Cascade

问题 I have a @ManyToMany (bi-directional) relationship between Item and Category. class Item { @ManyToMany(cascade = CascadeType.ALL) Collection<Category> categories=new ArrayList<Category>(); } class Category { @ManyToMany(mappedBy="categories", cascade = CascadeType.ALL) Collection<Item> items=new ArrayList<Item>(); } I have specified CascadeType.ALL on both. Item is the owner. ManyToMany relationship would be mapped using a third table (Item_Category) When i create an item and add categories

问题 Here is my JPA structure: Movie (look at cascade types): @Entity @Table(name = "movie") public class Movie { @Id @Column(name = "movie_id") @GeneratedValue(strategy = GenerationType.AUTO) private Integer id; //@OneToMany(cascade = CascadeType.ALL, mappedBy = "primaryKey.movie") //stack overflow @OneToMany(mappedBy = "primaryKey.movie") //works fine private List<Rating> ratings; .... } Rating: @Entity @Table(name = "rating") @AssociationOverrides({@AssociationOverride(name = "primaryKey.movie"

问题 I have a one to many relationship between event and session. I'd like cascade to update event fk in session to null when i delete the corresponding event. Any clue how to do this? Thanks and advance. 回答1: Hibernate or JPA unfortunately don't have a Cascade type 'SET to NULL' but you should be able to do it with @PreRemove on the one side (Owner): @OneToMany(mappedBy="whatever") public List<SomeEntity> getSomeEntity(){ return someEntity; } @PreRemove public void onDelete(){ for(SomeEntity se :

问题 I am making a website where users can post 'Posts' and then users can 'Comment' on these posts. I have a database with 3 tables. One contains User Information, one contains Post Information and the final one contains Comment Information. I want to set up rules so that if a User is deleted, all of their posts and comments are deleted, and if the user deletes one of their posts then all of the associated comments are deleted. This however sets up 'Multiple CASCADE paths'. I have been looking

问题 I have problem with deleteing rows in table which has trigger which invokes trigger of second table, which updates row in first table. Here is the description: Table A (id,b_table_count) Table B (id,a_table_id_fk) Table A has trigger BEFORE DELETE which has instructions: BEGIN DELETE FROM b where a_table_fk = OLD.id; RETURN OLD; END; Table B has trigger AFTER DELETE with instruction: UPDATE a SET b_table_count = b_table_count-1 WHERE OLD.a_table_id_fk = a.id; When I delete row from table A,

问题 I've been reading post after post and article after article trying to get cascade deletes to work with JPA/Hibernate in the latest Spring Boot version. I've read that You have to use Hibernate specific cascades and I've read that you don't. I've read that they just don't work but it seems to be a mixed bag. Everything I've tried doesn't work. The relationship is bi-directional. Doesn't Work: @Entity public class Brand { @OneToMany(mappedBy = "brand", orphanRemoval = true, fetch = FetchType

问题 I have been working on a project in C#, a portion of it requires multiple instances of a window to open. Is there any easy way to cascade the instances of the form? I'm assuming I'd have to deal with the math required manually. I just cannot wrap my head around it, any comments or suggestions would be greatly appreciated. 回答1: If I understand you correctly, you want the forms to appear on screen in a cascade effect: If so, when using WinForms you can do this by ensuring that the StartPosition

问题 After merging an entity that has related entities with relations set to cascade both persist and merge operations the relations are lost! Here are the entities: class Event implements NormalizableInterface { /** * @ORM\ManyToMany(targetEntity="Participant", inversedBy="events", cascade={"persist", "merge"}) * @ORM\JoinTable(name="event_participant", * joinColumns={@ORM\JoinColumn(name="event_id", referencedColumnName="id", onDelete="CASCADE")}, * inverseJoinColumns={@ORM\JoinColumn(name=

问题 Projects such as Django-guardian and django-permissions enables you to have object level permissions. However, if two objects are related to each other by a parent-child relationship, is there any way for the child object to inherit permission from the parent object unless otherwise specified? For instance, a subfolder should inherit permission from parent folder unless a user explicitly assigns a different permission for the subfolder. What's the best way to accomplish this using Django, in

问题 I have read many posts on this topic but have not been able to solve it =( I'm trying to save a parent and its children that have a one-to-many relationship. I believe I'm following the documentation and other suggestions from other posts. However, the problem I'm having is that when Hibernate tries to save the child records, it's inserting '0' for the FK to the parent, instead of the real id. The parent hbm.xml mapping <hibernate-mapping> <class name="ParentClass" table="PARENTTABLE"> <id