Question

我有一个存储代理层次结构的表：

create table agent (
  agent_id int not null,
  agent_name varchar(255),
  agent_parent_id,
  constraint pk_agent primary key (agent_id));

alter table agent 
  add constraint fk_agent_agent foreign key (agent_parent_id) references (agent_id);

我把它建模为：

class Agent {
  String agentName
  Agent agentParent
  static mapping = {
    id column: 'agent_id'
    id generator: 'sequence', params: [sequence: 'agent_id_seq']
  }
}

每个代理可能有许多属性：

create table agent_property (
  agent_property_id int not null,
  agent_property_name varchar(255),
  agent_id int,
  constraint pk_agent_property primary key (agent_property_id));

alter table agent_property (
  add constraint fk_agent_property_agent foreign key (agent_id) references agent(agent_id);

我将其建模为：

class AgentProperty {
  String agentPropertyName
  static hasOne = [agent: Agent]
  static mapping = {
    id column: 'agent_property_id'
    id generator: 'sequence', params: [sequence: 'agent_property_id_seq']
  }
}

我已经创建了一个视图，可以轻松查看代理的层次结构：

create view pathogen as
  select c.agent_id as id, a.agent_name as genus, b.agent_name as species, c.agent_name as strain, d.agent_name as toxin
  from agent a 
  left join agent b on a.agent_id = b.agent_parent_id
  left join agent c on b.agent_id = c.agent_parent_id
  left join agent d on c.agent_id = d.agent_parent_id
  where a.agent_parent_id is null;

我的问题在于对病原体视图进行建模。我做到了这一点：

class Pathogen {
  String genus
  String species
  String strain
  String toxin
  static hasMany = [agentProperties: AgentProperty]
}

这意味着agent_property表中有一个外键'pathogen_id'。但事实并非如此。外键是agent_id。我希望AgentProperty与agent_id上的Pathogen相关联，就好像存在约束：

alter table agent_propery 
  add constraint fk_agent_property_pathogen foreign key (agent_id) references pathogen (id);

我尝试将隐含的属性agentProperties映射到我的Pathgeon类中的agent_id，如：

static mapping = {
  agentProperties column: agent_id  // or AgentProperty.agent
}

但这不起作用。

如何告诉GORM使用agent_property.agent_id作为外键？

Answer 1

我原来问题的解决方案是我没有将agent_id放在引号中。

agentProperties column: 'agent_id'

现在可以使用：

class Pathogen {
  String genus
  String species
  String strain
  String toxin

  static hasMany = [agentProperties: AgentProperty]

  static mapping = {
    // use agent_id to releate to AgentProperty
    agentProperties column: 'agent_id'
  }
}

class AgentProperty {
  String agentPropertyName

  static belongsTo = [agent: Agent]
  static hasOne = [pathogen: Pathogen]

  static mapping = {
    id column: 'agent_property_id'
    id generator: 'sequence', params: [sequence: 'agent_property_id_seq']
    // use agent_id to relate to Pathogen
    pathogen column: 'agent_id', insertable: false, updateable: false
  }
}

Answer 2

您的域类需要进行一些修改才能坚持数据库中的设计，

class Agent {
  String agentName
  Agent agentParent

  //agent_id Foreign Key to AgentProperty. Agent has many AgentProperties
  static hasMany = [agentProperties: AgentProperty] 

  static mapping = {
    id column: 'agent_id'
    id generator: 'sequence', params: [sequence: 'agent_id_seq']
  }
}

class AgentProperty {
  String agentPropertyName

  //AgentProperty belongs to an Agent. Cascade delete is enabled
  static belongsTo = [agent: Agent]
  static mapping = {
    id column: 'agent_property_id'
    id generator: 'sequence', params: [sequence: 'agent_property_id_seq']
  }
}

class Pathogen {
  String genus
  String species
  String strain
  String toxin

  //like foreign key pathogen_id in agent table
  static hasMany = [agents: Agent]
}

您可以AgentProperty通过Pathogen抓住Agent。

如果我正确地阅读了您的问题，那么这就是您所需要的。

Pathogen hasMany Agents
Agent hasMany AgentProperty

Grails / GORM映射到非标准外键

2 个答案: