休眠：@UniqueConstraint与@ManyToOne领域？ [英] Hibernate: @UniqueConstraint with @ManyToOne field?

问题描述

使用以下代码：

  @Entity 
 @Table（uniqueConstraints = [@ UniqueConstraint（columnNames = [ account，name]）]）
 class Friend {
 @Id @GeneratedValue（strategy = GenerationType.AUTO）
 public Long id 
 @ManyToOne 
公共账户账户
 public String href 
 public String name 
} 
  

我得到以下错误：

pre $ org.hibernate.AnnotationException：无法在表上创建唯一的键约束（帐户，名称）朋友：找不到帐户


看起来这与@ManyToOne约束有关，我认为它实际上是创建一个单独的UniqueConstraint ???

在任何情况下，如果我拿出来，没有关于UniqueConstraint的抱怨，但是还有另一个错误让我相信它必须留在。

  org.hibernate.MappingException：无法确定com.mksoft.fbautoma的类型te.domain.Account，at table：Friend，for columns：[org.hibernate.mapping.Column（account）] 
  

任何提示我如何创建这样一个所需的约束（即，每个帐户和名称的组合只出现一次???）

谢谢！

解决方案

解决方案：
$ b

  @Entity 
 @Table（uniqueConstraints = [@ UniqueConstraint（columnNames = [myaccountcolum，name]）] 
 class Friend {
 @Id @GeneratedValue（strategy = GenerationType.AUTO）
 public Long id 
 @ManyToOne 
 @JoinColumn（name =myaccountcolum）
 public帐户帐户
 public String href 
 public String name 
} 
  

说明：
生成表中@ManyToOne的列名称可能与account_id而不是帐户类似。 @UniqueConstraint需要确切的列名称，而不是您在类中使用的名称。为了确保它正常工作，请使用@JoinColumn为此列指定一个特定名称，并确保您的UniqueConstraint中使用了相同的名称。

Using the following code:

@Entity 
@Table(uniqueConstraints=[@UniqueConstraint(columnNames=["account","name"])])
class Friend {
  @Id @GeneratedValue(strategy=GenerationType.AUTO)
  public Long id
  @ManyToOne
  public Account account
  public String href
  public String name
}

I get the following error:

org.hibernate.AnnotationException: Unable to create unique key constraint (account, name) on table Friend: account not found

It seems this has to do with the @ManyToOne constraint, which I imagine actually creates a separate UniqueConstraint???

In any case, if I take this out, there is no complaint about the UniqueConstraint, but there is another error which makes me believe it must be left in.

org.hibernate.MappingException: Could not determine type for: com.mksoft.fbautomate.domain.Account, at table: Friend, for columns: [org.hibernate.mapping.Column(account)]

Any hints how I can create such a desired constraint (i.e., that each combination of account and name occurs only once???)

Thank you!

Misha

解决方案

The solution:

@Entity 
@Table(uniqueConstraints=[@UniqueConstraint(columnNames=["myaccountcolum","name"])])
class Friend {
  @Id @GeneratedValue(strategy=GenerationType.AUTO)
  public Long id
  @ManyToOne
  @JoinColumn(name="myaccountcolum")
  public Account account
  public String href
  public String name
}

Explanation: The column name for the @ManyToOne in the generated table will probably be something like account_id instead of account. The @UniqueConstraint expects the exact column name, not the name you use in your class. To make sure it just works, give this column a specific name with @JoinColumn and make sure the same name is used in your UniqueConstraint.

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