Grails GORM - 在父母之前保存孩子答案

【问题标题】：Grails GORM - Saves child before parentGrails GORM - 在父母之前保存孩子
【发布时间】：2014-10-27 05:14:13
【问题描述】：

我有几个具有子父关系的类，但是，当尝试保存所有内容时，Grails GORM 首先保存子，最终引发以下错误：

ORA-02291: integrity constraint violated - parent key not found

这是我的类的基本代码表示：

class Request
{
  // Mapping definitions
  static mapping = {
    table(name: 'FORMS_REQUEST')
    tablePerHierarchy(false)
    id(length: 20, precision: 20, scale: 0, generator: 'sequence', params: [sequence: 'FORMS_REQUEST_SEQ'])       
  }

  // Properties
  Timestamp version
  Form form
  Date submittedTime
}

abstract class Form
{
  // Mapping definitions
  static mapping = {
    table(name: 'FORMS_FORM')
    tablePerHierarchy(false)
    id(length: 20, precision: 20, scale: 0, generator: 'sequence', params: [sequence: 'FORMS_FORM_SEQ'])
  }

  // Relationship definitions
  static belongsTo = [request: Request]

  // Properties
  Timestamp version
}

class AccessForm extends Form
{
  // Mapping definitions
  static mapping = {
    table(name: 'FORMS_ACCESS_FORM')
    id(length: 20, precision: 20, scale: 0, generator: 'sequence', params: [sequence: 'FORMS_ACCESS_FORM_SEQ'])
  }

  // Relationship definitions
  static hasMany = [adGroups: AccessFormAD, printers: AccessFormPrinter]

  // Properties
  List adGroups
  List printers
}

class AccessFormAD
{
  // Mapping definitions
  static mapping = {
    table(name: 'FORMS_ACCESS_FORM_AD')
    id(length: 20, precision: 20, scale: 0, generator: 'sequence', params: [sequence: 'FORMS_ACCESS_FORM_AD_SEQ'])
  }

  // Relationship definitions
  static belongsTo = [accessForm: AccessForm]

  // Properties
  Timestamp version
}

class AccessFormPrinter
{
  // Mapping definitions
  static mapping = {
    table(name: 'FORMS_ACCESS_FORM_PRINTER')
    id(length: 20, precision: 20, scale: 0, generator: 'sequence', params: [sequence: 'FORMS_ACCESS_FORM_PRINTER_SEQ'])
  }

  // Relationship definitions
  static belongsTo = [accessForm: AccessForm]

  // Properties
  Timestamp version
}

使用正确的数据等创建所有类并调用以下内容后：

request.save(flush: true)

我收到上述错误。日志显示 Hibernate 生成的以下 SQL 语句：

Hibernate: select FORMS_REQUEST_SEQ.nextval from dual
Hibernate: select FORMS_FORM_SEQ.nextval from dual
Hibernate: select FORMS_ACCESS_FORM_AD_SEQ.nextval from dual
Hibernate: select FORMS_ACCESS_FORM_AD_SEQ.nextval from dual
Hibernate: select FORMS_ACCESS_FORM_AD_SEQ.nextval from dual
Hibernate: select FORMS_ACCESS_FORM_AD_SEQ.nextval from dual
Hibernate: select FORMS_ACCESS_FORM_AD_SEQ.nextval from dual
Hibernate: select FORMS_ACCESS_FORM_AD_SEQ.nextval from dual
Hibernate: select FORMS_ACCESS_FORM_AD_SEQ.nextval from dual
Hibernate: select FORMS_ACCESS_FORM_AD_SEQ.nextval from dual
Hibernate: select FORMS_ACCESS_FORM_AD_SEQ.nextval from dual
Hibernate: select FORMS_ACCESS_FORM_AD_SEQ.nextval from dual
Hibernate: select FORMS_ACCESS_FORM_AD_SEQ.nextval from dual
Hibernate: select FORMS_ACCESS_FORM_AD_SEQ.nextval from dual
Hibernate: insert into FORMS_ACCESS_FORM_AD (version, checked, DN, type, access_form_id, ad_groups_idx, id) values (?, ?, ?, ?, ?, ?, ?)
Sep. 02 2014 @ 03:58:06 PM - class spi.SqlExceptionHelper - ORA-02291: integrity constraint (FK_954TU4QUPD4QE7H72XGVXSTKV) violated - parent key not found

首先在父母之前保存子对象，这可以解释错误，但是，我不知道为什么（GORM 这样做似乎很愚蠢）而且我也不知道如何更改 GORM（Hibernate's ) 行为首先保存父级。

【问题讨论】：

我猜这是因为您的顶级请求使用的是Form form 而不是static hasOne = [form:Form]。
有趣的......修复了它。不认为这是必需的（因为当您想更改哪个表具有外键时，只有一对一关系才需要）。

标签： hibernate grails orm parent-child one-to-many

【解决方案1】：

问题在于您的Request 域类正在为相关的Form 使用简单的属性分配。

因此，您需要使用static hasOne = [form:Form] 而不是Form form 来定义这种关系。

原因是 GORM 通过使用 hasOne 和 hasMany 之类的东西来确定关系，进而可以确定需要插入的东西的顺序。

【讨论】：