带有额外连接条件的 JPA @JoinTable [英] JPA @JoinTable with extra join conditions

问题描述

我花了几个小时四处寻找，但没有找到与我的情况类似的东西.

让我们假设遵循多对多数据模型:

<前>合同(任何商业实体)- 合同 ID- 其他领域当事人(另一个商业实体)-party_id- 其他领域Contract_Party(前两者之间的关系带有额外的角色指示器，例如所有者、签名者、卖方等)- 合同 ID-party_id- 角色

现在让我们假设我要映射所有与参与方相关的合同(单向).可以使用 Party 实体类中的以下注释来完成:

@OneToMany@JoinTable(name="Contract_Party",joinColumns = {@JoinColumn(name="party_id",referencedColumnName="party_id")},inverseJoinColumns = {@JoinColumn(name="contract_id",referencedColumnName="contract_id")}}私人名单<合同>合同；

没关系.

但我正在寻找的是如何映射具有特定角色的合同?

@OneToMany@???( "ROLE = 'SIGNER' ")私人名单<合同>签订的合同；

从技术上讲，我正在寻找一种将额外条件添加到 JOIN 语句中的方法.

到目前为止，在类似主题中发现了以下想法:

• 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过滤；
• Hibernate 有@JoinFormula 注释，但无法在@JoinTable 中应用它；
• Hibernate 也有@Where 注释，但它为合同表而不是连接表添加了条件；
• 使用@MapKeyColumn 并返回 Map 而不是 List，但我可以为一个角色拥有多个合同；
• 在数据库端创建一个视图(这个确实有效:)

谢谢！

解决方案

可以使用@WhereJoinTable 注解.适用于关联表

@OneToMany@JoinTable(name="Contract_Party",joinColumns = {@JoinColumn(name="party_id",referencedColumnName="party_id")},inverseJoinColumns = {@JoinColumn(name="contract_id",referencedColumnName="contract_id")}}@WhereJoinTable ("ROLE = 'SIGNER'")私人名单<合同>合同；

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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