So I'am trying Spring webFlux and have following code:
#Override
public Flux<? extends AnimalDatabaseEntity> queryAnimals() {
return async(animalsRepository.findAll().stream());
}
private <T> Flux<T> async(Stream<T> stream) {
return Flux.fromStream(stream).publishOn(scheduler);
}
The problem that I get infinite recursion, because "AnimalDatabaseEntity" has field animalFeatures.
#Entity(name = "animals")
public class AnimalDatabaseEntity {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
private Long id;
#Column(name = "name")
private String name;
#Enumerated(EnumType.STRING)
#Column(name = "animal_type")
private AnimalType animalType;
#Column(name = "number_of_legs")
private Integer numberOfLegs;
#Column(name = "is_pet")
private boolean isPet;
#OneToMany(mappedBy = "animalDatabaseEntity", fetch = FetchType.EAGER)
private List<AnimalFeatureEntity> animalFeatures;
}
I don't really get why this does not work???
My best guess is AnimalFeatureEntity contains varaible of type AnimalDatabaseEntity which references back to List<AnimalFeatureEntity> while serializing thus causing an infinite recursion. You can prevent it by adding #JsonIgnore to AnimalDatabaseEntity if it suits your use case. However, if you wish to preserve the bidirectional relationship, then #JsonManagedReference/#JsonBackReference or #JsonIdentityInfo is the way to go.
For example usage, refer this article
Related
I need to fetch names of all students who have enrolled for the courses.
Url:-/students/{course1}/{course2}
Eg /students/java/oracle
How to write controller, service and repository in rest api.
Entity:-
Student
Integer Id,String name and list coursenames
What about?
#Controller
#RequestMapping("/students")
public class StudentController {
#Autowired
private StudentService studentService;
// /students/java,oracle
#GetMapping(value="/{courses}")
#ResponseBody
public String getStudents(#PathVariable String[] courses) {
return studentService.getStudents(courses);
}
}
Student
#Entity
#Table(name = "student")
public class StudentDao {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
private Long id;
#Column(name = "name")
private String name;
#OneToMany(fetch = FetchType.EAGER)
#Fetch(value = FetchMode.SUBSELECT)
#JoinColumn(name = "id", referencedColumnName = "id")
private List<CourseDao> course;
}
Course
#Entity
#Table(name = "course")
public class CourseDao {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
private Long id;
#Column(name = "name")
private String name;
}
In my opinion it is bad rest design. I'll create POST endpoint with body, which contains array with course Id's and find students by course id's.
If the parameters are optional or an array you shouldn't use a path variable but use a request parameter.
I'm coding a CRUD JPA web application. My goal is that a given parent Vehicle can only have a single child Driver, but during runtime this same Driver can instead be assigned to another Vehicle and vice versa. To my understanding, this could be accomplished via an OneToOne relationship.
I've tried some different approaches, but to no success. I can assign a Vehicle to a Driver just fine, but when I try to update/create a new Vehicle and give him a Driver, via controllers, nothing happens. I can only do it the other way around. I'm assuming this is because Vehicle is the parent and I can only create a new relation by updating a parent.
My question is, is it possible to make these updates bidirectional and how can I achieve that?
I've tried using a shared primary key, using a foreign key, using a join table. The result is always the same and I can't quite grasp why. I have an OneToMany relationship working on this application and it works as I expect it to work. I can update on one side or the other, delete on one side or the other. Both entities have been updated. OneToOne? Parent seems to have all the power.
This is what I'm working with right now:
Driver
#Entity
#Table(name= "drivers")
public class Driver {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;
#Column(nullable = false)
private String name;
#Column(nullable = false)
private int age;
#OneToOne(mappedBy = "driver")
private Vehicle vehicle;
Vehicle
#Entity
#Table(name= "vehicles")
public class Vehicle {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;
#Column(nullable = false)
private String make;
#Column(nullable = false)
private String model;
#Column(nullable = false)
private int mileage;
#Column(nullable = false)
private int year;
#Column(nullable = false)
private int fuel;
#OneToOne
#JoinColumn(name = "driver_id")
private Driver driver;
And just for reference, this is the OneToMany relationship I have and that I'm happy with. I'd like my OneToOne to have the same behavior, except I don't need to save a list of entities, only one.
#Entity
#Table(name="stops")
public class Stop {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;
#Column(nullable = false)
private String name;
#ManyToOne
#JoinColumn(name="route_id")
private Route route;
#Entity
#Table(name="routes")
public class Route {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;
#Column(nullable = false)
private String name;
#OneToMany
#JoinColumn(name = "route_id")
private List<Stop> stops = new ArrayList<>();
Any tips would be appreciated, thank you for your time.
I have two entities in one to many relationship in my spring-data-jpa project.
Parent entity -
#Entity
#Table(name = "code_group")
public class CodeGroup implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.SEQUENCE)
private Long id;
#NaturalId
#Column(nullable = false)
private String entityId;
#OneToMany
#JoinColumn(name = "codeGroupId", referencedColumnName = "entityId")
private List<SystemCode> systemCodes;
// .. getters setters
}
Child entity -
#Entity
#Table(name = "system_code")
public class SystemCode implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.SEQUENCE)
private Long id;
#Column(nullable = false)
private String codeGroupId;
#Column(nullable = false)
#Enumerated(EnumType.STRING)
private ActiveOrInactive status;
// getters and setters
}
status column is of enum type, it can only have Active or Inactive value.
My existing code works fine. It is fetching code group with associated system codes. I want to filter system code with status='Active'. How to do this?
Try like this:
#OneToMany
#JoinColumn(name = "codeGroupId", referencedColumnName = "entityId")
#Where(clause = "status= 'Active'")
private List<SystemCode> systemCodes;
You can create such methods in your repo:
List<CodeGroup> getAllBySystemCodes_Status(ActiveOrInactive status);
default List<CodeGroup> getAllActive() {
return getAllBySystemCodes_Status(ActiveOrInactive.Active);
}
default List<CodeGroup> getAllInactive() {
return getAllBySystemCodes_Status(ActiveOrInactive.Inactive);
}
i'm trying to solve infinity recursion issue with no success !
project: spring boot and postgresql
i have 3 entities : course, course outline and course schedule :
public class Course implements Serializable {
private static final long serialVersionUID = -6645577819394287204L;
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private UUID id;
#OneToMany(mappedBy = "course", cascade = CascadeType.REMOVE)
#OrderBy("rank ASC")
private List<CourseOutline> outlines;
....
}
public class CourseOutline implements Serializable {
private static final long serialVersionUID = -6645577819394287204L;
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private UUID id;
#ManyToOne
#JoinColumn(name = "course", nullable = false)
#JsonIgnore
private Course course;
private Integer rank;
#OneToMany(mappedBy = "outline", cascade = CascadeType.REMOVE)
#OrderBy("day DESC, started ASC")
private Set<CourseSchedule> schedules;
...
}
public class CourseSchedule implements Serializable {
private static final long serialVersionUID = -6645577819394287204L;
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private UUID id;
#ManyToOne
#JoinColumn(name = "instructor", nullable = true)
#JsonManagedReference
private Person instructor;
#ManyToOne
#JoinColumn(name = "outline", nullable = false)
#JsonIgnore
private CourseOutline outline;
...
}
in REST API i make a call to retrieve a List of CourseOutline by course
using CourseOutline Repository :
List<CourseOutline> findAllByCourse(Course course);
but i get below error :
Could not write JSON: Infinite recursion (StackOverflowError); nested
exception is com.fasterxml.jackson.databind.JsonMappingException:
Infinite recursion (StackOverflowError) (through reference chain:
java.util.ArrayList[2]-myDomain.api.models.entities.CourseOutline[\"schedules\"])"
I have several similar tables in DB.
Now I use for each table own Model and Repository
But I think, this is not right decision.
Can I make a one Model and Repository for all similar tables?
#Entity
#Table(name = "BEDROOM", schema = "public")
public class BedroomModel extends AllFinishProductModel{
#Column(name = "PHOTO")
private String photo;
#Id
#Column(name = "ID")
#GeneratedValue(strategy=GenerationType.IDENTITY)
private Long id;
#Column
private String name;
#Column(name = "DESCRIPTION")
private String description;
#Column(name = "STRUCTURE") //organza, curtain ....
private String structure;
#Column(name = "PAINT") //abstraction, geometric ....
private String paint;
#Column(name = "HEIGHT")
private String height;
#Column(name = "COLOR")
private String color;
#Column(name = "QUANTITY")
private Double quantity;
#Column(name = "PRICE")
private BigDecimal price;
#Column(name = "SEWED")
private String itIsSewed;
... getters and setters
}
I have a similar tables: CABINET, GUESTROOM, CHILDREN_ROOM, KITCHEN, CURTAIN and TULLE.
Which code should be used for repository?
I tried to find answers to the questions inhttps://docs.spring.io/spring-data/data-commons/docs/1.6.1.RELEASE/reference/html/repositories.html
But I don't find answers here.
Can you give advice, how to make it or link?
You can use entity inheritance with #MappedSuperclass annotation on parent class to get common properties in child classes/tables.
So, for example you have a parent Room entity with common properties, which you annotate with #MappedSuperclass.
#MappedSuperclass
public class Room {
#Column
private String name;
#Column(name = "DESCRIPTION")
private String description;
// some more common properties
}
And concrete rooms, e.g.:
#Entity
public class Bedroom extends Room
{
// common properties will be inherited
private Bed bed;
private NightLamp nightLamp;
}
Now, the important part is that Room is not mapped as any table. The room is a "virtual" table, which doesn't exist in the db. Only concrete entities exist as tables, like Bedroom.
Here you have the link to the official javadoc:
http://docs.oracle.com/javaee/5/api/javax/persistence/MappedSuperclass.html