Ignoring Nested properties in Jackson OnDemand - spring

I am working on a spring boot application with Hibernate as ORM and Jackson as JSON serialiser .
I have three model objects and CRUD operations for all three models.
Class Student{
private Teacher teacher; // Teacher of the student — to be fetched eagerly
+Getter/Setter
}
class Teacher {
private List<Subject> subject; // List of subjects associated to that user— to be fetched eagerly
+Getter/Setter
}
class Subject {
private long subjectId
//Other subject properties
+ Getter/Setter
}
Whenever I trigger a get request for student info I get the teacher info which is correct where as I also receive Subject info as well which is unnecessary for me. In the same time when I request for Teacher info, I need Subject info should be associated to that for sure. If I use #JsonBackReference for subject I am losing it all the time. I am not sure how to achieve this.
Thanks in advance for your help!!

You can also annotate like this
Class Student{
#JsonIgnoreProperties("subject")
private Teacher teacher; // Teacher of the student — to be fetched eagerly
}

You can use JSON Views
From the spring blog:
public class View {
interface Summary {}
}
public class User {
#JsonView(View.Summary.class)
private Long id;
#JsonView(View.Summary.class)
private String firstname;
#JsonView(View.Summary.class)
private String lastname;
private String email;
private String address;
private String postalCode;
private String city;
private String country;
}
public class Message {
#JsonView(View.Summary.class)
private Long id;
#JsonView(View.Summary.class)
private LocalDate created;
#JsonView(View.Summary.class)
private String title;
#JsonView(View.Summary.class)
private User author;
private List<User> recipients;
private String body;
}
and in the controller
#RestController
public class MessageController {
#Autowired
private MessageService messageService;
#JsonView(View.Summary.class)
#RequestMapping("/")
public List<Message> getAllMessages() {
return messageService.getAll();
}
#RequestMapping("/{id}")
public Message getMessage(#PathVariable Long id) {
return messageService.get(id);
}
}
PS: No link to http://fasterxml.com/ as it's currently down.

Related

how to properly design a controller and a jsp page for an entity that has three keys, two external and one internal?

I'm trying to make a Spring MVC application.I have 4 entities(Company,Pass_in_trip,Passenger,Trip) Pass_in_trip has 3 keys consisting of Passenger, Trip and Timestamp, I don't know how to properly issue a key and how to transfer it through the jsp page to the controller, and how to issue the controller itself, can anyone tell me?and also an interesting question is how to make a request to the database to search for a record using three keys.
Thanks
here's what I was able to write at the moment, see if there are any errors somewhere
#Entity
#Table(name="company")
public class Company implements Serializable {
#Id
#GeneratedValue(strategy = IDENTITY)
#Column(name="id_comp")
private int id_comp;
#Column(name="name")
private String name;
//Getters and Setters
#Entity
#Table (name="pass_in_trip")
public class Pass_in_trip implements Serializable {
#EmbeddedId
private KeysPass_in_trip key=new KeysPass_in_trip();
#Column(name="place")
private String place;
//Getters and Setters
#Embeddable
public class KeysPass_in_trip implements Serializable{
#NotNull
#JoinColumn(name="date")
private Timestamp date=new Timestamp(System.currentTimeMillis());
#OneToOne(cascade = CascadeType.ALL)
#JoinColumn(name = "id_psg")
private Passenger id_psg=new Passenger();
#OneToOne(cascade = CascadeType.ALL)
#JoinColumn(name = "trip_no" )
private Trip trip_no=new Trip();
//Getters and Setters
//#Override hashCode and equals
#Entity
#Table(name="passenger")
public class Passenger implements Serializable {
#Column(name="name")
private String name;
#NotNull
#Id
#Column(name="id_psg")
#GeneratedValue(strategy = IDENTITY)
private int id_psg;
//Getters and Setters
#Entity
#Table(name="trip")
public class Trip implements Serializable {
#NotNull
#Id
#Column(name="trip_no")
private int trip_no;
#ManyToOne(cascade = CascadeType.MERGE)
#JoinColumn(name = "id_comp")
private Company comp=new Company();
#Column(name="plane")
private String plane;
#Column(name="town_from")
private String town_from;
#Column(name="town_to")
private String town_to;
#Column(name="time_out")
private Timestamp time_out;
#Column(name="time_in")
private Timestamp time_in;
//Getters and Setters
Conroller
#Controller
#RequestMapping("/pass_in_trip/")
public class Aero_Controller_Pass_in_trip {
#Autowired
private Aero_DAO service;
public void setService(Aero_DAO service) {
this.service = service;
}
#RequestMapping(method=RequestMethod.GET)
public String list(Model uiModel) {
List <Pass_in_trip> pass_in_trip=service.findallPass_in_trip();
uiModel.addAttribute("pass_in_trip",pass_in_trip);
return "/pass_in_trip/list";
}
#PreAuthorize("hasRole('ROLE_Admin')")
#RequestMapping(value="delete/{id}",method=RequestMethod.GET)
public String delete(#PathVariable("id")int id, Model uiModel) {
if(service.findByIdPass_in_Trip(id)!=null)
service.delete_Pass_in_trip(id);
return "redirect:/pass_in_trip/";
}
#PreAuthorize("hasRole('ROLE_Admin')")
#RequestMapping(value="update/{id}",method=RequestMethod.GET)
public String updateform(#PathVariable("id")int id, Model uiModel) {
System.out.println("upform");
uiModel.addAttribute("pass_in_trip",service.findByIdPass_in_Trip(id));
System.out.println("upform2");
return "/pass_in_trip/edit";
}
#RequestMapping(value="update/0",method=RequestMethod.GET)
public String newform(Model uiModel) {
System.out.println("Привет!");
return "/pass_in_trip/edit";
}
#PreAuthorize("hasRole('ROLE_Admin')")
#RequestMapping(value="update/{id}",method = RequestMethod.POST)
public String update(Pass_in_trip pass_in_trip,BindingResult bindingResult,Model uiModel,HttpServletRequest httprervletrequest , RedirectAttributes redirectatributes) {
if (bindingResult.hasErrors()) {
uiModel.addAttribute("pass_in_trip", pass_in_trip);
return "pass_in_trip/update";}
service.save(pass_in_trip);
return "redirect:/pass_in_trip/";
}
}
List.jsp
interested in this part:
<s:authorize access="hasRole('ROLE_Admin')">
<td> To change </td>
<td> Delete </td>
</s:authorize>

I don't know why the double values are displayed in postman. Is the my code correct?

This is my Book class:
#Entity
#Table(name="book")
public class Book {
#JsonIgnoreProperties({"hibernateLazyInitializer", "handler"})
#ManyToOne(targetEntity=Category.class,cascade=CascadeType.ALL,fetch=FetchType.LAZY)
#JoinColumn(name="CategoryId")
public Category category;
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
#Column(length=10)
private int book_id;
#Column(length=128)
private String title;
#Column(length=64)
private String author;
#Column(length=200)
private String description;
#Column(length=10)
private int ISBN;
#Column(length=10)
private float price;
private Date published_Date;
#Lob
#Column
#Basic(fetch = FetchType.LAZY)
private byte[] icon;
//getter and setter
}
This is my Category class:
#Entity
#Table(name="category1")
public class Category {
#Id
#Column(length=12)
#GeneratedValue(strategy=GenerationType.AUTO)
public int CategoryId;
#Column(length=50)
public String CategoryName;
//#JsonBackReference
#OneToMany(mappedBy="category")
private List<Book> books = new ArrayList<Book>();
//getter and setter
}
The relationship between them is one to many.
This is my Category Service class
#Service
#Transactional
public class AdminServiceImpl implements AdminService {
#Autowired
private CategoryDao dao;
#Autowired
private BookDao dao1;
#Override
public List<Category> getAllCategory(){
return dao.findAll();
}
}
My Controller class
#RestController
#RequestMapping("/bookstore")
public class CategoryController {
#Autowired
private AdminService service;
#GetMapping("/GetAllCategory")
private ResponseEntity<List<Category>> getAllCategory() {
List<Category> catlist = service.getAllCategory();
return new ResponseEntity<List<Category>>(catlist, new HttpHeaders(), HttpStatus.OK);
}
}
My category table already has data.When i try to display them it is showing double values.
Displaying values using Postman
The Category table in the Database: Database table
Jackson's ObjectMapper uses the Java bean pattern and it expects the following
public class Foo {
public Object bar;
public Object getBar() {...}
public void setBar(Object bar) {...}
}
The getters and setters start with get and set, respectively, followed by the corresponding field name with its first letter capitalized.
Change
CategoryId to categoryId (first letter lowercase)
and
CategoryName to categoryName

Spring Framework Responses from POST

What is the standard object design for accepting a POST request from a client, saving the record to the database, and then returning a response back to the client? I'm working with the Spring framework.
Should I be sending back the entity and hiding properties that aren't necessary for the response?
#RestController
public class SomeController {
private final SomeService service;
#PostMapping(value = "/post/new", produces = MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity<SomeEntity> post(#RequestBody final SomeEntity someEntity) {
SomeEntity savedEntity = service.save(someEntity);
return ResponseEntity.ok(savedEntity);
}
}
#Entity
#Table(name = "posts")
public class SomeEntity {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#Column(name = "title")
private String title;
#Column(name = "body")
#JsonIgnore
private String body;
#JsonIgnore
#Column(name = "deleted_ind")
private boolean deleted;
#JsonIgnore
#Column(name = "author")
private String author;
#Column(name = "created_at")
private LocalDateTime createdAt;
}
or would I accept some sort of POST request object that I convert to an entity, then re-assemble the entity into a response?
#JsonIgnoreProperties(ignoreUnknown = true)
public class SomePostRequestResource {
private String title;
private String body;
private String createdAt;
}
#RequiredArgsConstructor
#RestController
public class SomeController {
private final SomeService service;
private final SomeResourceAssembler resourceAssembler;
#PostMapping(value = "/post/new", produces = MediaType.APPLICATION_JSON_VALUE)
public ResponseEntity<SomePostRequestResource> post(
#RequestBody final SomePostRequestResource someResource
) {
SomeEntity savedEntity = service.convertToEntityAndSave(someResource);
SomePostRequestResource response = resourceAssembler.toResource(savedEntity);
return ResponseEntity.ok(response);
}
}
But then maybe I only want to send back the createdAt, would I hide the other properties in the SomePostRequestResource, or do I need another object to represent the response, which only has the property I want to send back?
I would also appreciate any book or article suggestions related to desigining objects for use with a RESTful API. I have seen articles concerning how to design and name the endpoints, but not so many concerning how to design the objects on the backend.
I would recommend you create a DTO class for the incoming/outgoing data containing the filed that are set/viewable by the client like:
public class SomeEntityIncomingDto {
private String title;
....
}
public class SomeEntityOutgoingDto {
private Long id;
private String title;
....
}
On the other hand, You won't need to map your persistence entities to DTOs and vice versa manually, you can use a library like ModelMapper or MapStruct that handles the conversion automatically.

neo4j RelationshipEntity not created

I'm having issues getting a neo4j RelationshipEntity persisted with Spring Boot. I'm using spring-boot-starter-data-neo4j (2.1.0.RELEASE), and the neo4j docker image tagged 3.4.9.
I have a simple NodeEntity, which contains a collection for the RelationshipEntity:
#NodeEntity
public class Book {
#Id
#GeneratedValue
private Long id;
private String name;
public Book() {}
public Book(String name) {
this.name = name;
}
#Relationship(type = "PURCHASED_WITH", direction = "OUTGOING")
private Set<BookPurchase> purchases = new HashSet<>();
// getters and setters follow
}
I have another NodeEntity, which also contains a collection for the relationship entity:
#NodeEntity
public class CreditCard {
#Id
#GeneratedValue
private Long id;
private String number;
#DateString(value = "yyyy-MM-dd")
private Date expiryDate;
public CreditCard() {}
public CreditCard(String number, Date expiryDate) {
this.number = number;
this.expiryDate = expiryDate;
}
#Relationship(type = "PURCHASED_WITH", direction = "INCOMING")
private Set<BookPurchase> purchases = new HashSet<BookPurchase>();
// getters and setters follow
}
I have the RelationshipEntity, which adds references to both NodeEntity classes in the constructor:
#RelationshipEntity(type = "PURCHASED_WITH")
public class BookPurchase {
#Id
#GeneratedValue
private long id;
#DateString("yyyy-MM-dd")
Date purchaseDate;
#StartNode
private Book book;
#EndNode
private CreditCard card;
public BookPurchase(){}
public BookPurchase(CreditCard card, Book book, Date purchaseDate) {
this.card = card;
this.book = book;
this.purchaseDate = purchaseDate;
this.card.getPurchases().add(this);
this.book.getPurchases().add(this);
}
// getters and setters follow
}
And finally I have the Spring controller tying everything together:
#RestController
public class ExamplesController {
#Autowired
CreditCardRepository creditCardRepository;
#PostMapping(value="/purchases")
public String createPurchases() {
CreditCard card = new CreditCard("11111", new GregorianCalendar(2018, Calendar.FEBRUARY, 12).getTime());
Book book1 = new Book("of mice and men");
BookPurchase purchase1 = new BookPurchase(card,book1,new GregorianCalendar(2018, Calendar.MARCH, 15).getTime());
creditCardRepository.save(card);
return "Successfully created entities";
}
}
Whenever I try to curl -X POST http://localhost:8080/purchases, I just see the following in the neo4j browser - the RelationshipEntity is not persisted, only the nodes.
Can anyone assist?
Thanks to Gerrit Meier for answering this one. My RelationshipEntity was using the primitive long instead of the object/wrapper Long. Complete details here: https://community.neo4j.com/t/neo4j-relationshipentity-not-persisted/3039

Why the record is posted twice in the database?

Can you tell me, why the record is posted twice in the database. I think. this happens because I use save() method. But shouldn't I save the master-entity and dependent-entity separately?
Controller method:
#RequestMapping(value = "/addComment/{topicId}", method = RequestMethod.POST)
public String saveComment(#PathVariable int topicId, #ModelAttribute("newComment")Comment comment, BindingResult result, Model model){
Topic commentedTopic = topicService.findTopicByID(topicId);
commentedTopic.addComment(comment);
// TODO: Add a validator here
if (!comment.isValid() ){
return "//";
}
// Go to the "Show topic" page
commentService.saveComment(comment);
return "redirect:../details/" + topicService.saveTopic(commentedTopic);
}
Services:
#Service
#Transactional
public class CommentService {
#Autowired
private CommentRepository commentRepository;
public int saveComment(Comment comment){
return commentRepository.save(comment).getId();
}
}
#Service
#Transactional
public class TopicService {
#Autowired
private TopicRepository topicRepository;
public int saveTopic(Topic topic){
return topicRepository.save(topic).getId();
}
}
Model:
#Entity
#Table(name = "T_TOPIC")
public class Topic {
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
private int id;
#ManyToOne
#JoinColumn(name="USER_ID")
private User author;
#Enumerated(EnumType.STRING)
private Tag topicTag;
private String name;
private String text;
#OneToMany(fetch = FetchType.EAGER, mappedBy = "topic", cascade = CascadeType.ALL)
private Collection<Comment> comments = new LinkedHashSet<Comment>();
}
#Entity
#Table(name = "T_COMMENT")
public class Comment
{
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
private int id;
#ManyToOne
#JoinColumn(name="TOPIC_ID")
private Topic topic;
#ManyToOne
#JoinColumn(name="USER_ID")
private User author;
private String text;
private Date creationDate;
}
In this concrete case, you do not need to save the master and the client.
Saving the master or the client would be enough (with this concrete mapping)
But I think the main problem is that you do not have a good equals method in your Comment so your ORM Provider think that there are two different comments, and therefore store them twice.

Resources