Im learning, and so far i created many to many bidirectional database - user can create many groups and group can have many users - and i cannot find a way for my GroupsController Post mapping to work, from my understanding, it requires to get firstly Users id, in order to set the right relationship in Join table for Group, because the relationship should be set only when user create/join group, not when user create sign up procedure. Postman throws 500 and intelliJ:
Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is java.lang.NullPointerException: Cannot invoke "java.lang.Long.longValue()" because the return value of "com.ilze.highlight.entity.Groups.getId()" is null] with root cause
java.lang.NullPointerException: Cannot invoke "java.lang.Long.longValue()" because the return value of "com.ilze.highlight.entity.Groups.getId()" is null
I use lombok - #Data, #Getter, therefore getId() should be available for use from Group class. My GroupsController with POST mapping when user decides to create a new group:
#RestController
#RequestMapping("api/groups") // pre-path
public class GroupsController{
#Autowired
private GroupsService groupsService;
#Autowired
private UserService userService;
#Autowired
private final GroupsRepository groupsRepository;
#Autowired
private UserRepository userRepository;
public GroupsController(GroupsRepository groupsRepository) {
this.groupsRepository = groupsRepository;
}
#GetMapping("/all-groups")
public List<Groups> getGroups(){
return (List<Groups>) groupsRepository.findAll();
}
#PostMapping("/user/{usersId}/create-group")
public ResponseEntity<Groups> createGroup(#PathVariable(value = "usersId") Long usersId, #RequestBody Groups groupRequest){
Groups group = userRepository.findById(usersId).map(users -> {
long groupsId = groupRequest.getId();
// add and create new group
users.addGroup(groupRequest);
return groupsRepository.save(groupRequest);
}).orElseThrow(() -> new ResourceNotFoundException("Not found user with id = " + usersId));
return new ResponseEntity<>(group, HttpStatus.CREATED);
}
}
Group database class:
#Data
#Entity
#AllArgsConstructor
#NoArgsConstructor
#Getter
#Table(name = "group_collection")
public class Groups {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
private Long id;
#Column(name ="group_name", unique = true, nullable = false, length = 20)
private String groupName;
#Column(name = "size", nullable = false)
private int size;
#Column(name = "strict", nullable = false)
private boolean strict;
#Column(name = "open", nullable = false)
private boolean open;
#Column(name ="description", length = 300)
private String description;
#Column(name = "create_time", nullable = false)
private LocalDateTime createTime;
#ManyToMany(fetch = FetchType.LAZY,
cascade = {
CascadeType.PERSIST,
CascadeType.MERGE,
CascadeType.DETACH,
CascadeType.REFRESH
},
mappedBy = "groups")
#JsonIgnore
private Set<User> users = new HashSet<>();
public Set<User> getUsers() {
return users;
}
public void setUsers(Set<User> users) {
this.users = users;
}
}
And Users class for database:
#Data
#Entity
#AllArgsConstructor
#NoArgsConstructor
#Table(name = "users")
public class User {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
private Long id;
#Column(name = "username", unique = true, nullable = false, length = 100)
private String username;
#Column(name = "password", nullable = false)
private String password;
#Column(name = "email", nullable = false)
private String email;
#Column(name = "create_time", nullable = false)
private LocalDateTime createTime;
#Enumerated(EnumType.STRING)
#Column(name = "role", nullable = false)
private Role role;
#Transient
private String accessToken;
#Transient
private String refreshToken;
#ManyToMany(fetch = FetchType.LAZY,
cascade = {
CascadeType.PERSIST,
CascadeType.MERGE,
CascadeType.DETACH,
CascadeType.REFRESH
})
#JoinTable(name = "groups_x_user",
joinColumns = { #JoinColumn(name = "users_id") },
inverseJoinColumns = {#JoinColumn(name = "groups_id")})
private Set<Groups> groups = new HashSet<>();
public void addGroup(Groups group) {
this.groups.add(group);
group.getUsers().add(this);
}
public void removeGroup(long id){
Groups group = this.groups.stream().filter(g ->
g.getId() == id).findFirst().orElse(null);
if(group != null){
this.groups.remove(group);
group.getUsers().remove(this);
}
}
For reference my GroupsService implementation:
#Service
public class GroupsServiceImpl implements GroupsService{
private final GroupsRepository groupsRepository;
public GroupsServiceImpl(GroupsRepository groupsRepository) {
this.groupsRepository = groupsRepository;
}
#Override
public Groups saveGroup(Groups group) {
group.setCreateTime(LocalDateTime.now());
return groupsRepository.save(group);
}
#Override
public Optional<Groups> findByGroupName(String groupName) {
return groupsRepository.findByGroupName(groupName);
}
}
You need to persist the object from request. And since you have Many-2-Many relation, you can insert related object from both sides. In your case: just add existing user to the newly created group
The method will look something like that:
#PostMapping("/user/{usersId}/groups")
public ResponseEntity<Groups> createGroup(#PathVariable(value = "usersId") Long usersId, #RequestBody Groups groupRequest) {
Groups createdGroup = userRepository.findById(usersId)
.map(user -> {
groupRequest.setId(null); // ID for new entry will be generated by entity framework, prevent override from outside
groupRequest.getUsers().add(user); // add relation
return groupsRepository.save(groupRequest);
}).orElseThrow(() -> new ResourceNotFoundException("Not found user with id = " + usersId));
return new ResponseEntity<>(createdGroup, HttpStatus.CREATED);
}
Related
Problem
I am trying to store an object in my Postgres database. This consists of the Order.class, (List) OrderDevice.class, and a Department.class.
The important thing is that the OrderDevices are always stored new in the DB, but a Department may already exist.
When I try to save the object to my database using save I get the following error message: (shown below)
I get the error message "detached entity passed to persist: com.niclas.model.OrderDevice" if the department does not exist yet, if the department exists the error message looks like this: "detached entity passed to persist: com.niclas.model.Department".
Solution attempts
This solution cannot be used because I do not use bidirectional mapping.
(I don't want to use a bidirectional mapping because I want to access the departments without an order.)
I also tried to change the Cascade types to MERGE like in this solution
I also tried using #Transactional on the method
I also tried to save the children in the database first and then the parent like this:
departmentRepository.save(order.getDepartment()); orderDeviceRepository.saveAll(order.getDevices()); orderRepository.save(order);
I hope I have described my good enough and I am happy about suggestions for solutions
Error.log
The log can be viewed here. (The formatting did not work here)
Order.class
#Entity
#Table(name = "orders")
public class Order extends AuditModel {
#Id
#Column(name = "id")
#GeneratedValue(strategy = GenerationType.AUTO) //TODO better config for GenerationType
private long id;
#Column(name = "order_id")
private String orderId;
#Column(name = "department_id")
private long departmentId;
#OneToOne(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
#JoinColumn(name = "department", referencedColumnName = "id")
private Department department;
#JsonProperty("deviceList")
#OneToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
#JoinColumn(name = "order_id", referencedColumnName = "order_id")
private List<OrderDevice> devices;
#JsonProperty("forename")
#Column(name = "sender_forename")
private String senderForename;
#JsonProperty("surname")
#Column(name = "sender_surname")
private String senderSurname;
#Column(name = "notes", columnDefinition = "TEXT")
private String notes;
#Column(name = "month")
private int month;
#Column(name = "year")
private int year;
public Order() {
}
... Getter/Setters
}
OrderDevice.class
#Entity
#Table(name = "order_devices")
public class OrderDevice extends AuditModel{
#Id
#Column(name = "id")
#GeneratedValue(strategy = GenerationType.AUTO) //TODO better config for GenerationType
private long id;
#Column( name = "order_id", insertable = false, updatable = false )
private String orderId;
#Column(name = "device_id")
private long deviceId;
#Column(name = "device_name")
private String deviceName;
#Column(name = "priceName")
private String priceName;
#Column(name = "price")
private double price;
#Column(name = "count")
private int count;
public OrderDevice() {
}
... Getters/Setters
}
Department.class
#Entity
#Table(name = "departments")
public class Department {
//TODO add Form Validation
//TODO better Naming for From Attributes on Frontend and Backend
#Id
#Column(name = "id")
#GeneratedValue(strategy = GenerationType.AUTO) //TODO better config for GenerationType
private long id;
#Column(name = "department_name")
private String department;
#Column(name = "contact_person_forename")
private String forename;
#Column(name = "contact_person_surname")
private String surname;
#Column(name = "contact_person_mail")
private String mail;
#Column(name = "street")
private String street;
#Column(name = "house_number")
private String houseNumber;
#Column(name = "location")
private String location;
#Column(name = "postal_code")
private int postalCode;
#Column(name = "country")
private String country;
#Column(name = "auto_send_invoice")
private boolean autoSend;
#Column(name = "registered")
private boolean registered;
public Department() {
}
... Getter/Setters
}
OrderController.class
#Slf4j
#RestController
public class OrderController {
private final DepartmentRepository departmentRepository;
private final OrderRepository orderRepository;
private final OrderDeviceRepository orderDeviceRepository;
public OrderController(OrderRepository orderRepository, DepartmentRepository departmentRepository,
OrderDeviceRepository orderDeviceRepository) {
this.orderRepository = orderRepository;
this.departmentRepository = departmentRepository;
this.orderDeviceRepository = orderDeviceRepository;
}
#PostMapping("/orders/add")
public ResponseEntity<Order> addDepartment(#RequestBody Order order) throws JsonProcessingException {
order.setOrderId(order.generateOrderId());
DateTime dateTime = new DateTime();
order.setMonth(dateTime.getMonthOfYear());
order.setYear(dateTime.getYear());
order.getDevices().forEach(orderDevice -> {
orderDevice.setOrderId(order.getOrderId());
});
//departmentRepository.save(order.getDepartment());
//orderDeviceRepository.saveAll(order.getDevices());
orderRepository.save(order);
return new ResponseEntity<>(order, HttpStatus.CREATED);
}
Update
If the objects are created in this way, no error will occur and the order will be successfully saved in the database.
However, I don't understand why it works this way and not via ObjectMapper. Does anyone know why?
#PostMapping("/orders/add")
public ResponseEntity<Order> addDepartment(#RequestBody JsonNode jsonNode) throws JsonProcessingException {
Order order = new Order();
JsonNode departmentJson = jsonNode.get("department");
Department department;
if ( departmentJson.get("id").canConvertToInt() ) {
department = departmentRepository.findDepartmentById(departmentJson.get("id").asInt());
} else {
department = new Department();
department.setDepartment(departmentJson.get("department").asText());
department.setForename(departmentJson.get("forename").asText());
department.setSurname(departmentJson.get("surname").asText());
department.setMail(departmentJson.get("mail").asText());
department.setStreet(departmentJson.get("street").asText());
department.setHouseNumber(departmentJson.get("houseNumber").asText());
department.setLocation(departmentJson.get("location").asText());
department.setPostalCode(departmentJson.get("postalCode").asInt());
department.setCountry(departmentJson.get("country").asText());
department.setAutoSend(departmentJson.get("autoSend").asBoolean());
department.setRegistered(departmentJson.get("registered").asBoolean());
}
order.setDepartment(department);
order.setOrderId(order.generateOrderId());
order.setDepartmentId(department.getId());
List<OrderDevice> orderDevices = new ArrayList<>();
JsonNode devices = jsonNode.get("deviceList");
for (JsonNode node : devices) {
//TODO replace this mess with objectMapper
if (node.has("count") && node.get("count").asInt() != 0){
OrderDevice device = new OrderDevice();
device.setOrderId(order.getOrderId());
device.setDeviceId(node.get("id").asLong());
device.setDeviceName(node.get("deviceName").asText());
device.setPriceName(node.get("priceName").asText());
device.setPrice(node.get("price").asDouble());
device.setCount(node.get("count").asInt());
orderDevices.add(device);
}
}
order.setDevices(orderDevices);
order.setSenderForename(jsonNode.get("forename").asText());
order.setSenderSurname(jsonNode.get("surname").asText());
order.setNotes(jsonNode.get("notes").asText());
DateTime dateTime = new DateTime();
order.setMonth(dateTime.getMonthOfYear());
order.setYear(dateTime.getYear());
orderRepository.save(order);
return new ResponseEntity<>(order, HttpStatus.CREATED);
}
You can try to use instead of orderRepository.save(order) use orderRespostiory.saveOrUpdate(order).
I have a spring service class where I'm loading a JPA object (target) via CRUD. This target class has a one-to-may mapping that is set to lazy loading.
I would like to query this object inside a spring service method that is annotated with #Transactional and avoid that the childs are being loaded.
When I execute the following code all child data is loaded and laziness is ignored.
#Override
#Transactional
public boolean changeState(boolean enabled, final EventType eventType, final String deviceSerialNumber) {
final UniqueUser user = userService.getUser();
final Target target = targetRepository.findEventsByUserIdAndTenantIdAndTargetDeviceId(user.getUserId(), user.getTenantId(), deviceSerialNumber);
//here everything gets loaded
if (target == null) {
return false;
}
final List<EventHistory> events = target.getEvents().stream()
.filter(event -> event.getEventType() == eventType)
.filter(event -> event.isActive() != enabled)
.collect(Collectors.toList());
events.forEach(event -> event.setActive(enabled));
if (events.isEmpty()) {
return false;
}
return true;
}
Mappings:
#ToString
#Entity
#Table(name = "target")
public class Target {
#Id
#GeneratedValue(generator = "uuid")
#GenericGenerator(name = "uuid", strategy = "org.hibernate.id.UUIDGenerator")
#Column(name = "id", unique = true)
private UUID id;
#Column(name = "user_id")
private String userId;
#Column(name = "tenant_id")
private String tenantId;
#Column(name = "target_device_id")
private String targetDeviceId;
#Column(name = "target_type")
private TargetType targetType;
#OneToMany(mappedBy = "target", cascade = CascadeType.ALL, orphanRemoval = true, fetch = FetchType.LAZY)
#JsonManagedReference
private List<EventHistory> events = new ArrayList<>();
public void addEvents(EventHistory event) {
events.add(event);
event.setTarget(this);
}
}
#Entity
#Data
#Table(name = "event_history")
public class EventHistory {
#Id
#GeneratedValue(generator = "uuid")
#GenericGenerator(name = "uuid", strategy = "org.hibernate.id.UUIDGenerator")
#Column(name = "id", unique = true)
private UUID id;
#Column(name = "active")
private boolean active;
#OneToMany(mappedBy = "event", cascade = CascadeType.ALL, orphanRemoval = true)
#JsonManagedReference
private List<EventTimestamp> timestamps = new ArrayList<>();
#ManyToOne(optional = false, cascade = CascadeType.ALL, fetch = FetchType.LAZY)
#JoinColumn(name = "target_id", nullable = false)
#OnDelete(action = OnDeleteAction.CASCADE)
#JsonBackReference
private Target target;
public void addTimestamps(EventTimestamp eventTimestamp) {
timestamps.add(eventTimestamp);
eventTimestamp.setEvent(this);
}
}
#Entity
#Data
#Table(name = "event_timestamp")
public class EventTimestamp {
#Id
#GeneratedValue(generator = "uuid")
#GenericGenerator(name = "uuid", strategy = "org.hibernate.id.UUIDGenerator")
#Column(name = "id", unique = true)
private UUID id;
#Column(name = "due_timestamp")
private Timestamp dueTimestamp;
#Column(name = "period")
private String period;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "event_id", nullable = false)
#JsonBackReference
private EventHistory event;
So my question is how to keep lazy loading inside transaction annotated functions?
My first assumption that the root cause had been the wrongly implemented repository function was wrong. The real issue was the #ToString annotation. This added the one-to-many event collection to toString(). While being inside the transaction and accessing the object, toString got invoked and the the collection was loaded.
Solution was to exclude the collection from toString via.
#OneToMany(mappedBy = "target", cascade = CascadeType.ALL, orphanRemoval = true)
#ToString.Exclude
private List<EventHistory> events;
I figured it out. The problem was ins the Repository code. The findBy method is expecting a List instead of a single object.
My original repository looked like this
#Repository
public interface TargetRepository extends CrudRepository<Target, UUID> {
Target findEventsByUserIdAndTenantIdAndTargetDeviceId(String userId, String tenantId, String targetId);
}
Changing it to the below version fixed it.
#Repository
public interface TargetRepository extends CrudRepository<Target, UUID> {
List<Target> findEventsByUserIdAndTenantIdAndTargetDeviceId(String userId, String tenantId, String targetId);
}
The problem is that by adding a "message" object type to the "StoreActivity" entity, the first time, it does so without any problem, when iterating a second time, the program throws the exception:Multiple representations of the same entity
I have tried in the parent entity with all types of "cascades" and it does not work
Entity StoreActivity :
#Entity
#Table(name="store_activities")
public class StoreActivity implements Serializable {
#EmbeddedId
StoreActivityPk storeActivityPk = new StoreActivityPk();
#ManyToOne
#JoinColumn(name = "store_id", insertable = false, updatable = false)
#MapsId("storeId")
private Store store;
#ManyToOne
#JoinColumn(name = "activity_id", insertable = false, updatable = false)
#MapsId("activityId")
private Activity activity;
#NotEmpty
#Column(length = 500, nullable=true)
private String comment;
#OneToMany(fetch = FetchType.LAZY, cascade = {CascadeType.ALL,CascadeType.DETACH,CascadeType.PERSIST,CascadeType.REFRESH,CascadeType.REMOVE})
#JoinColumns({
#JoinColumn(name="date_activity", referencedColumnName="dateActivity"),
#JoinColumn(name="store_id", referencedColumnName="store_id"),
#JoinColumn(name="activity_id", referencedColumnName="activity_id"),
#JoinColumn(name="store_activity_hour", referencedColumnName="storeActivityHour")
})
private List<Message> messages;
//Getters and setters ...
}
StoreActivityPk :
#Embeddable
public class StoreActivityPk implements Serializable{
private Long activityId;
private Long storeId;
#Temporal(TemporalType.DATE)
private Date dateActivity;
#Temporal(TemporalType.TIME)
private Date storeActivityHour;
}
Message entity :
#Entity
#Table(name = "messages")
public class Message implements Serializable {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long messageId;
#NotEmpty
#Column(length = 1000, nullable=false)
private String messageContent;
#Column(length = 1, nullable=false)
private Boolean messageRead;
#OneToOne(cascade = CascadeType.ALL)
#JoinColumn(name="user_id")
private UserCheck userCheckSender;
#Temporal(TemporalType.TIMESTAMP)
private Date dateMessage;
//Getters and setters
}
Controller :
public class StoreActivityController {
#PostMapping("/save")
public String save(#Valid Message message, BindingResult result, Model model, RedirectAttributes flash,
SessionStatus sessionStatus, Authentication authentication,
#RequestParam(name = "storeId", required = true) Long storeId,
#RequestParam(name = "activityId", required = true) Long activityId,
#RequestParam(name = "dateActivity", required = true) #DateTimeFormat(pattern="yyyy-MM-dd") Date dateActivity) {
if (result.hasErrors()) {
model.addAttribute("title", "Mensajes");
model.addAttribute("subtitle", "Mensajes de la actividad diaria");
return "frontend/message/activitymessage";
}
UserCheck userCheck = (UserCheck) authentication.getPrincipal();
message.setUserCheckSender(userCheck);
StoreActivity storeActivity = storeActivityService.findById(activityId, storeId, new Date());
storeActivity.addMessage(message);
storeActivityService.saveStoreActivity(storeActivity);
sessionStatus.isComplete();
flash.addFlashAttribute("success", "Mensaje Enviado");
return "redirect:/message/activity/" + storeActivity.getStoreActivityPk().getActivityId() + "/store/"
+ storeActivity.getStoreActivityPk().getStoreId();
}
}
Actual result console :
2019-08-08 17:44:54.918 WARN 5024 --- [io-8090-exec-10] .m.m.a.ExceptionHandlerExceptionResolver : Resolved [org.springframework.dao.InvalidDataAccessApiUsageException: Multiple representations of the same entity [cl.tricotcorp.app.checklist.models.entity.UserCheck#1] are being merged. Detached: [cl.tricotcorp.app.checklist.models.entity.UserCheck#8f06f5d]; Managed: [cl.tricotcorp.app.checklist.models.entity.UserCheck#46781997]; nested exception is java.lang.IllegalStateException: Multiple representations of the same entity [cl.tricotcorp.app.checklist.models.entity.UserCheck#1] are being merged. Detached: [cl.tricotcorp.app.checklist.models.entity.UserCheck#8f06f5d]; Managed: [cl.tricotcorp.app.checklist.models.entity.UserCheck#46781997]]
I have a following error:
com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Cannot delete or update a parent row: a foreign key constraint fails (`spindledb`.`section`, CONSTRAINT `FK_ftoru9cp83n512p9is8x3vo53` FOREIGN KEY (`scenario_id`) REFERENCES `scenario` (`scenario_id`))
Here are my classes:
Scenario:
#Entity
#Table(name = "scenario")
public class Scenario {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "scenario_id")
private int id;
#Column(name = "title", nullable = false)
private String title;
#NotNull
#DateTimeFormat(pattern = "dd/MM/yyyy")
#Column(name = "creation_date", nullable = false)
#Type(type = "org.jadira.usertype.dateandtime.joda.PersistentLocalDate")
private LocalDate creationDate;
#ManyToOne
#LazyCollection(LazyCollectionOption.FALSE)
#JoinColumn(name = "id", nullable = false)
private User user;
#OneToMany(mappedBy = "scenario", orphanRemoval = true)
#LazyCollection(LazyCollectionOption.FALSE)
private Set<Plot> plotList = new HashSet<Plot>();
#OneToMany(mappedBy = "scenario", orphanRemoval = true)
#LazyCollection(LazyCollectionOption.FALSE)
private Set<Character> characterList = new HashSet<Character>();
#OneToMany(mappedBy = "scenario", cascade=CascadeType.ALL, orphanRemoval = true)
#LazyCollection(LazyCollectionOption.FALSE)
#OrderBy("sequence ASC")
private Set<Section> sectionList = new HashSet<Section>();
Section:
#Entity
#Table(name = "section")
public class Section {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "section_id")
private int id;
#Size(min = 4, max = 50)
#NotNull
#Column(name = "name")
private String name;
#NotNull
#Column(name = "type")
private String type = SectionType.TEXT.getSectionType();
#Column(name = "visibility")
private boolean visibility;
#NotNull
#Column(name = "sequence")
private int sequence;
#ManyToOne (cascade=CascadeType.ALL)
#LazyCollection(LazyCollectionOption.FALSE)
#JoinColumn(name = "scenario_id", nullable = false)
private Scenario scenario;
Controller:
#RequestMapping(value = { "/delete-{id}-scenario" }, method = RequestMethod.GET)
public String deleteScenario(#PathVariable int id) {
scenarioService.deleteScenarioById(id);
return "redirect:/home";
}
Scenario service:
#Service("scenarioService")
#Transactional
public class ScenarioServiceImpl implements ScenarioService {
#Autowired
private ScenarioDao dao;
#Override
public Scenario findById(int id) {
return dao.findById(id);
}
#Override
public void saveScenario(Scenario scenario) {
dao.saveScenario(scenario);
}
public void updateScenario(Scenario scenario) {
Scenario entity = dao.findById(scenario.getId());
if(entity!=null){
entity.setTitle(scenario.getTitle());
entity.setCreationDate(scenario.getCreationDate());
}
}
#Override
public void deleteScenarioById(int id) {
dao.deleteScenarioById(id);
}
Dao
#Repository("scenarioDao")
public class ScenarioDaoImpl extends AbstractDao<Integer, Scenario> implements ScenarioDao {
#Override
public Scenario findById(int id) {
return getByKey(id);
}
#Override
public void saveScenario(Scenario scenario) {
persist(scenario);
}
#Override
public void deleteScenarioById(int id) {
Query query = getSession().createSQLQuery("delete from scenario where id = :id");
query.setString("id", ""+id);
query.executeUpdate();
}
I understand that the problem is that there may be a Section that can not exist without scenario. Right now however section table in database is empty and I still can't remove Scenario. Thanks for advice
Deleting an entity via Query would bypass any Cascade settings you put via annotation.
I would suggest find the entity first by id, then delete the entity object:
Object scenario = session.load(Scenario.class, id);
if (scenario != null) {
session.delete(scenario);
}
use cascade=CascadeType.ALL with all #ManyToOne relations in class Scenario because if you are going to delete any Scenario from database it must not be referenced any where in data base.
the other way to delete is.
Serializable id = new Long(1); //your id
Object persistentInstance = session.load(Scenario.class, id);
if (persistentInstance != null) {
session.delete(persistentInstance);
}
I write my first java application to read rss stream and use spring, spring-data, hibernate.
My models.
RssFeed:
#Entity(name = "RssFeed")
#Table(name = "FEED")
#JsonIgnoreProperties({"rssChannel"})
public class RssFeed {
#Id
#GeneratedValue
#Column
private Integer id;
#Column(unique = true)
#Index(name = "title_index")
private String title;
#Column
#URL
private String link;
#Column
private String description;
#Column
private String content;
#Column
#Temporal(TemporalType.TIMESTAMP)
private Date pubDate;
#Column
#Temporal(TemporalType.TIMESTAMP)
private Date updateDate;
#ManyToOne
#JoinColumn(name = "channelId")
private RssChannel rssChannel;
#ManyToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
#JoinTable(name = "feed_category",
joinColumns = {#JoinColumn(name = "feed_id", nullable = false, updatable = false)},
inverseJoinColumns = {#JoinColumn(name = "category_id", nullable = false, updatable = false)})
private Set<RssCategory> rssCategories = new LinkedHashSet<RssCategory>();
}
RssChannel:
#Entity(name = "RssChannel")
#Table(name = "Channel",
uniqueConstraints = #UniqueConstraint(columnNames = {"link"}))
#JsonIgnoreProperties({"feeds"})
public class RssChannel implements Serializable{
#Id
#GeneratedValue
#Column
private Integer id;
#Column
private String title;
#Column(unique = true)
#org.hibernate.validator.constraints.URL
private String link;
#Column
#org.hibernate.validator.constraints.URL
private String image;
#Column
private String description;
#OneToMany(mappedBy = "rssChannel", cascade = CascadeType.ALL, orphanRemoval = true)
private List<RssFeed> feeds = new LinkedList<RssFeed>();
}
And RssCategory:
#Entity(name = "RssCategory")
#Table(name = "CATEGORY")
#JsonIgnoreProperties({"rssFeeds"})
public class RssCategory {
#Id
#GeneratedValue
#Column
private Integer id;
#Column(unique = true)
private String title;
#ManyToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER, mappedBy = "rssCategories")
public Set<RssFeed> rssFeeds = new LinkedHashSet<RssFeed>();
}
I use CrudRepository for manipulation with data. When save RssFeed without many to many it`s ok:
RssChannel channel = rssChannelService.get(url.toString());
rssFeed.setRssChannel(channel);
rssFeedService.save(rssFeed);
But when i add RssCategory:
rssCategory rssCategory = rssCategoryService.findOrCreate("test");
rssFeed.getRssCategories().add(rssCategory);
rssFeedService.save(rssFeed);
get exception: rg.hibernate.PersistentObjectException: detached entity passed to persist: RssCategory.
My RssFeedServiceImpl:
#Service
public class RssFeedServiceImpl implements RssFeedService {
#Autowired
private RssChannelDAO rssChannelDAO;
#Autowired
private RssFeedDAO rssFeedDAO;
#Override
public Page<RssFeed> findAll(Pageable pageable) {
return rssFeedDAO.findAll(pageable);
}
#Override
public Page<RssFeed> findAll(int rssChannelId, Pageable pageable) {
RssChannel rssChannel = rssChannelDAO.findOne(rssChannelId);
return rssFeedDAO.findByRssChannel(rssChannel, pageable);
}
#Override
public RssFeed get(String title) {
return rssFeedDAO.findByTitle(title);
}
#Override
public RssFeed save(RssFeed rssFeed) {
return rssFeedDAO.save(rssFeed);
}
}
And RssCategoryServiceImpl:
#Service
public class RssCategoryServiceImpl implements RssCategoryService {
#Autowired
RssCategoryDAO rssCategoryDAO;
#Override
public RssCategory findOrCreate(String title) {
RssCategory category = rssCategoryDAO.findByTitle(title);
if (category == null) {
category = new RssCategory();
category.setTitle(title);
category = rssCategoryDAO.save(category);
}
return category;
}
}
How save many to many?
You probably need to save your RssCategory first, in order to have an ID to store in feed_category table. This last save will be automatically made when you make the assignment:
rssFeed.getRssCategories().add(rssCategory);
but first you need to do:
rssFeedService.save(rssCategory);
Probably you'll need to put this operations within a transaction.