setters...
}

Their Spring Data REST JPA repositories are basic implementations of CrudRepository:

PostRepository.java:

public interface PostRepository extends CrudRepository<Post, Long> { }

CommentRepository.java:

public interface CommentRepository extends CrudRepository<Comment, Long> { }

The application entry point is a standard, simple Spring Boot application. Everything is configured stock.

Application.java

@Configuration
@EnableJpaRepositories
@Import(RepositoryRestMvcConfiguration.class)
@EnableAutoConfiguration
public class Application {

    public static void main(final String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

Everything appears to work correctly. When I run the application, everything appears to work correctly. I can POST a new Post object to http://localhost:8080/posts like so:

Body: {"author":"testAuthor", "title":"test", "content":"hello world"}

Result at http://localhost:8080/posts/1:

{
    "author": "testAuthor",
    "content": "hello world",
    "title": "test",
    "_links": {
        "self": {
            "href": "http://localhost:8080/posts/1"
        },
        "comments": {
            "href": "http://localhost:8080/posts/1/comments"
        }
    }
}

However, when I perform a GET at http://localhost:8080/posts/1/comments I get an empty object {} returned, and if I try to POST a comment to the same URI, I get an HTTP 405 Method Not Allowed.

What is the correct way to create a Comment resource and associate it with this Post? I'd like to avoid POSTing directly to http://localhost:8080/comments if possible.


Answer:

Assuming you already have discovered the post URI and thus the URI of the association resource (considered to be $association_uri in the following), it generally takes these steps:

  1. Discover the collection resource managing comments:

    curl -X GET http://localhost:8080
    
    200 OK
    { _links : {
        comments : { href : "…" },
        posts :  { href : "…" }
      }
    }
    
  2. Follow the comments link and POST your data to the resource:

    curl -X POST -H "Content-Type: application/json" $url 
    { … // your payload // … }
    
    201 Created
    Location: $comment_url
    
  3. Assign the comment to the post by issuing a PUT to the association URI.

    curl -X PUT -H "Content-Type: text/uri-list" $association_url
    $comment_url
    
    204 No Content
    

Note, that in the last step, according to the specification of text/uri-list, you can submit multiple URIs identifying comments separated by a line break to assign multiple comments at once.

A few more notes on the general design decisions. A post/comments example is usually a great example for an aggregate, which means I'd avoid the back-reference from the Comment to the Post and also avoid the CommentRepository completely. If the comments don't have a lifecycle on their own (which they usually don't in an composition-style relationship) you rather get the comments rendered inline directly and the entire process of adding and removing comments can rather be dealt with by using JSON Patch. Spring Data REST has added support for that in the latest release candidate for the upcoming version 2.2.

Question:

I have an entity as below

Class Person{
String id;
String name;
String numberOfHands;
}

With Spring Data Rest (Gosling Release Train), I'm able to specify

localhost/Person?sort=name,asc

for sorting name name ascending. Now, in a case where I need to sort by numberOfHands descending and name ascending. I'm able to specify

localhost/Person?sort=numberOfHands,name,asc

But, I'm not able to specify

localhost/Person?sort=numberOfHands,desc,name,asc

Is there a way to specify multiple sort order?

Thanks!


Answer:

Solution (tl;dr)

When wanting to sort on multiple fields you simply put the sort parameter multiple times in the URI. For example your/uri?sort=name,asc&sort=numberOfHands,desc. Spring Data is then capable of constructing a Pageable object with multiple sorts.

Explanation

There is not really a defined standard on how to submit multiple values for a parameter in a URI. See Correct way to pass multiple values for same parameter name in GET request.

However there is some information in the Java Servlet Spec which hints on how Java servlet containers parse request parameters.

The getParameterValues method returns an array of String objects containing all the parameter values associated with a parameter name. ... - Java Servlet Spec, section 3.1

The sample further in that section states (although it mixes request and body data)

For example, if a request is made with a query string of a=hello and a post body of a=goodbye&a=world, the resulting parameter set would be ordered a=hello, goodbye, world.

This sample shows that when a parameter (a in the example) is presented multiple times the results will be aggregated into a String[].

Question:

I am developing a Spring Boot application with a Rest interface and a dart fronted.

The XMLHttpRequest does execute a OPTIONS request which is handled totally correct. After this, the final GET ("/products") request is issued and fails:

No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:63343' is therefore not allowed access.

After some debugging I have found the following: The AbstractHandlerMapping.corsConfiguration is populated for all Subclasses except RepositoryRestHandlerMapping. In the RepositoryRestHandlerMapping no corsConfiguration is present / set at creation time and so it won't get recognized as cors path / resource. => No CORS headers attached Could that be the problem? How can I set it?

Configuration classes:

@Configuration
public class RestConfiguration extends RepositoryRestMvcConfiguration {

    @Override
    public void addCorsMappings(CorsRegistry registry) {
        registry.addMapping("/**").allowCredentials(false).allowedOrigins("*").allowedMethods("PUT", "POST", "GET", "OPTIONS", "DELETE").exposedHeaders("Authorization", "Content-Type");
    }

   ...
}

I even tried to set the Cors per annotation:

@CrossOrigin( methods = RequestMethod.GET, allowCredentials = "false")
public interface ProductRepository extends CrudRepository<Product, String> {


}

Raw request headers:

GET /products HTTP/1.1
Host: localhost:8080
Connection: keep-alive
Cache-Control: max-age=0
authorization: Basic dXNlcjpwYXNzd29yZA==
User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Ubuntu Chromium/43.0.2357.130 Chrome/43.0.2357.130 Safari/537.36
Content-Type: application/json
Accept: */*
Referer: http://localhost:63343/inventory-web/web/index.html
Accept-Encoding: gzip, deflate, sdch
Accept-Language: de-DE,de;q=0.8,en-US;q=0.6,en;q=0.4

Raw response headers:

HTTP/1.1 200 OK
Server: Apache-Coyote/1.1
Content-Type: application/hal+json;charset=UTF-8
Transfer-Encoding: chunked
Date: Thu, 30 Jul 2015 15:58:03 GMT

Versions used: Spring Boot 1.3.0.M2 Spring 4.2.0.RC2

What do I miss?


Answer:

Indeed, before Spring Data REST 2.6 (Ingalls) only HandlerMapping instances created by Spring MVC WebMvcConfigurationSupport and controllers annotated with @CrossOrigin were CORS aware.

But now that DATAREST-573 has been fixed, RepositoryRestConfiguration now exposes a getCorsRegistry() for global setup and @CrossOrigin annotations on repositories are also recognized so this is the recommended approach. See https://stackoverflow.com/a/42403956/1092077 answer for concrete examples.

For people that have to stick to Spring Data REST 2.5 (Hopper) or previous versions, I think the best solution is to use a filter based approach. You could obviously use Tomcat, Jetty or this one, but be aware that Spring Framework 4.2 also provides a CorsFilter that use the same CORS processing logic that @CrossOrigin and addCorsMappings(CorsRegistry registry) approaches. By passing an UrlBasedCorsConfigurationSource instance to the CorsFilter constructor parameter, you could easily get something as powerful as Spring native CORS global support.

If you are using Spring Boot (which supports Filter beans), it could be something like:

@Configuration
public class RestConfiguration {

    @Bean
    public FilterRegistrationBean corsFilter() {
        UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
        CorsConfiguration config = new CorsConfiguration().applyPermitDefaultValues();
        source.registerCorsConfiguration("/**", config);
        FilterRegistrationBean bean = new FilterRegistrationBean(new CorsFilter(source));
        bean.setOrder(0);
        return bean;
    }
}

Question:

When I hit the database with PagingAndSortingRepository.findAll(Pageable) I get Page<ObjectEntity>. However, I want to expose DTO's to the client and not entities. I can create DTO just by injecting entity into it's constructor, but how do I map the entities in Page object to DTO's? According to spring documentation, Page provides read-only operations.

Also, Page.map is not possibility, as we don't have support for java 8. How to create the new Page with mapped objects manually?


Answer:

You can still use the Page.map without lambda expressions:

Page<ObjectEntity> entities = objectEntityRepository.findAll(pageable);
Page<ObjectDto> dtoPage = entities.map(new Converter<ObjectEntity, ObjectDto>() {
    @Override
    public ObjectDto convert(ObjectEntity entity) {
        ObjectDto dto = new ObjectDto();
        // Conversion logic

        return dto;
    }
});

Question:

Using Spring Data REST with JPA in version 2.0.2.RELEASE.

How can I disable Hypertext Application Language (HAL) in the JSON ? http://stateless.co/hal_specification.html

I have tried many things already, but to no avail. For example, I have set Accept and Content-type headers to "application/json" instead of "application/hal+json" but I still receive the JSON content with hyper links.

For example, I'd like to get something like:

{
"name" : "Foo",
"street" : "street Bar",
"streetNumber" : 2,
"streetLetter" : "b",
"postCode" : "D-1253",
"town" : "Munchen",
"country" : "Germany",
"phone" : "+34 4410122000",
"vat" : "000000001",
"employees" : 225,
"sector" : {
     "description" : "Marketing",
     "average profit": 545656665,
     "average employees": 75,
     "average profit per employee": 4556
     }
}

Instead of:

{
"name" : "Foo",
"street" : "street Bar",
"streetNumber" : 2,
"streetLetter" : "b",
"postCode" : "D-1253",
"town" : "Munchen",
"country" : "Germany",
"phone" : "+34 4410122000",
"vat" : "000000001",
"employees" : 225,
"_links" : {
     "self" : {
          "href" : "http://localhost:8080/app/companies/1"
     },
     "sector" : {
          "href" : "http://localhost:8080/app/companies/1/sector"
     }
}
}

Thanks for your help.


Answer:

(Hyper)media types

The default settings for Spring Data REST use HAL as the default hypermedia representation format, so the server will return the following for the given Accept headers:

  • No header -> application/hal+json -> HAL
  • application/hal+json -> application/hal+json -> HAL
  • application/json -> application/json -> HAL (this is what the default configures)
  • application/x-spring-data-verbose+json -> application/x-spring-data-verbose+json -> a Spring Data specific format (using links for the links container and content as wrapper for the collection items.

If you configure RepositoryRestConfiguration.setDefaultMediaType(…) to a non-HAL format, the server will return the Spring Data specific JSON format unless you explicitly ask for application/hal+json. Admittedly the configuration option is probably a bit misleading, so I filed DATAREST-294 to improve this. The issue was resolved in 2.1 RC1 (Dijkstra) 2014.

Note that we effectively need a hypermedia format in place to be able to express relations between managed resources and enable discoverability of the server. So there's no way you'll be able to get rid of it completely. This is mostly due to the fact that you could easily crash the server if you expose entities that have bidirectional relationships or make up an enormous object graph.

Inlining related entities

If you never want to have sectors linked to and always inline them, one option is to simply exclude the SectorRepository from being exported as a REST resource in the first place. You can achieve this by annotating the repository interface with @RepositoryRestResource(exported = false).

To get a representation returned as you posted in your lower example have a look at the projections feature introduced in Spring Data REST 2.1 M1. It basically allow you to craft optional views on a resource that can differ from the default one via a simple interface.

You'd basically define an interface:

@Projection(name = "foo", types = YourDomainClass.class)
interface Inlined {

  // list all other properties

  Sector getSector();
}

If you either put this interface into a (sub)package of your domain class or manually register it via RepositoryRestConfiguration.projectionConfiguration() the resources exposing YourDomainClass will accept a request parameter projection so that passing in foo in this example would render the inlined representation as you want it.

This commit has more info on the feature in general, this commit has an example projection defined.

Question:

I'm trying to get Kotlin working with jsr 303 validation on a spring-data-rest project.

Given the following data class declarartion :

@Entity data class User(
    @Id 
    @GeneratedValue(strategy = javax.persistence.GenerationType.AUTO)
    var id: Long? = null,

    @Size(min=5, max=15)
    val name: String
)

The @Size annotation has no effect here, making me able to save a user with a name of 1 character. It works well when executing the very same example but in a Java class instead of Kotlin.

This makes me think of a Kotlin problem.

Thanks in advance for you help !


Answer:

You need to use Annotation use-site targets since the default for a property declared in the constructor is to target the annotation on the constructor parameter instead of the getter (which will be seen by JavaBeans compliant hosts) when there are multiple options available. Also using a data class might be inappropriate here (see note at end).

@Entity data class User(
    @Id
    @GeneratedValue(strategy = javax.persistence.GenerationType.AUTO)
    var id: Long? = null,

    @get:Size(min=5, max=15) // added annotation use-site target here
    val name: String
)

The property target from the Kotlin docs may look tempting, but it can only be seen from Kotlin and not Java. Usually get does the trick, and it is not needed on the bean set.

The docs describe the process as:

If you don’t specify a use-site target, the target is chosen according to the @Target annotation of the annotation being used. If there are multiple applicable targets, the first applicable target from the following list is used:

  • param
  • property
  • field

And the @Size annotation is:

@Target(value={METHOD,FIELD,ANNOTATION_TYPE,CONSTRUCTOR,PARAMETER})

Therefore since PARAMETER is a valid target, and multiple targets are available (parameter, field, method [get/set]) it choses PARAMETER which is not what you want. Therefore for a JavaBean host to see the property it will look for the getter (properties are defined by the getter/setter and not the backing field).

In one of the Java samples, it shows:

public class Book {
    private String title;
    private String description;

    // ...

    @NotEmpty(groups={FirstLevelCheck.class, Default.class})
    @Size(max=30)
    public String getTitle() {
        return title;
    }

    // ...
}

Which matches our usage of having it on the getter. If it were to be on the field like some of the validation annotations show, see the field use-site target. Or if the field must also be publicly accessible, see the @JvmField annotation in Kotlin.

NOTE: As mentioned in notes from others, you should likely consider NOT using a data class for entities if they use an auto-generated ID since it will not exist for new objects the same as for retrieved objects; and a data class will generate equals and hashCode to include all fields including the ones it should not. You can read guidance about this from the Hibernate docs.

Question:

I am using spring-data-rest to expose entities as (paged) rest resources. Everything works fine, but when I request data via RestTemplate, I get an useless HATEOAS JSON (which I didn't ask for). The JSON seems to be a PagedResources. I could live with that, but the JSON isn't converted into an object correctly. There is no content inside.

Repository:

@RepositoryRestResource(collectionResourceRel = "people", path = "people")
public interface PersonRepository extends PagingAndSortingRepository<Person, Long>
{
    List<Person> findByLastName(@Param("name") String name);
}

Client:

public List<Person> getPersons()
{
    RestTemplate rt = new RestTemplate();
    System.out.println(rt.getForObject(URL, PagedResources.class).getContent().size());
    System.out.println(rt.getForObject(URL, PagedResources.class).getLinks().size());
    System.out.println(rt.getForObject(URL, PagedResources.class).getMetadata().getTotalElements());
    return new ArrayList<Person>(rt.getForObject(URL, PagedResources.class).getContent()); // <-- empty
}

System.out:

0 // getContent().size()
4 // getLinks().size()
2 // getTotalElements()

curl:

C:\...>curl http://localhost:8080/spring-jsf-rest/rest/people
{
  "_links" : {
    "self" : {
      "href" : "http://localhost:8080/spring-jsf-rest/rest/people{?page,size,sort}",
      "templated" : true
    },
    "search" : {
      "href" : "http://localhost:8080/spring-jsf-rest/rest/people/search"
    }
  },
  "_embedded" : {
    "people" : [ {
      "firstName" : "John",
      "lastName" : "Rambo",
      "_links" : {
        "self" : {
          "href" : "http://localhost:8080/spring-jsf-rest/rest/people/1"
        }
      }
    }, {
      "firstName" : "Chuck",
      "lastName" : "Norris",
      "_links" : {
        "self" : {
          "href" : "http://localhost:8080/spring-jsf-rest/rest/people/2"
        }
      }
    } ]
  },
  "page" : {
    "size" : 20,
    "totalElements" : 2,
    "totalPages" : 1,
    "number" : 0
  }
}

It seems like _embedded is not mapped correctly to content?!


Answer:

As you've discovered correctly, PagedResources does not have an _embedded property, that's why you don't get the content property populated.

This dilemma can be solved in two different ways:

  1. Providing a type that matches the representation in the first place. Thus, craft a custom class and either stick to the property names of the representation or customize it using Jackson annotations etc.

  2. Set up a custom MappingJackson2HttpMessageConverter and customize the ObjectMapperto get the Jackson2HalModule configured that Spring HATEOAS ships out of the box.

    ObjectMapper mapper = new ObjectMapper();
    mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
    mapper.registerModule(new Jackson2HalModule());
    
    MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();
    converter.setSupportedMediaTypes(MediaType.parseMediaTypes("application/hal+json"));
    converter.setObjectMapper(mapper);
    
    RestTemplate template = new RestTemplate(Collections.<HttpMessageConverter<?>> singletonList(converter));
    

Question:

Is it possible to integrate Spring managed Hibernate interceptors (http://docs.jboss.org/hibernate/orm/4.3/manual/en-US/html/ch14.html) in Spring Boot?

I'm using Spring Data JPA and Spring Data REST and need an Hibernate interceptor to act on an update of a particular field on an entity.

With standard JPA events it's not possible to get the old values, and hence I think I need to use the Hibernate interceptor.


Answer:

There's not a particularly easy way to add a Hibernate interceptor that is also a Spring Bean but you can easily add an interceptor if it's manged entirely by Hibernate. To do that add the following to your application.properties:

spring.jpa.properties.hibernate.ejb.interceptor=my.package.MyInterceptorClassName

If you need the Interceptor to also be a bean you can create your own LocalContainerEntityManagerFactoryBean. The EntityManagerFactoryBuilder from Spring Boot 1.1.4 is a little too restrictive with the generic of the properties so you need cast to (Map), we'll look at fixing that for 1.2.

@Bean
public LocalContainerEntityManagerFactoryBean entityManagerFactory(
        EntityManagerFactoryBuilder factory, DataSource dataSource,
        JpaProperties properties) {
    Map<String, Object> jpaProperties = new HashMap<String, Object>();
    jpaProperties.putAll(properties.getHibernateProperties(dataSource));
    jpaProperties.put("hibernate.ejb.interceptor", hibernateInterceptor());
    return factory.dataSource(dataSource).packages("sample.data.jpa")
            .properties((Map) jpaProperties).build();
}

@Bean
public EmptyInterceptor hibernateInterceptor() {
    return new EmptyInterceptor() {
        @Override
        public boolean onLoad(Object entity, Serializable id, Object[] state,
                String[] propertyNames, Type[] types) {
            System.out.println("Loaded " + id);
            return false;
        }
    };
}

Question:

I've been working on a RESTful webservice with spring-data. A few days ago a special spring-data jpa REST framework was released.

Now I noticed the ability to use @Version with this framework. Is this version generated by itself or do you need to do this manually?

And is it possible to use @Version on it's own? (So that I don't have to change anything to my existing repositories/domain etc..)

And do I need to do some extra configuration to make use of @Version?


Answer:

It's been a while since I posted this question but I've figured it out. I'll explain what I did so that it might be helpful to someone else.

The annotation @Version is a javax.persistence interface and not the spring-data rest jpa framework as i mentioned earlier.

If you want to make use of @Version you need to create an version field in your domain object like so:

@Version
@Column(name = "VERSION")
private long version;

If you're using hibernate it will automatically pickup the annotation and it will create a "version" row in your (in my case MySql) table. Every time a record gets updated, hibernate will increment the counter with 1.

Now why is this something you want? Well the reason why you might wanna use this is because it decreases the chance that your clients are working with stale data. Whenever a client retrieves information from you a version is provided with the data he requested. e.g.

{                       <-- School entity -->
    "id": 1,
    "version": 0,                 
    "name": "De regenboog",
    "street": "Plantaanstraat",
    "number": "2",
    "zipCode": "1234AS",
    "city": "Amsterdam"
}

Now if a client wants to change some information about this specific record it sends the new information along with the version value. In this case let's change the name of the school.

 {                       <-- School entity -->
    "id": 1,
    "version": 0,                 
    "name": "Stackoverflow",
    "street": "Plantaanstraat",
    "number": "2",
    "zipCode": "1234AS",
    "city": "Amsterdam"
 }

Hibernate comes up with a query with your information and adds an extra 'where' clause to check the version. update .... where id = 1 and version = 0. Now if the row is updated it means you provided the right version and no one else has changed that specific information between the time you requested the information, changed it and sent it back. Nice right?

Now what if the row isn't updated? It means someone else updated that row while you were taking a quick bathroom break after you requested the information. It means your version is outdated! What needs to happen now is really use case specific so I won't go into details about that :)

Hope someone can use this piece of information!

Thanks all

Question:

I'm using spring data (mongoDb) and I've got my repository:

public interface StoriesRepository extends PagingAndSortingRepository<Story, String> {}

Then i have a controller:

@RequestMapping(method = RequestMethod.GET)
public ResponseEntity<Page<StoryResponse>> getStories(Pageable pageable) {
    Page<StoryResponse> stories = storiesRepository.findAll(pageable).map(StoryResponseMapper::toStoryResponse);
    return ResponseEntity.ok(stories);
}

Everything works fine, but I can't consume my endpoint using RestTemplate getForEntity method:

def entity = restTemplate.getForEntity(getLocalhost("/story"), new TypeReference<Page<StoryResponse>>(){}.class)

What class should I provide to successfully deserialize my Page of entities?


Answer:

new TypeReference<Page<StoryResponse>>() {}

The problem with this statement is that Jackson cannot instantiate an abstract type. You should give Jackson the information on how to instantiate Page with a concrete type. But its concrete type, PageImpl, has no default constructor or any @JsonCreators for that matter, so you can not use the following code either:

new TypeReference<PageImpl<StoryResponse>>() {}

Since you can't add the required information to the Page class, It's better to create a custom implementation for Page interface which has a default no-arg constructor, as in this answer. Then use that custom implementation in type reference, like following:

new TypeReference<CustomPageImpl<StoryResponse>>() {}

Here are the custom implementation, copied from linked question:

public class CustomPageImpl<T> extends PageImpl<T> {
    private static final long serialVersionUID = 1L;
    private int number;
    private int size;
    private int totalPages;
    private int numberOfElements;
    private long totalElements;
    private boolean previousPage;
    private boolean firstPage;
    private boolean nextPage;
    private boolean lastPage;
    private List<T> content;
    private Sort sort;

    public CustomPageImpl() {
        super(new ArrayList<>());
    }

    @Override
    public int getNumber() {
        return number;
    }

    public void setNumber(int number) {
        this.number = number;
    }

    @Override
    public int getSize() {
        return size;
    }

    public void setSize(int size) {
        this.size = size;
    }

    @Override
    public int getTotalPages() {
        return totalPages;
    }

    public void setTotalPages(int totalPages) {
        this.totalPages = totalPages;
    }

    @Override
    public int getNumberOfElements() {
        return numberOfElements;
    }

    public void setNumberOfElements(int numberOfElements) {
        this.numberOfElements = numberOfElements;
    }

    @Override
    public long getTotalElements() {
        return totalElements;
    }

    public void setTotalElements(long totalElements) {
        this.totalElements = totalElements;
    }

    public boolean isPreviousPage() {
        return previousPage;
    }

    public void setPreviousPage(boolean previousPage) {
        this.previousPage = previousPage;
    }

    public boolean isFirstPage() {
        return firstPage;
    }

    public void setFirstPage(boolean firstPage) {
        this.firstPage = firstPage;
    }

    public boolean isNextPage() {
        return nextPage;
    }

    public void setNextPage(boolean nextPage) {
        this.nextPage = nextPage;
    }

    public boolean isLastPage() {
        return lastPage;
    }

    public void setLastPage(boolean lastPage) {
        this.lastPage = lastPage;
    }

    @Override
    public List<T> getContent() {
        return content;
    }

    public void setContent(List<T> content) {
        this.content = content;
    }

    @Override
    public Sort getSort() {
        return sort;
    }

    public void setSort(Sort sort) {
        this.sort = sort;
    }

    public Page<T> pageImpl() {
        return new PageImpl<>(getContent(), new PageRequest(getNumber(),
                getSize(), getSort()), getTotalElements());
    }
}