使用视图作为与Hibernate的连接表

Question

I've got two entities which I want to join via a common String. I've created a view which I want to use as the join table. This all works fine except for when I try to delete an entity. Hibernate then tries to delete from that view which of course fails. The database used is MySQL.

So I've got

@Entity
public class Event {

   ...
   String productId;
   Date eventDatetime;
   ...
}

@Entity
public class Stock {
   ...
   String productId;
   ...
}

I've created a view in MySQL

DROP VIEW IF EXISTS EVENT_STOCK_VIEW;
create view EVENT_STOCK_VIEW AS
SELECT EVENT.EVENT_ID, STOCK.STOCK_ID 
FROM EVENT, STOCK 
where STOCK.PRODUCT_ID = EVENT.PRODUCT_ID;

in Event I've added:

@ManyToOne(fetch=FetchType.LAZY)
@JoinTable(name="EVENT_STOCK_VIEW",
    joinColumns=@JoinColumn(name="EVENT_ID"),
    inverseJoinColumns=@JoinColumn(name="STOCK_ID",updatable=false,insertable=false))
public Stock getStock(){
    return this.stock;
}

and in Stock:

@OneToMany(fetch=FetchType.LAZY)
    @JoinTable(name="EVENT_STOCK_VIEW",
    joinColumns=@JoinColumn(name="STOCK_ID",updatable=false,insertable=false),       inverseJoinColumns=@JoinColumn(name="EVENT_ID",updatable=false,insertable=false))
    @OrderBy("eventDatetime DESC")
    public List<Event> getEvents(){
        return events;
}

I've googled a bit and found this site . But the solution isn't really that nice (you have to use entity in between stock and event).

Are there any other solutions?

I could use a Hibernate Interceptor and override onPrepareStatement(String sql) and check whether the SQL string contains delete from EVENT_STOCK_VIEW and return an dummy command. Clearly a hack which I try to avoid.

Answer 1

Can't you do it without join table at all? As far as I understand, your relationship is effectively read-only, so that the following approach should work fine:

@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "productId", 
    referencedColumnName = "productId", insertable = false, updateable = false)
public Stock getStock(){
    return this.stock;
}

...

@OneToMany(fetch=FetchType.LAZY, mappedBy = "stock")
@OrderBy("eventDatetime DESC") 
public List<Event> getEvents(){
    return events;
}