CODEWITHSUNDEEP
javaspringspring-boothibernatejpa
gaurab pokharel
gaurab pokharel

Reputation: 11

I'm trying to use @OneToMany relationship in Springboot Jpa

I am trying to use the @OneToMany relationship in my project but got the error: org.hibernate.AnnotationException: Illegal attempt to map a non collection as a @OneToMany, @ManyToMany or @CollectionOfElements: com.digitalProfile.digitalProfile.entity.Education.faculty.

I am using JDK 11 My Education.java model looks like this :

package com.digitalProfile.digitalProfile.entity;

import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.OneToMany;
import javax.persistence.OneToOne;
import javax.persistence.Table;

@Entity
@Table(name="Education")
public class Education extends BaseEntity {

private String name;
private String establishDateNepali;
private String establishDateEnglish;
@OneToOne
private OwnedType ownedType;
private double area;
private int teacherCount;
private int studentCount;
private int staffCount;
@OneToOne
private AcademicLevel academicLevel;

@OneToMany(mappedBy = "education", fetch = FetchType.LAZY,
        cascade = CascadeType.ALL)
private Faculty faculty;

private String province;
private String district;
private String munvdc;
private String ward;
private String gauntole;
private String streetname;
private String city;
  
  

//getter setter

and Faculty.java look like this :

package com.digitalProfile.digitalProfile.entity;

import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;

@Entity
@Table
public class Faculty extends BaseEntity{

@ManyToOne(fetch = FetchType.LAZY, optional = false)
@JoinColumn(name = "education_id", nullable = false)
private Education education;

private String name;

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

}

and base entity: package com.digitalProfile.digitalProfile.entity;

import java.util.Date;

import javax.persistence.Column;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.MappedSuperclass;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;

import org.hibernate.annotations.CreationTimestamp;
import org.hibernate.annotations.UpdateTimestamp;

@MappedSuperclass
public class BaseEntity {

@Id
@Column(nullable = false, unique = true)
@GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;

@Temporal(TemporalType.TIMESTAMP)
@CreationTimestamp
@Column(updatable = false)
private Date dateCreated;

@Temporal(TemporalType.TIMESTAMP)
@UpdateTimestamp
private Date dateUpdated;

public int getId() {
    return id;
}

public void setId(int id) {
    this.id = id;
}

public Date getDateCreated() {
    return dateCreated;
}

public void setDateCreated(Date dateCreated) {
    this.dateCreated = dateCreated;
}

public Date getDateUpdated() {
    return dateUpdated;
}

public void setDateUpdated(Date dateUpdated) {
    this.dateUpdated = dateUpdated;
}

}

Upvotes: 1

Views: 78

Answers (2)

Preeti
Preeti

Reputation: 222

If you are saying Education can have multiple faculties, then it should be defined as

@OneToMany(mappedBy = "education", fetch = FetchType.LAZY,
        cascade = CascadeType.ALL)
private Set<Faculty> faculties;

Upvotes: 1

user6073886
user6073886

Reputation:

You currently have defined your Education class to have a single reference variable to Faculty:

public class Education extends BaseEntity {

    private Faculty faculty;

}

But if you want to have a OneToMany relationship From Education To Faculty that means that one Education object needs to have references to multiple Faculty objects. So you need to change your data structure so that your Education class can hold multiple references to Faculty objects.

This is usually done by defining the field as a Collection like List:

public class Education extends BaseEntity {

    private List<Faculty> faculties;

}

Upvotes: 2

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