java - How to merge a @OneToMany relationship effectively? -

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For example, I have the following two unit squares with one-to-many relationship: 

  Public Class A implementation serializable {... @OnTomain (mapped = "A", cascade = cascade type.AL) Private list & lt; B & gt; Bs; ...} public class B serializable {... @ManyToOne applies a private A; ...}   
 Suppose i have an example of  a  to  a , and  a.bs == [B1, b2, b3] . Now I want to remove the relationship from  b1 , and add  b4  so that  a.bs == [b2, b3, b4] , and  b1.a == blank .  
 I tried to do  a.setBs (b2) after em.merge (a) , b3, b4) , But the result will be  a.bs == [b1, b2, b3, b4] , unless I do not specify  b1.setA (null) . However, if there is a complexity then a lot changes in  a.bs , and if there are multiple relationships for the other unit sections in  A   orphanRemoval The = true  setting is also not a solution, because I just want to set  b1.a = null  instead of  b1 .  
 
 "post-text" itemprop = "text"  
 
   
  P> You can set the waterfall style to update on  BS  and  a.bs.remove (b1); Session.update (a);   
 This trick does.  
 When you are asking ORM to update the cascade on the archive, the related value will be canceled when you archive.

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