休眠异常：org.hibernate.AnnotationException：没有为实体指定标识符：com..domain.idea.MAE_MFEView [英] hibernate exception: org.hibernate.AnnotationException: No identifier specified for entity: com..domain.idea.MAE_MFEView

问题描述

  package com.domain.idea; 
 
 import javax.persistence.CascadeType; 
 import javax.persistence.Entity; 
 import javax.persistence.FetchType; 
 import javax.persistence.JoinColumn; 
 import javax.persistence.OneToOne; 
 import javax.persistence.Table; 
 
 import org.hibernate.annotations.AccessType; 
 $ b / ** 
 *视图[投资返回] vMAE_MFE，schema =InvestmentReturn）
 @AccessType（field）
 public class MAE_MFEView 
 {
 / ** 
 * trade属性是SuggestdTradeRecommendation对象
 * / 
 @OneToOne（fetch = FetchType.LAZY，cascade = {CascadeType.PERSIST}）
 @JoinColumn（name =suggestedTradeRecommendationID）
 private SuggestedTradeRecommendation trade; 
 
 / ** 
 *绝对值偏移值
 * / 
 private int MAE; 
 
 public int getMAE（）
 {
 return MAE; 
} 
 
 / ** 
 *最优惠的游览价值
 * / 
 private int MFE; 
 
 public int getMFE（）
 {
 return MFE; 
} 
 
 / ** 
 * @return交易产权
 *参见#trade 
 * / 
 public SuggestedTradeRecommendation getTrade（）
 {
回报交易; 
 
 
  

更新：我将代码更改为这：

  package com.domain.idea; 
 
 import javax.persistence.CascadeType; 
 import javax.persistence.FetchType; 
 import javax.persistence.Entity; 
 import javax.persistence.Id; 
 import javax.persistence.JoinColumn; 
 import javax.persistence.OneToOne; 
 import javax.persistence.Table; 
 
 import org.hibernate.annotations.AccessType; 
 $ b / ** 
 *视图[投资返回] vMAE_MFE，schema =InvestmentReturn）
 @AccessType（field）
 public class MAE_MFEView 
 {
 / ** 
 * trade属性是SuggestdTradeRecommendation对象
 * / 
 @Id 
 @OneToOne（fetch = FetchType.LAZY，cascade = {CascadeType.PERSIST}）
 @JoinColumn（name =suggestedTradeRecommendationID）
私人建议交易推荐交易; 
 
 / ** 
 *绝对值偏移值
 * / 
 private int MAE; 
 
 public int getMAE（）
 {
 return MAE; 
} 
 
 / ** 
 *最优惠的游览价值
 * / 
 private int MFE; 
 
 public int getMFE（）
 {
 return MFE; 
} 
 
 / ** 
 * @return交易产权
 *参见#trade 
 * / 
 public SuggestedTradeRecommendation getTrade（）
 {
回报交易; 
 
 
 $ / code $ / pre 
 
 
但现在我得到这个异常： p> 
 
 
 原因：org.hibernate.MappingException：无法确定com.domain.idea.SuggestedTradeRecommendation的类型，其表格为：vMAE_MFE，对于列：[org.hibernate.mapping.Column（trade）] 
 at org.hibernate.mapping.SimpleValue.getType（SimpleValue.java:292）
 at org.hibernate.mapping.SimpleValue.isValid （SimpleValue.java:276）
 at org.hibernate.mapping.RootClass.validate（RootClass.java:216）
 at org.hibernate.cfg.Configuration.validate（Configuration.java:1135）
 at org.hibernate.cfg.Configuration.buildSessionFactory（Configuration.java:1320）
 at org.hibernate.cfg.AnnotationConfiguration.buildSessionFactory（AnnotationConfiguration.java:867）
 at org.hibernate。 ejb.Ejb3Configuration.buildEntityManagerFactory（Ejb3Configuration.java:669）
 ... 145 more 
  
 
 
解决方案
您错过了使用 @Id 注释的字段。每个 @Entity 需要一个 @Id   - 这是数据库中的主键。  
 
 
如果您不希望您的实体被保存在单独的表中，而是成为其他实体的一部分，则可以使用 @可嵌入的代替 @Entity 。
 
 
 
如果您只需要一个数据传输对象更新：关于SQL视图，Hibernate文档写道：
更新：关于SQL视图，Hibernate文档编写如下：
 p> 
 
 
 
 
 Hibernate映射的视图和基表之间没有区别。这在数据库级别是透明的。
 
 
 
Why am I getting this exception?
package com.domain.idea;

import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.JoinColumn;
import javax.persistence.OneToOne;
import javax.persistence.Table;

import org.hibernate.annotations.AccessType;

/**
 * object model for the view [InvestmentReturn].[vMAE_MFE]
 */
@Entity
@Table(name="vMAE_MFE", schema="InvestmentReturn")
@AccessType("field")
public class MAE_MFEView
{
    /**
     * trade property is a SuggestdTradeRecommendation object
     */
    @OneToOne(fetch = FetchType.LAZY , cascade = { CascadeType.PERSIST })
    @JoinColumn(name = "suggestedTradeRecommendationID")
    private SuggestedTradeRecommendation trade;

    /**
     * Most Adeverse Excursion value
     */
    private int MAE;

    public int getMAE()
    {
        return MAE;
    }

    /**
     * Most Favorable Excursion value
     */
    private int MFE;

    public int getMFE()
    {
        return MFE;
    }

    /**
     * @return trade property
     * see #trade
     */
    public SuggestedTradeRecommendation getTrade()
    {
        return trade;
    }
}
Update: I've changed my code to look like this:  
package com.domain.idea;

import javax.persistence.CascadeType;
import javax.persistence.FetchType;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToOne;
import javax.persistence.Table;

import org.hibernate.annotations.AccessType;

/**
 * object model for the view [InvestmentReturn].[vMAE_MFE]
 */
@Entity
@Table(name="vMAE_MFE", schema="InvestmentReturn")
@AccessType("field")
public class MAE_MFEView
{
    /**
     * trade property is a SuggestdTradeRecommendation object
     */
    @Id
    @OneToOne(fetch = FetchType.LAZY , cascade = { CascadeType.PERSIST })
    @JoinColumn(name = "suggestedTradeRecommendationID")
    private SuggestedTradeRecommendation trade;

    /**
     * Most Adeverse Excursion value
     */
    private int MAE;

    public int getMAE()
    {
        return MAE;
    }

    /**
     * Most Favorable Excursion value
     */
    private int MFE;

    public int getMFE()
    {
        return MFE;
    }

    /**
     * @return trade property
     * see #trade
     */
    public SuggestedTradeRecommendation getTrade()
    {
        return trade;
    }
}
but now I'm getting this exception:  
Caused by: org.hibernate.MappingException: Could not determine type for: com.domain.idea.SuggestedTradeRecommendation, at table: vMAE_MFE, for columns: [org.hibernate.mapping.Column(trade)]
    at org.hibernate.mapping.SimpleValue.getType(SimpleValue.java:292)
    at org.hibernate.mapping.SimpleValue.isValid(SimpleValue.java:276)
    at org.hibernate.mapping.RootClass.validate(RootClass.java:216)
    at org.hibernate.cfg.Configuration.validate(Configuration.java:1135)
    at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1320)
    at org.hibernate.cfg.AnnotationConfiguration.buildSessionFactory(AnnotationConfiguration.java:867)
    at org.hibernate.ejb.Ejb3Configuration.buildEntityManagerFactory(Ejb3Configuration.java:669)
    ... 145 more

解决方案
You are missing a field annotated with @Id. Each @Entity needs an @Id - this is the primary key in the database. 

If you don't want your entity to be persisted in a separate table, but rather be a part of other entities, you can use @Embeddable instead of @Entity.

If you want simply a data transfer object to hold some data from the hibernate entity, use no annotations on it whatsoever - leave it a simple pojo.

Update: In regards to SQL views, Hibernate docs write:

  
There is no difference between a view and a base table for a Hibernate mapping. This is transparent at the database level


                        
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