mappedBy reference an unknown target entity property

问题

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<Store> 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

回答1:

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<Store> 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."

回答2:

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.

来源：https://stackoverflow.com/questions/4011472/mappedby-reference-an-unknown-target-entity-property

标签

java

hibernate

orm

hibernate-annotations