I'm using Spring Data JPA but I'm stuck on how to create a query based on who a user has chat history with.
I have the two objects of which Message is an entity while Chat-Message is not.
You can take a look from both classes and guide me on how I can create a spring data JPA query that queries certain users conversations with other users:
#Entity
public class Message {
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
Long id;
String message;
#ManyToOne
#JoinColumn(name="fromUser",nullable=false)
private User fromUser;
#ManyToOne
#JoinColumn(name="toUser",nullable=false)
private User toUser;
public Message() { }
public Message(User fromUser, User toUser, String message) {
this.fromUser=fromUser;
this.toUser=toUser;
this.message=message;
}
public Long getId() {
return id;
}
// getters and setters
}
public class ChatMessage {
Long id;
String message;
String sender;
String username;
Long senderId;
public ChatMessage() { }
// getters and setters
public ChatMessage(Message m, Boolean isReply) {
this.sender = m.getFromUser().getFirstname() + " " + m.getFromUser().getLastname();
this.message = m.getMessage();
this.senderId = m.getFromUser().getId();
this.id = m.getId();
}
}
My possible endpoint:
#RequestMapping(value="/conversations",produces = "application/json")
#ResponseBody
public List<Message> myMessages(Principal principal){
String thisUser=principal.getName();
User user=userServiceImpl.findByUsername(thisUser);
// List<Message>messages=messageServiceImpl.finddAll();
List<Message> messages=messageServiceImpl.fetchMessages(user.getId());
return messages;
}
Note that Chat-Message is just an object class for carrying WebSocket messages. My Message Repo:
public interface MessageRepository extends JpaRepository<Message,Long>{
}
Image: [1]: https://i.stack.imgur.com/hVbP3.png
It's not really clear what exactly you need here, and what messageServiceImpl does, for instance. But, maybe this will be useful:
public interface MessageRepository extends JpaRepository<Message, Long> {
// if we get all messages your user sent or received - would it be
// what you mean here a "conversation" ?
List<Message> findByFromUserIdOrToUserId(Long id);
// or you can use #Query to achieve the same
#Query("select m from Message m where m.fromUser.id = :id or m.toUser.id = :id")
List<User> findMessagesForUser(Long id);
}
You can also find more details of how to create queries using Spring Data in their official docs.
Related
I have a Spring Boot Rest API. I want to create users and set a unique constraint on their email and username. That works well so far. Here are the main classes and methods:
#Entity
#NoArgsConstructor
#Getter
#Setter
public class User {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
#Column(unique = true)
#NotNull
private String email;
#Column(unique = true)
#NotNull
private String username;
#NotNull
private String password;
public User(String email, String username, String password) {
this.email = email;
this.password = password;
this.username = username;
}
}
#Data
#NoArgsConstructor
#AllArgsConstructor
public class SignupRequest {
#NotNull
private String email;
#NotNull
private String username;
#NotNull
private String password;
}
#CrossOrigin(value = "*")
#PostMapping("/signup")
public ResponseEntity<?> signup(#Valid #RequestBody SignupRequest signupRequest) {
signupService.signup(signupRequest);
return ResponseEntity.ok().build();
}
#Service
public class SignupServiceImpl implements SignupService {
#Override
public void signup(SignupRequest signupRequest) throws MessagingException, UnsupportedEncodingException {
User user = new User();
User user = new User(signupRequest.getEmail(), signupRequest.getUsername(), signupRequest.getPassword());
user = userRepository.save(user);
}
}
#Repository
#Component
public interface UserRepository extends CrudRepository<User, Long> {}
Now, the thing is, when I send a POST request to that endpoint with a username or email that already exists, I just get the http response 500 Internal Server Error. But I want to return a different status code and some Error message indicating that the email/username already exists.
Now two questions:
How can I modify the response globally? I could surround the userRepository.save(user) method with a try catch block, but I would have to do that in all the methods where I save a user separately. Can I define something like that globally?
The userRepository.save(user) method just returns a. JdbcSQLIntegrityConstraintViolationException with a pretty verbose message. Is there a way to clearly determine WHAT exactly went wrong (unique username constraint failed, unique email constraint failed, ...)? I could check if a user with that username or email exists by writing a method in the userRepository, but that looks like a lot of unnecessary sql queries to me. Is there a better way?
To answer your first question, You can handle exception globally via spring exception handling mechanism. You could use spring ControllerAdvice. Here you can set generic error response and custom http code. Here is an example of ControllerAdvice
#ControllerAdvice
public class CustomExceptionHandler extends ResponseEntityExceptionHandler
{
#ExceptionHandler(UserNotFoundException.class)
public final ResponseEntity<ErrorResponse> handleUserNotFoundException(UserNotFoundException ex, WebRequest request) {
String details = ex.getLocalizedMessage();
ErrorResponse error = new ErrorResponse(ApplicationConstants.RECORD_NOT_FOUND, details);
return new ResponseEntity<>(error, HttpStatus.NOT_FOUND);
}
#ExceptionHandler(Exception.class)
public final ResponseEntity<ErrorResponse> handleAllExceptions(Exception ex, WebRequest request) {
String details = ex.getLocalizedMessage();
ErrorResponse error = new ErrorResponse(ApplicationConstants.SERVER_ERROR, details);
return new ResponseEntity<>(error, HttpStatus.INTERNAL_SERVER_ERROR);
}
}
public class ErrorResponse
{
public ErrorResponse(String message, String details) {
super();
this.message = message;
this.details = details;
}
private String message;
private String details;
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
public String getDetails() {
return details;
}
public void setDetails(String details) {
this.details = details;
}
}
Now about second question you can loop through all the cause and check unique constraint name to find out what exception violated. But better approach would be to check first and if found then throw error.
I need to remove cart object from json, but only in one controller method and that is:
#GetMapping("/users")
public List<User> getUsers() {
return userRepository.findAll();
}
User
#Entity
public class User {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
#NotBlank(message = "Name cannot be empty")
private String name;
#OneToOne
private Cart cart;
}
Cart
#Entity
public class Cart {
#Id
private String id = UUID.randomUUID().toString();
#OneToMany
private List<CartItem> cartItems = new ArrayList<>();
#OneToOne
#JsonIgnore
#OnDelete(action = OnDeleteAction.CASCADE)
private User user;
}
I have done it with simple solution so i loop trough all users, and set their cart to null,and then anotated user entity with #JsonInclude(JsonInclude.Include.NON_NULL)
But i dont think this is propper solution, so im searching for some better solution..
How am i able to do this?
Thanks...
You can create DTO (data transfer object) class like this:
#Data
public class UsersDto {
private Integer id;
private String name;
public UsersDto(User user) {
this.id = user.id;
this.name= user.name;
}
}
and than create List<UsersDto>
#GetMapping("/users")
public List<UsersDto> getUsers() {
List<User> users = userRepository.findAll();
return users
.stream()
.map(o -> new UsersDto(o))
.collect(Collectors.toList());
}
You should use Data Projection.
In your use case, you can use an interface projection:
public interface CartlessUser {
Integer getId();
String getName();
}
And In your repository:
public interface UserRepository extends JpaRepository<User, Integer> {
List<CartlessUser> findAllBy();
}
The interface projection will help generate the sql query for only selecting the id, name fields. This will save you from fetching the Cart data when you're just going to throw it away anyways.
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.
I am using spring data jpa with hibernate
This is my dao interface
#Repository
public interface IUserDAO extends JpaRepository<User, Integer>{
User findByUsername( final String username );
}
This is my User class
Entity
#Table(name="USER")
public class User {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name="ID", nullable = false)
private int id;
#Column(name="USERNAME", nullable = false)
private String username;
#Column(name="NAME", nullable = false)
private String name;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
This is my UserImplClass
This is my UserImplClass{
#Autowired
private IUserDAO iUserDAO;
public String findUserByUserName(String username) {
User user =iUserDAO.findByUsername(username);
Convert user to json object from framework level automatically
// i can add my one implemenation of converting user to json here ,but i want to achieve it from framework so that my code is not scattered on every service level
return "jsonStringOfUserObject"
}
Is it possible with spring data jpa with hibernate so that i do not have to write code for converting java object to json string in every service level?
I am using spring ,therefore i want to achieve it from spring .
You have two options to do what you want:
1) If you plan on returning this Object as an HTTP Response, and you use Spring MVC with Controllers you can annotate your controller method as follows:
public #ResponseBody User getUser(){
return userImplClass.findUserByUserName("yourusername");
}
2) If you want the UserImplClass itself to return a JSON String (which I do't recommend, but I leave you the decision), you can use Jackson Object Mapper to do it for you (you can inject it if you declare it as a bean on your configuration xml, or create a new instance of it, I personally prefer injecting it with #Autowired)
public String findUserByUserName(String username) {
User user =iUserDAO.findByUsername(username);
ObjectMapper mapper = new ObjectMapper(); // no need to do this if you inject via #Autowired
return mapper.writeValueAsString(user);
}
The code is listed below:
#Document
#XmlRootElement
public class User {
#Indexed(unique=true)
private String username;
private String firstName;
private String lastName;
private String password;
...... omit setters and getters
}
public interface UserRepo extends MongoRepository<User, String>{
}
public User update(User user) {
User existingUser = userRepo.findByUsername(user.getUsername());
if (existingUser == null) {
return null;
}
existingUser.setFirstName(user.getFirstName());
existingUser.setLastName(user.getLastName());
return userRepo.save(existingUser);
}
when update method invoked, the finds the user based on username and finishes without any exceptions, the returned User obj has all updated value but the underlying mongodb document is not changed! Can anyone help? Thanks.
you need an Id field with #Id annotation