mappedBy reference an unknown target entity property

Question

I am having an issue in setting up a one to many relationship in my annotated object   I have the following    MappedSuperclass public abstract class MappedModel        Id      GeneratedValue strategy GenerationType AUTO       Column name  id  nullable false unique true      private Long mId    then this   Entity  Table name  customer   public class Customer extends MappedModel implements Serializable                          private static final long serialVersionUID   -2543425088717298236L          The collection of stores          OneToMany mappedBy    customer   cascade   CascadeType ALL  fetch   FetchType LAZY    private Collection lt Store gt  stores    and this   Entity  Table name  store   public class Store extends MappedModel implements Serializable                          private static final long serialVersionUID   -9017650847571487336L         many stores have a single customer        ManyToOne fetch   FetchType LAZY     JoinColumn  name  customer id  referencedColumnName  id  nullable false unique true    private Customer mCustomer    what am i doing incorrect here

User · Answer

I know the answer by  Pascal Thivent has solved the issue  I would like to add a bit more to his answer to others who might be surfing this thread    If you are like me in the initial days of learning and wrapping your head around the concept of using the  OneToMany annotation with the  mappedBy  property  it also means that the other side holding the  ManyToOne annotation with the  JoinColumn is the  owner  of this bi-directional relationship   Also  mappedBy takes in the instance name  mCustomer in this example  of the Class variable as an input and not the Class-Type  ex Customer  or the entity name Ex customer     BONUS    Also  look into the orphanRemoval property of  OneToMany annotation  If it is set to true  then if a parent is deleted in a bi-directional relationship  Hibernate automatically deletes it s children

User · Answer

public class User implements Serializable        private static final long serialVersionUID   1L        Id      Column name    USER ID       Long userId        OneToMany fetch   FetchType LAZY  mappedBy    sender   cascade   CascadeType ALL      List lt Notification gt  sender        OneToMany fetch   FetchType LAZY  mappedBy    receiver   cascade   CascadeType ALL      List lt Notification gt  receiver     public class Notification implements Serializable        private static final long serialVersionUID   1L        Id       Column name    NOTIFICATION ID       Long notificationId        Column name    TEXT       String text        Column name    ALERT STATUS        Enumerated EnumType STRING      AlertStatus alertStatus   AlertStatus NEW        ManyToOne fetch   FetchType LAZY       JoinColumn name    SENDER ID        JsonIgnore     User sender        ManyToOne fetch   FetchType LAZY       JoinColumn name    RECEIVER ID        JsonIgnore     User receiver      What I understood from the answer  mappedy  sender  value should be the same in the notification model  I will give you an example    User model    OneToMany fetch   FetchType LAZY  mappedBy      sender     cascade   CascadeType ALL      List lt Notification gt  sender        OneToMany fetch   FetchType LAZY  mappedBy      receiver     cascade   CascadeType ALL      List lt Notification gt  receiver    Notification model    OneToMany fetch   FetchType LAZY  mappedBy    sender   cascade   CascadeType ALL      List lt Notification gt    sender          OneToMany fetch   FetchType LAZY  mappedBy    receiver   cascade   CascadeType ALL      List lt Notification gt    receiver      I gave bold font to user model and notification field  User model mappedBy  sender   should be equal to notification List  sender  and mappedBy  receiver  should be equal to notification List  receiver  If not  you will get error

User · Answer

The mappedBy attribute is referencing customer while the property is mCustomer  hence the error message  So either change your mapping into       The collection of stores      OneToMany mappedBy    mCustomer   cascade   CascadeType ALL  fetch   FetchType LAZY  private Collection lt Store gt  stores    Or change the entity property into customer  which is what I would do    The mappedBy reference indicates  Go look over on the bean property named  customer  on the thing I have a collection of to find the configuration

[java] mappedBy reference an unknown target entity property

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