hibernate - Grails的hasOne和hasMany具有相同的域和级联操作

Question

有什么办法可以使以下结构:

class Parent {
   String name
   static hasOne = [firstChild: Child]
   static hasMany = [otherChildren: Child]
}


class Child{
   String name
   static belongsTo = [parent: Parent]
}

现在，当我尝试运行简单的代码时:

Parent p = new Parent(name: "parent", firstChild: new Child(name: 'child'))
p.addToOtherChildren(new Child(name: "child2"));
p.addToOtherChildren(new Child(name: "child3"));
p.save(flush: true)

它保存了对象，但是当我尝试对Parent进行列表操作时，会引发以下错误:

org.springframework.orm.hibernate4.HibernateSystemException: More than one row with the given identifier was found: 2, for class: test.Child; nested exception is org.hibernate.HibernateException: More than one row with the given identifier was found: 2, for class: test.Child

这里的问题是hasOne会将Parent ID存储在Child中，hasMany与belongsTo一样，现在不止一个子实例具有相同的Parent ID，因此很难确定哪个是firstChild。

我也尝试过this solution，但它抛出此异常:
org.springframework.dao.InvalidDataAccessApiUsageException: Not-null property references a transient value - transient instance must be saved before current operation : test.Child.parent -> test.Parent; nested exception is org.hibernate.TransientPropertyValueException: Not-null property references a transient value - transient instance must be saved before current operation : test.Child.parent -> test.Parent
有什么更好的方法吗，还是我做错了什么？

我想与父级联保存firstChild和otherChildren。

Answer 1

根据错误消息( transient )，添加子级之前需要先o​​jit_code save:

 Parent p = new Parent(name: "parent")

 if(p.save()){
     p.firstChild=new Child(name: 'child');
     p.addToOtherChildren(new Child(name: "child2"));
     p.addToOtherChildren(new Child(name: "child3"));
     p.save(flush: true)
}