We Keep Coding

Get data from Junction Table with Android Room

I am currently building an android app, which displays a Route, which is constructed out of multiple waypoints. I already planned the database schema (chen-notation [possibly invalid "syntax"]):
I tried to recreate the n-m relation with android room, but I can't figure out how I can retrieve the index_of_route attribute of the junction table (route_waypoint).
I want the junction table attribute index_of_route, when I get the Data like so:
#Transaction
#Query("SELECT * FROM POIRoute")
List<RouteWithWaypoints> getRoutes();
inside the POIWaypoint class (maybe as extra attribute), or at least accessible from another class which maybe is implemented like so:
#Embedded
POIWaypoint waypoint;
int indexOfRoute;
Currently I don't get the indexOfRoute attribute from the junction table.
My already created classes:
RouteWithWaypoints:
public class RouteWithWaypoints {
#Embedded
private POIRoute poiRoute;
#Relation(parentColumn = "id",entityColumn = "id",associateBy = #Junction(value = RouteWaypoint.class, parentColumn = "routeId", entityColumn = "waypointId"))
private List<POIWaypoint> waypoints;
public POIRoute getPoiRoute() {
return poiRoute;
}
public void setPoiRoute(POIRoute poiRoute) {
this.poiRoute = poiRoute;
}
public List<POIWaypoint> getWaypoints() {
return waypoints;
}
public void setWaypoints(List<POIWaypoint> waypoints) {
this.waypoints = waypoints;
}
RouteWaypoint:
#Entity(primaryKeys = {"waypointId", "routeId"}, foreignKeys = {
#ForeignKey(entity = POIWaypoint.class, parentColumns = {"id"}, childColumns = {"waypointId"}),
#ForeignKey(entity = POIRoute.class, parentColumns = {"id"}, childColumns = {"routeId"})
})
public class RouteWaypoint {
private int waypointId;
private int routeId;
// I want this attribute inside the POIWaypoint class
#ColumnInfo(name = "index_of_route")
private int indexOfRoute;
public int getWaypointId() {
return waypointId;
}
public void setWaypointId(int waypointId) {
this.waypointId = waypointId;
}
public int getRouteId() {
return routeId;
}
public void setRouteId(int routeId) {
this.routeId = routeId;
}
}
POIRoute:
#Entity
public class POIRoute{
private String name;
private String description;
#PrimaryKey(autoGenerate = true)
private int id;
private boolean user_generated;
private int parentId;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public boolean isUser_generated() {
return user_generated;
}
public void setUser_generated(boolean user_generated) {
this.user_generated = user_generated;
}
public int getParentId() {
return parentId;
}
public void setParentId(int parentId) {
this.parentId = parentId;
}
}
POIWaypoint (please ignore the position attribute it isn't finished):
#Entity
public class POIWaypoint {
#PrimaryKey(autoGenerate = true)
private long id;
#ColumnInfo(name = "long_description")
private String longDescription;
private String title;
#ColumnInfo(name = "short_description")
private String shortDescription;
// use converter: https://developer.android.com/training/data-storage/room/referencing-data
#Ignore
private GeoPoint position;
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public GeoPoint getPosition() {
return position;
}
public void setPosition(GeoPoint position) {
this.position = position;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getShortDescription() {
return shortDescription;
}
public void setShortDescription(String shortDescription) {
this.shortDescription = shortDescription;
}
public String getLongDescription() {
return longDescription;
}
public void setLongDescription(String longDescription) {
this.longDescription = longDescription;
}

I solved my problem by manage the relation by myself. I changed my RouteDao to an abstract class to insert my own method, which manages part of the junction table by itself:
RouteDao:
private RouteDatabase database;
public RouteDao(RouteDatabase database) {
this.database = database;
}
#Query("Select * from POIRoute")
public abstract List<POIRoute> getRoutes();
#Query("SELECT * FROM POIRoute WHERE id = :id")
public abstract POIRoute getRoute(int id);
#Insert
abstract void insertRouteWithWaypoints(RouteWithWaypoints routeWithWaypoints);
public List<RouteWithWaypoints> getRoutesWithWaypoints() {
List<POIRoute> routes = this.getRoutes();
List<RouteWithWaypoints> routesWithWaypoints = new LinkedList<>();
for (POIRoute r : routes) {
routesWithWaypoints.add(new RouteWithWaypoints(r, database.wayPointDao().getWaypointsFromRoute(r.getId())));
}
return routesWithWaypoints;
}
public RouteWithWaypoints getRouteWithWaypoints(int id) {
POIRoute route = this.getRoute(id);
RouteWithWaypoints routeWithWaypoints = null;
if (route != null) {
routeWithWaypoints = new RouteWithWaypoints(route, database.wayPointDao().getWaypointsFromRoute(route.getId()));
}
return routeWithWaypoints;
}
WayPointDao:
#Query("SELECT * FROM POIWaypoint")
POIWaypoint getWaypoints();
#Query("SELECT * FROM POIWaypoint WHERE id = :id")
POIWaypoint getWaypoint(long id);
#Query("SELECT pw.*, rw.index_of_route as 'index' FROM POIWaypoint as pw Join RouteWaypoint as rw on (rw.waypointId = pw.id) where rw.routeId = :id order by 'index' ASC")
List<POIRouteStep> getWaypointsFromRoute(int id);

Are entities relationship correct?

In my project I try yo use Spring data Jpa. My find methods(findById, findAll) works correctly, but delete and save method works with problems. Delete method delete only from duck table. Save doesn't work:
Exception in thread "main" org.springframework.orm.jpa.JpaObjectRetrievalFailureException: Unable to find springdata.entities.FrogJpa with id 2; nested exception is javax.persistence.EntityNotFoundException: Unable to find springdata.entities.FrogJpa with id 2
I have 2 entities: Frog and Duck. Every ducks have 1 Frog(OneToOne). There are problems with entities relationship?
There are my entities class:
#Entity
#Table(name = "DUCKS")
public class DuckJpa implements Serializable {
#Id
private int id;
#Column(name = "NAME")
private String name;
#Column(name = "FLY")
private String flyBehavior;
#Column(name = "QUACK")
private String quackBehavior;
#OneToOne(optional = false)
#JoinColumn(name = "FROG_ID", unique = true, nullable = false, updatable = false)
private FrogJpa frogJpa;
public void setId(int id) {
this.id = id;
}
public void setName(String name) {
this.name = name;
}
public void setFlyBehavior(String flyBehavior) {
this.flyBehavior = flyBehavior;
}
public void setQuackBehavior(String quackBehavior) {
this.quackBehavior = quackBehavior;
}
public void setFrogJpa(FrogJpa frogJpa) {
this.frogJpa = frogJpa;
}
public int getId() {
return id;
}
public String getName() {
return name;
}
public String getFlyBehavior() {
return flyBehavior;
}
public String getQuackBehavior() {
return quackBehavior;
}
public FrogJpa getFrogJpa() {
return frogJpa;
}
And Frog:
#Entity
#Table(name = "FROGS")
public class FrogJpa {
#OneToOne(optional = false, mappedBy = "frogJpa")
private DuckJpa duckJpa;
#Id
private int id;
#Column(name = "name")
private String name;
public void setId(int id) {
this.id = id;
}
public void setName(String name) {
this.name = name;
}
public void setDuckJpa(DuckJpa duckJpa) {
this.duckJpa = duckJpa;
}
public int getId() {
return id;
}
public String getName() {
return name;
}
public DuckJpa getDuckJpa() {
return duckJpa;
}
}
My service class:
public interface DuckService {
List<DuckJpa> findAll();
Optional<DuckJpa> findById(Integer i);
DuckJpa save(DuckJpa duckJpa);
void delete(DuckJpa duckJpa);
}
And it's implementation:
#Service("springJpaDuckService")
#Transactional
public class DuckServiceImpl implements DuckService {
#Autowired
private DuckJpaRepository duckJpaRepository;
#Transactional(readOnly = true)
public List<DuckJpa> findAll() {
return new ArrayList<>(duckJpaRepository.findAll());
}
#Override
public Optional<DuckJpa> findById(Integer i) {
return duckJpaRepository.findById(i);
}
#Override
public DuckJpa save(DuckJpa duckJpa) {
duckJpaRepository.save(duckJpa);
return duckJpa;
}
#Override
public void delete(DuckJpa duckJpa) {
duckJpaRepository.delete(duckJpa);
}

Use #OneToOne(cascade=CascadeType.ALL, fetch = FetchType.LAZY).
For more information please refer What is cascading in Hibernate?

Data insertion in database using jpa issueing error

I am new to the JPA world. Here I have tried to make a simple POS. The problem is that when there is no predefined value in tables although the PK is auto-incremented, data is not being inserted into DB. But if I set a predefined row into the tables then there are no issues and data is being inserted successfully. please help me.
The following are my Java classes, and I am using Mysql for DB.
#Entity
#Table(name = "card_payment")
public class Card_payment {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
int id;
#OneToOne(cascade = CascadeType.ALL)
#JoinColumn(name = "order_id")
private Orders order;
#Column(name = "issuing_bank")
String issuing_bank;
#Column(name = "card_type")
String card_type;
#Column(name = "card_expiry_date")
String card_expiry_date;
#Column(name = "amount")
int amount;
public Card_payment() {
super();
}
public Orders getOrder() {
return order;
}
public void setOrder(Orders order) {
this.order = order;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getIssuing_bank() {
return issuing_bank;
}
public void setIssuing_bank(String issuing_bank) {
this.issuing_bank = issuing_bank;
}
public String getCard_type() {
return card_type;
}
public void setCard_type(String card_type) {
this.card_type = card_type;
}
public String getCard_expiry_date() {
return card_expiry_date;
}
public void setCard_expiry_date(String card_expiry_date) {
this.card_expiry_date = card_expiry_date;
}
public int getAmount() {
return amount;
}
public void setAmount(int amount) {
this.amount = amount;
}
}
#Entity
#Table(name = "customer")
public class Customer {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
int id;
#Column(name = "name")
String name;
#Column(name = "mobile_no")
long mobile_no;
#Column(name = "address")
String address;
#OneToMany(mappedBy = "customer", cascade = CascadeType.ALL,
fetch=FetchType.LAZY)
private List<Orders> orders;;
public Customer() {
super();
}
public List<Orders> getOrders() {
return orders;
}
public void setOrders(List<Orders> orders) {
this.orders = orders;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public long getMobile_no() {
return mobile_no;
}
public void setMobile_no(long mobile_no) {
this.mobile_no = mobile_no;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
}
#Entity
#Table(name = "Item")
public class Item {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
int id;
#Column(name = "name")
String name;
#Column(name = "unit")
String unit;
#Column(name = "stock_quantity")
int stock_quantity;
#Column(name = "reorder_level")
int reorder_level;
#Column(name = "unit_price")
int unit_price;
#Column(name = "tax_percentage")
float tax_percentage;
#OneToMany(mappedBy = "item", cascade = CascadeType.ALL,
fetch=FetchType.LAZY)
private List<Orderline> orderLines;
public Item() {
super();
}
public List<Orderline> getOrderLines() {
return orderLines;
}
public void setOrderLines(List<Orderline> orderLines) {
this.orderLines = orderLines;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getUnit() {
return unit;
}
public void setUnit(String unit) {
this.unit = unit;
}
public int getStock_quantity() {
return stock_quantity;
}
public void setStock_quantity(int stock_quantity) {
this.stock_quantity = stock_quantity;
}
public int getReorder_level() {
return reorder_level;
}
public void setReorder_level(int reorder_level) {
this.reorder_level = reorder_level;
}
public int getUnit_price() {
return unit_price;
}
public void setUnit_price(int unit_price) {
this.unit_price = unit_price;
}
public float getTax_percentage() {
return tax_percentage;
}
public void setTax_percentage(float tax_percentage) {
this.tax_percentage = tax_percentage;
}
}
#Entity
#Table(name = "OrderLine")
public class Orderline {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
int id;
#ManyToOne
#JoinColumn(name = "itemId")
private Item item;
#ManyToOne
#JoinColumn(name = "orderId")
private Orders orders;
#Column(name = "unit_cost")
float unit_cost;
#Column(name = "unit")
int unit;
#Column(name = "tax_percentage")
float tax_percentage;
#Column(name = "quantity")
int quantity;
#Column(name = "amount")
int amount;
#Column(name = "tax_amount")
float tax_amount;
#Column(name = "line_total")
int line_total;
public Orderline() {
super();
}
public Item getItem() {
return item;
}
public void setItem(Item item) {
this.item = item;
}
public Orders getOrders() {
return orders;
}
public void setOrders(Orders orders) {
this.orders = orders;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public float getUnit_cost() {
return unit_cost;
}
public void setUnit_cost(float unit_cost) {
this.unit_cost = unit_cost;
}
public int getUnit() {
return unit;
}
public void setUnit(int unit) {
this.unit = unit;
}
public float getTax_percentage() {
return tax_percentage;
}
public void setTax_percentage(float tax_percentage) {
this.tax_percentage = tax_percentage;
}
public int getQuantity() {
return quantity;
}
public void setQuantity(int quantity) {
this.quantity = quantity;
}
public int getAmount() {
return amount;
}
public void setAmount(int amount) {
this.amount = amount;
}
public float getTax_amount() {
return tax_amount;
}
public void setTax_amount(float tax_amount) {
this.tax_amount = tax_amount;
}
public int getLine_total() {
return line_total;
}
public void setLine_total(int line_total) {
this.line_total = line_total;
}
#Entity
#Table(name = "orders")
public class Orders {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
int id;
#ManyToOne
#JoinColumn(name = "customerId")
private Customer customer;
#Column(name = "order_date")
String order_date;
#Column(name = "delivery_address")
String delivery_address;
#Column(name = "total")
long total;
#OneToMany(mappedBy = "orders", cascade = CascadeType.ALL,
fetch=FetchType.LAZY)
private List<Orderline> orderlines;
#OneToOne(mappedBy = "order")
private Cash_payment cash_payment;
#OneToOne(mappedBy = "order")
private Card_payment card_payment;
#OneToOne(mappedBy = "order")
private Cheque_payment cheque_payment;
public Orders() {
super();
}
public Cash_payment getCash_payment() {
return cash_payment;
}
public void setCash_payment(Cash_payment cash_payment) {
this.cash_payment = cash_payment;
}
public Card_payment getCard_payment() {
return card_payment;
}
public void setCard_payment(Card_payment card_payment) {
this.card_payment = card_payment;
}
public Cheque_payment getCheque_payment() {
return cheque_payment;
}
public void setCheque_payment(Cheque_payment cheque_payment) {
this.cheque_payment = cheque_payment;
}
public List<Orderline> getOrderlines() {
return orderlines;
}
public void setOrderlines(List<Orderline> orderlines) {
this.orderlines = orderlines;
}
public Customer getCustomer() {
return customer;
}
public void setCustomer(Customer customer) {
this.customer = customer;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getOrder_date() {
return order_date;
}
public void setOrder_date(String order_date) {
this.order_date = order_date;
}
public String getDelivery_address() {
return delivery_address;
}
public void setDelivery_address(String delivery_address) {
this.delivery_address = delivery_address;
}
public long getTotal() {
return total;
}
public void setTotal(long total) {
this.total = total;
}
}
public class JPAExample {
private static EntityManager entityManager = EntityManagerUtil.getEntityManager();
public static void main(String[] args) {
JPAExample example = new JPAExample();
entityManager.getTransaction().begin();
Orders order = new Orders();
order.setOrder_date("2019/05/05");
order.setTotal(1000);
order.setDelivery_address("kolkata");
Item item = new Item();
item.setName("cream");
item.setReorder_level(10);
item.setUnit_price(10);
item.setUnit("kg");
item.setTax_percentage((float) 12.5);
item.setStock_quantity(20);
item.setReorder_level(5);
Orderline orderline = new Orderline();
orderline.setAmount(1);
orderline.setItem(item);
orderline.setLine_total(200);
orderline.setQuantity(1);
List<Orderline> orderlns = new ArrayList<>();
orderlns.add(orderline);
item.setOrderLines(orderlns);
Customer customer = new Customer();
customer.setId(1234);
customer.setName("Tanusha");
customer.setMobile_no(Long.valueOf("9609"));
customer.setAddress("u-86, garia");
orderline.setOrders(order);
List<Orderline> orderLinesList = new ArrayList<>();
orderLinesList.add(orderline);
order.setOrderlines(orderLinesList);
order.setCustomer(customer);
List<Orders> orderList = new ArrayList<>();
orderList.add(order);
customer.setOrders(orderList);
Card_payment cp = new Card_payment();
cp.setAmount(200);
cp.setCard_expiry_date("2019/05/05");
cp.setCard_type("visa");
cp.setIssuing_bank("SBI");
cp.setOrder(order);
order.setCard_payment(cp);
entityManager.merge(order);
try {
entityManager.getTransaction().commit();
} catch (Exception e) {
entityManager.getTransaction().rollback();
}
}
}

Jackson is returning duplicate rows

I am trying to return json from these two entity classes.
Questions.java
#Entity
public class Questions {
#Id
#Column(name = "id")
private int id;
#Column(name = "question")
private String question;
#Column(name = "type")
private String type;
#Column(name = "description")
private String description;
#Column(name = "param")
private String param;
#Column(name = "maxlength")
private int maxlength;
#Column(name = "dependency")
private String dependency;
#OneToMany(mappedBy = "questions",targetEntity = Answers.class, cascade = CascadeType.ALL)
private Set<Answers> answers = new HashSet<>();
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getQuestion() {
return question;
}
public void setQuestion(String question) {
this.question = question;
}
public String getType() {
return type;
}
public void setType(String type) {
this.type = type;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public String getParam() {
return param;
}
public void setParam(String param) {
this.param = param;
}
public int getMaxlength() {
return maxlength;
}
public void setMaxlength(int maxlength) {
this.maxlength = maxlength;
}
public String getDependency() {
return dependency;
}
public Set<Answers> getAnswers() {
return answers;
}
public void setAnswers(Set<Answers> answers) {
this.answers = new HashSet<>(answers);
for(Answers answers1:answers){
answers1.setQuestions(this);
}
}
public void setDependency(String dependency) {
this.dependency = dependency;
}
}
Answers.java
#Entity
public class Answers {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
private int id;
#Column(name = "ans_label")
private String ans_label;
#Column(name = "ans_value")
private int ans_value;
#Column(name = "ans_weightage")
private int ans_weightage;
#Column(name = "is_default")
private int is_default;
#ManyToOne(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
#JoinColumn(name = "ques_id", nullable = false)
private Questions questions;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getAns_label() {
return ans_label;
}
public void setAns_label(String ans_label) {
this.ans_label = ans_label;
}
public int getAns_value() {
return ans_value;
}
public void setAns_value(int ans_value) {
this.ans_value = ans_value;
}
public int getAns_weightage() {
return ans_weightage;
}
public void setAns_weightage(int ans_weightage) {
this.ans_weightage = ans_weightage;
}
public int getIs_default() {
return is_default;
}
public void setIs_default(int is_default) {
this.is_default = is_default;
}
public Questions getQuestions() {
return questions;
}
public void setQuestions(Questions questions) {
this.questions = questions;
}
}
my controller looks like this.
SaveApiController
#RequestMapping("/getData")
public #ResponseBody List<Questions> getData(){
List<Questions> questionss=saveApiServices.getQuestions();
return questionss;
}
The json result i am currently getting has bunch of repeated values.
[{"id":1,"question":"१. व्यक्तिको पुरा नाम थर?", "type":"input_edittext",
"description":"","param":"smalltext","maxlength":20,"dependency":"",
"answers":
[{"id":0,"ans_label":"मुली","ans_value":1,"ans_weightage":0,"is_default":0,
"questions":{"id":1,"question":"१. व्यक्तिको पुरा नाम थर?",
"type":"input_edittext","description":"","param":"smalltext","maxlength":20
,"dependency":"","answers":[{"id":0,"ans_label":"मुली","ans_value":1,
"ans_weightage":0,"is_default":0,"questions":{"id":1,
"question":"१. व्यक्तिको पुरा नाम थर ?","type":"input_edittext",
"description":"","param":"smalltext","maxlength":20,"dependency":"",
"answers":[{"id":0,"ans_label":"मुली",
"ans_value":1,"ans_weightage":0,"is_default":0,"questions":{"id":1,
"question":"१. व्यक्तिको पुरा नाम थर ?","type":"input_edittext",
"description":"","param":"smalltext","maxlength":20,"dependency":"",
my database has only one row inserted. and on my controller there is only one list of questions found. but whenever json output is thrown it repeats a lot of same rows like in the above json sample.
what might be the problems? if you can't find the complete solution can you please suggest me the reason behind the duplication of the same values in json format?

Jackson is getting in a loop here. Your Questions class has a link to Answers and that class refers back to Questions.
Solution
Mark the questions field or the getter in the Answers class as #JsonIgnored.

You can try #JsonManagedReference and #JsonBackReference annotations
For Jackson to work well, one of the two sides of the relationship should not be serialized, in order to avoid the infite loop that causes your stackoverflow error.
#OneToMany(mappedBy = "questions",targetEntity = Answers.class, cascade = CascadeType.ALL)
#JsonManagedReference
private Set<Answers> answers = new HashSet<>();
#ManyToOne(cascade = CascadeType.ALL, fetch = FetchType.EAGER)
#JoinColumn(name = "ques_id", nullable = false)
#JsonBackReference
private Questions questions;
Or
If not interested in getting some entity data just use #JsonIgnore in any one of the class

insert Hibernate Many to one in table having foreign key

I am facing problem while inserting. I want to save the details in result table without saving the foreign key parameters in parent table.
there are three pojo classes:
#Entity
#Table(name="course")
public class Course implements Serializable{
private static final long serialVersionUID = 1L;
#Id
#Column( name="id")
#GeneratedValue(strategy=GenerationType.AUTO)
private int id;
#Column(name="course_id",nullable = false)
private String course_id;
#Column( name="course_name")
private String course_name;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getCourse_id() {
return course_id;
}
public void setCourse_id(String course_id) {
this.course_id = course_id;
}
public String getCourse_name() {
return course_name;
}
public void setCourse_name(String course_name) {
this.course_name = course_name;
}
**#OneToMany(fetch = FetchType.EAGER, mappedBy = "course")
private Set<Result> result = new HashSet<Result>(0);
public Set<Result> getResult() {
return this.result;
}
public void setResult(Set<Result> result) {
this.result = result;
}**
}
The second class is Student.java
#Entity
#Table(name ="student")
public class Student implements Serializable {
/**
*
*/
private static final long serialVersionUID = 1L;
//Attribute----------------------------------
#Id
#Column(name="id")
#GeneratedValue(strategy=GenerationType.AUTO)
private int id;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
//Attribute----------------------------------
#Column(name="student_id", nullable=false)
private long student_id;
public long getStudent_id() {
return student_id;
}
public void setStudent_id(long student_id) {
this.student_id = student_id;
}
//Attribute----------------------------------
#Column(name="student_name")
private String student_name;
public String getStudent_name() {
return student_name;
}
public void setStudent_name(String student_name) {
this.student_name = student_name;
}
//Attribute----------------------------------
#Column(name="student_contact_number")
private long student_contact_number;
public long getStudent_contact_number() {
return student_contact_number;
}
public void setStudent_contact_number(long student_contact_number) {
this.student_contact_number = student_contact_number;
}
//This is for the foreign key element in the Result.java POJO class
#OneToMany(fetch = FetchType.LAZY,cascade = {CascadeType.ALL}, mappedBy = "student")
private Set<Result> result = new HashSet<Result>(0);
public Set<Result> getResult() {
return this.result;
}
public void setResult(Set<Result> result) {
this.result = result;
}
}
Third is Result.java which contains the foreign keys
#Entity
#Table(name="result")
public class Result implements Serializable{
private static final long serialVersionUID = 1L;
#Id
#Column(name="id")
#GeneratedValue(strategy = GenerationType.AUTO)
private int id;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
#Column(name="semester")
private int semester;
public int getSemester() {
return semester;
}
public void setSemester(int semester) {
this.semester = semester;
}
#Column(name="marks")
private int marks;
public int getMarks() {
return marks;
}
public void setMarks(int marks) {
this.marks = marks;
}
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "student_id", nullable = false)
private Student student;
public Student getStudent() {
return this.student;
}
public void setStudent(Student student_id) {
this.student = student_id;
}
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "course_id", nullable = false)
private Course course;
public Course getCourse() {
return this.course;
}
public void setCourse(Course course) {
this.course = course;
}
}
Now the code I used to insert is like this:
Session session;
Transaction t;
Query query;
Configuration cfg=new Configuration();
cfg.configure("hibernate.cfg.xml");
//#SuppressWarnings("deprecation")
SessionFactory factory=cfg.buildSessionFactory();
session=factory.openSession();
t=session.beginTransaction();
Result result;
Course cs;
Student st;
for(int i=0; i<jsrm.get(0).size(); i++)
{
result=new Result();
cs= new Course();
st=new Student();
cs.setCourse_id(jsrm.get(0).get(i).getcourse_id());
st.setStudent_id(Integer.parseInt(jsrm.get(0).get(i).getstudent_id()));
result.setSemester(Integer.parseInt(jsrm.get(0).get(i).getsemester()));
result.setMarks(Integer.parseInt(jsrm.get(0).get(i).getmarks()));
result.setCourse(cs);
result.setStudent(st);
session.save(result);
}
t.commit();//transaction is committed
session.close();
The error is
org.hibernate.TransientPropertyValueException: Not-null property references a transient value - transient instance must be saved before
current operation: Result.course -> Course
Is there a way to store the data without saving the course and student.