grails - 如何在grails中建立一对一的双向关系？

Question

我有两个域类，并且希望它们之间具有一对一的BIDIRECTIONAL关系。我写:

class Person {

  Book book;

  String name
  Integer age
  Date lastVisit

  static constraints = {
    book unique: true  // "one-to-one". Without that = "Many-to-one".
  }

}
 

class Book {

  String title
  Date releaseDate
  String ISBN

  static belongsTo = [person:Person] // it makes relationship bi-directional regarding the grails-docs 
}


 

So, i want to have bi-directional, i could NOT find link from Book to Person in generated SQL:

CREATE TABLE `book` (
  `id` bigint(20) NOT NULL AUTO_INCREMENT,
  `version` bigint(20) NOT NULL,
  `isbn` varchar(255) NOT NULL,
  `release_date` datetime NOT NULL,
  `title` varchar(255) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=2 DEFAULT CHARSET=latin1

那么，那意味着它不是双向的吗？如何做双向？

Answer 1

checkout hasOne属性，在其中定义hasOne和belongsTo的类取决于您要存储FK的位置，请检查有关hasOne的此grails文档:
http://www.grails.org/doc/latest/ref/Domain%20Classes/hasOne.html