JPA @JoinTable具有额外的连接条件 [英] JPA @JoinTable with extra join conditions

问题描述

我花了几个小时在四处搜寻，没有发现类似于我的情况的东西。

让我们假设以下多对多数据模型：

 
合约（任何商业实体）
  -  contract_id 
  - 其他字段
 
合约（另一商业实体）
  -  party_id 
  - 其他字段
 
 Contract_Party（前两个
与附加角色指示符之间的关系，例如拥有者，签名者，卖主等）
  -  contract_id 
  -  party_id 
  - 角色
 

现在让我们假设我想映射所有<与合约有关的合约（单向）。可以在 Party 实体类中使用以下注释完成：

  @ OneToMany 
 @JoinTable（
 name =Contract_Party，
 joinColumns = {@JoinColumn（name =party_id，referencedColumnName =party_id）}，
 inverseJoinColumns = {@ JoinColumn（name =contract_id，referencedColumnName =contract_id）} 
} 
 private List< Contract> contract; 
  

这很好。

但我在寻找的是如何将合约与特定角色

  @OneToMany 
 @ ???（ROLE ='SIGNER'）
 private List< Contract> signedContracts; 
  

技术上，我正在寻找一种方法来添加额外条件

转换为JOIN语句。

到目前为止，在类似主题中发现以下想法：

• 将连接表映射为单独的实体，并使用自定义查询按角色执行筛选;


• Hibernate有@JoinFormula注解，但没办法在@JoinTable中应用它;


• Hibernate也有@Where注解，但它增加了合约表的条件连接表;


• 使用@MapKeyColumn并返回Map而不是List，但每个角色可以有多个合约;
  
• 在数据库上创建一个视图（这个确实有效：）
  
  
  

  谢谢！
  

  解决方案

  您可以使用@WhereJoinTable注解。它适用于关联表
  
  

    @OneToMany 
   @JoinTable（
   name =Contract_Party，
   joinColumns = {@JoinColumn（name =contract_id，referencedColumnName =contract_id）} 
  （name =party_id，referencedColumnName =party_id）}，
   } 
   @WhereJoinTable（ROLE ='SIGNER'）
   private List< Contract>合约; 
    

  
  

  I have spent couple of hours searching around and did not found anything similar to my case.

  Let's assume following many-to-many data model:

  Contract (any business entity)
  - contract_id
  - other fields
  
  Party (another business entity)
  - party_id
  - other fields
  
  Contract_Party (relations between first two 
  with additional role indicator, e.g. owner, signer, seller, etc)
  - contract_id
  - party_id
  - role
  

  Now let's assume I want to map all contracts related to party (uni-directional). It can be done using following annotations in Party entity class:

  @OneToMany
  @JoinTable(
    name="Contract_Party", 
    joinColumns = {@JoinColumn(name="party_id", referencedColumnName="party_id")},
    inverseJoinColumns = {@JoinColumn(name="contract_id", referencedColumnName="contract_id")}
  }
  private List<Contract> contracts;
  

  That is fine.

  But what I'm looking for is how to map contracts with particular role?

  @OneToMany
  @??? ( "ROLE = 'SIGNER' ")
  private List<Contract> signedContracts;
  

  Technically I'm looking for a way to add extra condition into JOIN statement.

  So far found following ideas in similar topics:

  • map join table as separate entity, and perform filtering by role using custom queries;
  • Hibernate has @JoinFormula annotation, but no way to apply it inside @JoinTable;
  • Hibernate also has @Where annotation, but it adds condition for Contract table not for join table;
  • use @MapKeyColumn and return Map instead of List, but I can have multiple contracts per one role;
  • create a view on DB side (this one works indeed :)

  Thanks!

  解决方案

  You can use @WhereJoinTable annotation. It applies to the association table

  @OneToMany
  @JoinTable(
    name="Contract_Party", 
    joinColumns = {@JoinColumn(name="party_id",referencedColumnName="party_id")},
    inverseJoinColumns = {@JoinColumn(name="contract_id", referencedColumnName="contract_id")}
  }
  @WhereJoinTable  ( "ROLE = 'SIGNER' ")
  private List<Contract> contracts;
  

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