I have a simple spring-boot app where Product needs to be stored and conversion between DTO and Entity needs to happen. I am using the ModelMapper dependency. User can attach a ProductCategory to the Product or leave it empty. Similarly Product can have multiple ReplaceNumber or empty. If I dont attach category it gives error. If I attach category it saves the product with the attached category. If I leave the replaceNumbers array empty it saves. If I fill it it gives errors. Errors are described below.
ProductCategory
#Entity
#Table(name = "product_categories")
public class ProductCategory
{
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#NotBlank
#Column(name = "name", nullable = false)
#Size(max = 20)
private String name;
public ProductCategory()
{
}
public ProductCategory(String name)
{
this.name = name;
}
}
ReplaceNumber
#Entity
#Table(name = "replace_numbers")
public class ReplaceNumber
{
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#NotBlank
#Size(max = 20)
private String partNumber;
#ManyToOne(fetch = FetchType.LAZY, optional = false)
#JoinColumn(name = "product_id", nullable = false)
private Product product;
public ReplaceNumber()
{
}
public ReplaceNumber(String partNumber)
{
this.partNumber = partNumber;
}
}
Product
#Entity
#Table(name = "products", indexes = {#Index(name= "part_number_index", columnList = "part_number", unique = true)})
public class Product
{
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#NotBlank
#Column(name = "part_number", nullable = false)
#Size(max = 20)
private String partNumber;
#NotBlank
#Size(max = 255)
private String description;
#OneToMany(
mappedBy = "product",
cascade = CascadeType.ALL,
fetch = FetchType.EAGER,
orphanRemoval = true
)
#Fetch(FetchMode.SELECT)
private List<ReplaceNumber> replaceNumbers = new ArrayList<>();
#ManyToOne
#JoinColumn(name = "product_category_id", referencedColumnName = "id")
private ProductCategory category;
}
Following are the DTO Classes that need to be converted.
ReplaceNumberRequest
public class ReplaceNumberRequest
{
#NotBlank
#Size(max = 20)
private String partNumber;
public String getPartNumber()
{
return partNumber;
}
public void setPartNumber(String partNumber)
{
this.partNumber = partNumber;
}
}
ProductCategoryResponse
public class ProductCategoryResponse
{
private Long id;
private String name;
public ProductCategoryResponse()
{
}
public ProductCategoryResponse(String name)
{
this.name = name;
}
}
ProductRequest
public class ProductRequest
{
#NotBlank
#Size(max = 20)
private String partNumber;
#NotBlank
#Size(max = 255)
private String description;
private List<ReplaceNumberRequest> replaceNumbers = new ArrayList<>();
private ProductCategoryResponse category;
}
ProductService
#Service
public class ProductService
{
#Autowired
ProductRepository productRepository;
public Product create(ProductRequest productRequest)
{
Product product = new Product();
org.modelmapper.ModelMapper modelMapper = new org.modelmapper.ModelMapper();
modelMapper.map(productRequest, product);
return productRepository.save(product);
}
}
If I post the following JSON from Postman
{
"partNumber": "443455783",
"description": "443434",
"replaceNumbers": [],
"category": ""
}
It goes for saving the empty category and produces the following error.
org.hibernate.TransientPropertyValueException: object references an unsaved transient instance - save the transient instance before flushing : org.walana.GP.model.Product.category -> org.walana.GP.model.ProductCategory; nested exception is java.lang.IllegalStateException: org.hibernate.TransientPropertyValueException: object references an unsaved transient instance - save the transient instance before flushing : org.walana.GP.model.Product.category -> org.walana.GP.model.ProductCategory
If I post the following JSON from Postman
{
"partNumber": "443455783",
"description": "443434",
"replaceNumbers": [
{
"partNumber": "123455"
},
{
"partNumber": "343435"
}
],
"category": {
"id": 1,
"name": "Mounting"
}
}
It gives following error.
could not execute statement; SQL [n/a]; constraint [part_number_index]; nested exception is org.hibernate.exception.ConstraintViolationException: could not execute statement
Related
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);
}
I have something similar to this:
#Entity
#Table(name = "claim", schema = "test")
public class Claim implements Serializable {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "idClaim", unique = true, nullable = false)
private Integer idClaim;
#OneToOne(mappedBy = "claim", cascade = CascadeType.ALL, fetch = FetchType.LAZY)
#JsonManagedReference
private ClaimReturnInfo claimReturnInfo;
#Column(name = "notes")
private String notes;
// Getters and setters
}
#Entity
#Table(name = "claim_returninfo", schema = "test")
public class ClaimReturnInfo implements Serializable {
#Id
#Column(name = "Claim_idClaim")
private Integer id;
#MapsId("Claim_idClaim")
#OneToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "Claim_idClaim")
#JsonBackReference
private Claim claim;
#Column(name = "description")
private String description;
// Getters and setters
}
ClaimReturnInfo Id is not autogenerated because we want to propagate the Id from its parent (Claim). We are not able to do this automatically and we are getting this error: ids for this class must be manually assigned before calling save() when 'cascade' is executed in ClaimReturnInfo .
Is it possible to map Claim Id into ClaimReturnInfo Id or should we do this manually?
Even if we set this ID manually on claimReturnInfo and we can perform updates, we still get this error when trying to create a new Claim:
// POST -> claimRepository.save() -> Error
{
"notes": "Some test notes on a new claim",
"claimReturnInfo": {
"description": "Test description for a new claimReturnInfo"
}
}
In the ServiceImplemetation:
#Override
#Transactional
public Claim save(Claim claim) throws Exception {
if(null != claim.getClaimReturnInfo()) {
claim.getClaimReturnInfo().setId(claim.getIdClaim());
}
Claim claimSaved = claimRepository.save(claim);
return claimSaved;
}
I have tried using the following mappings and from your comments it was apparent that Json object is populated correctly.
I have noticed that the annotation #MapsId is the culprit.If you check the documentation of #MapsId annotation it says
Blockquote
The name of the attribute within the composite key
* to which the relationship attribute corresponds. If not
* supplied, the relationship maps the entity's primary
* key
Blockquote
If you change #MapsId("Claim_idClaim") to #MapsId it will start persisting your entities.
import javax.persistence.*;
#Entity
#Table(name = "CLAIM")
public class Claim {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "idClaim", unique = true, nullable = false)
private Long idClaim;
#Column(name = "notes")
private String notes;
#OneToOne(mappedBy = "claim", cascade = CascadeType.ALL, optional = false)
private ClaimReturnInfo claimReturnInfo;
public Long getIdClaim() {
return idClaim;
}
public String getNotes() {
return notes;
}
public void setNotes(String notes) {
this.notes = notes;
}
public ClaimReturnInfo getClaimReturnInfo() {
return claimReturnInfo;
}
public void setClaimReturnInfo(ClaimReturnInfo claimReturnInfo) {
if (claimReturnInfo == null) {
if (this.claimReturnInfo != null) {
this.claimReturnInfo.setClaim(null);
}
} else {
claimReturnInfo.setClaim(this);
}
this.claimReturnInfo = claimReturnInfo;
}
}
package com.hiber.hiberelations;
import javax.persistence.*;
#Entity
#Table(name = "CLAIM_RETURN_INFO")
public class ClaimReturnInfo {
#Id
#Column(name = "Claim_idClaim")
private Long childId;
#Column(name = "DESCRIPTION")
private String description;
#MapsId
#OneToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "Claim_idClaim")
private Claim claim;
public Long getChildId() {
return childId;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public Claim getClaim() {
return this.claim;
}
public void setClaim(Claim claim) {
this.claim = claim;
}
}
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 faced with the problem, that JSON doesn't containe the list of nested objects.
I have 2 classes, one of them is carrying information about auto service, another one containes information about services.
One autoservice can has many services. So, we have the relation - one to many .
AutoService class:
#Entity
#Table(name = "AutoRate")
public class AutoService {
public AutoService() {
}
#Id
#GeneratedValue(generator = "increment")
#GenericGenerator(name = "increment", strategy = "increment")
private long id;
#Column(name = "serviceName", nullable = false)
private String serviceName;
#Column(name = "imageURL", nullable = false)
private String imageURL;
#Column(name = "mapCoordinate", nullable = false)
private String mapCoordinate;
#Column(name = "websiteURL", nullable = false)
private String websiteURL;
#Column(name = "phoneNumber", nullable = false)
private String phoneNumber;
#OneToMany(fetch = FetchType.EAGER)
#JoinColumn(name = "autoServiceId")
private List<Service> services;
public long getId() {
return id;
}
public String getServiceName() {
return serviceName;
}
public String getImageURL() {
return imageURL;
}
public String getMapCoordinate() {
return mapCoordinate;
}
public String getWebsiteURL() {
return websiteURL;
}
public String getPhoneNumber() {
return phoneNumber;
}
}
Service class:
#Entity
#Table(name = "Service")
public class Service {
public Service() {
}
#Id
#GeneratedValue(generator = "increment")
#GenericGenerator(name = "increment", strategy = "increment")
#Column(name = "serviceId", unique = true, nullable = false)
private long serviceId;
#Column(name = "serviceName", nullable = false)
private String serviceName;
#Column(name = "category", nullable = false)
private String category;
#Column(name = "price", nullable = false)
private int price;
#Column(name = "autoServiceId", nullable = false)
private long autoServiceId;
public long getId() {
return serviceId;
}
public String getCategory() {
return category;
}
public int getPrice() {
return price;
}
public String getServiceName() {
return serviceName;
}
public long getAutoServiceId() {
return autoServiceId;
}
}
Also i am using the JpaRepository to get objects from db:
public interface AutoRateRepository extends JpaRepository<AutoService, Long> {
}
Here is Controller class:
#RestController
#RequestMapping("/directory")
public class ServiceController {
#Autowired
private AutoRateService dataBaseService;
#RequestMapping(value = "/get", method = RequestMethod.GET)
#ResponseBody
public List<AutoService> getData(){
List<AutoService> dataList = dataBaseService.getAll();
return dataList;
}
}
But then when i am trying to get JSON object i am getting next:
[
{
"id": 1,
"serviceName": "SpeedyName",
"imageURL": "Url for speedy",
"mapCoordinate": "123123 44121 ",
"websiteURL": "speedy.com",
"phoneNumber": "1231251"
},
{
"id": 2,
"serviceName": "Другой сервис",
"imageURL": "Урл для второго сервиса",
"mapCoordinate": "123 12фывфы",
"websiteURL": "другойсервис.ком",
"phoneNumber": "12312333"
}
]
There is not lists of nested objects from database ( List<Services>
Can you help me to resolve this problem ?
I was told that i had missed the #JsonManagedReference annotation, but it didn't helped me (
As specified in the comments, you're missing a getServices() method in the AutoService entity exposing the collection for serialization.
As a side note, be weary if your Service entity has a back reference to the parent AutoService. If it does, you'll need to make sure your JSON framework knows how to handle cyclic loops or you will need to trigger ignoring the back reference when you serialize the AutoService instances to avoid a stack overflow.
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.