jpa - Java Hibernate with Persistence Question---if FetchType is not defined, what is the default method?

Question

I am new to Hibernate and JPA.

I wrote some functions, initially, I set fetch = FetchType.LAZY in the entity class. But it gave me error:

"org.hibernate.LazyInitializationException: could not initialize proxy - no Session"

@OneToMany(cascade = CascadeType.ALL, mappedBy = "logins", fetch=FetchType.LAZY,targetEntity=Invoice.class)
public List<Invoice> getInvoiceList() {
    return invoiceList;
}

public void setInvoiceList(List<Invoice> invoiceList) {
    this.invoiceList = invoiceList;
}

Then I changed it to fetch = FetchType.EAGER, and it worked fine.

I am wondering　what happen if I don't declare FetchType, does Hibernate determine itself which method to use? Or is it defaulted by EAGER?

@OneToMany(cascade = CascadeType.ALL, mappedBy = "logins", fetch=FetchType.EAGER,targetEntity=Invoice.class)
public List<Invoice> getInvoiceList() {
    return invoiceList;
}

public void setInvoiceList(List<Invoice> invoiceList) {
    this.invoiceList = invoiceList;
}

Answer 1

From the JPA 2.0 spec, the defaults are like so:

• OneToMany: LAZY
• ManyToOne: EAGER
• ManyToMany: LAZY
• OneToOne: EAGER
• Columns : EAGER