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Hello i have got one entity which contains collection of object:

@Entity
public class ResourceType{
   @Id
   public Integer id;

  @ManyToMany(mappedBy = "resourcesTypes")
  private Set<Resource> resources = new HashSet<>();

}

As you see this entity contains collection of Resource

@Entity
public class Resource{

    @OneToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
    @JoinTable(name = "RESOURCE_TYPE_CROSS", joinColumns = { @JoinColumn(name = "RESOURCE_ID") }, inverseJoinColumns = { @JoinColumn(name = "RESOURCE_TYPE_ID", referencedColumnName = "ID") })
    private List<ResourceType> resourcesTypes = new ArrayList<>();
}

So i guess if i get all resourceTypes with all resources this collection is in local cache.

But if i try persist resource : 

    @Override
    public ResourcesDTO createResource(ResourcesDTO resource) throws CreateResourceException {

    if (resource.getResourcesTypes().isEmpty()) {
        throw new CreateResourceException("Can not create resouce " + resource.getName()
                + " none resource types is set");                                      
    resourceDAO.create(map(resource));      

    log.debug("Created resource: " + r);
    resource.setId(r.getId());

    return resource

    }

If i perssist Resource with ResourcesTypes and next i will get all ResourceTypes entity manager do not found new Resources. But in my cross table resource_type_cross everything is ok. i will try to do something like that after create new resource:

for(ResourceType rt : resource.getResourceTypes()){
    em.refresh(rt);
}

But its not working properly. After i will restart server everything is fine. But why entity manager do not refresh resource type ??

This is what i use to read all ResourceTypes: 

public ResourceType getAllResourceTypes(){
    em.createQuery("Select n from Resource n left join fetch n.children"); 
    return em.find(ResourceType.class, 0); //0 - ROOT

}

as follow article : http://www.tikalk.com/java/load-tree-jpa-and-hibernate

The Main question is that : create or update entity by one side do not update another, so in my case i create and update resource type by resource entity, but i am using resouce type to get all resource.

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1 に答える 1

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まず、ManyToMany マッピングに問題があります。双方向ではなく、同じ結合テーブルにアクセスする両側を一方向にしました。一方がマッピングを制御し、もう一方が所有側によってマップされるように設定する必要があります。

次に、ResourceTypes を更新するときに、変更をフラッシュまたはコミットしましたか? クエリを実行してすべての ResourceType を更新するのではなく、コードで参照を設定して両方を維持することをお勧めします。

于 2013-06-12T12:20:56.523 に答える