Cascade | 易学教程

Doctrine Cascade Options for OneToMany

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问题 I'm having a hard time making sense of the Doctrine manual's explanation of cascade operations and need someone to help me understand the options in terms of a simple ManyToOne relationship. In my application, I have a table/entity named Article that has a foreign key field referencing the 'id' field in a table/entity named Topic. When I create a new Article, I select the Topic from a dropdown menu. This inserts an integer into the 'topic_id' foreign key field in the Article table. I have the

opencv_traincascade always gets stuck

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问题 I am trying to use OpenCV's opencv_traincascade to generate a Haar Cascade. So far I have 87 distinctive positive samples and 39 negative samples for testing purposes. I generated the .vec file with opencv_createsamples, which worked fine. When I'm running opencv_traincascade it always gets stuck after a few stages, no matter how I change the parameters. My call looks like this: opencv_traincascade -data /opencvimgs/haarcascades/data/ -vec /opencvimgs/haarcascades/out.vec -bg /opencvimgs

Confusion between JPA and Hibernate cascading

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问题 I'm using Hibernate 3.6 and have my code annotated (versus using hibernate mapping files). I ran into the known "problem" of using JPA cascading options that are not compatible with Hibernate's CascadeType (see this link for more info http://www.mkyong.com/hibernate/cascade-jpa-hibernate-annotation-common-mistake/). I was hoping to get a bit more clarification on the problem. I have some particular questions: 1) So @Cascade({CascadeType.SAVE_UPDATE}) works for saveOrUpdate(), but does it

《HTML与CSS知识》系列分享专栏

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NHibernate mapping by code (Loquacious) - Cascade options

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问题 I have a question on Cascade enum options behavior when using NHibernate Mapping By Code. Enum has following options: [Flags] public enum Cascade { None = 0, Persist = 2, Refresh = 4, Merge = 8, Remove = 16, Detach = 32, ReAttach = 64, DeleteOrphans = 128, All = 256, } They are intended to be used like bit flag combinations (as far as I get it). I've looked thru NHibernate documentation, and the following cascade options for XML mappings are defined there: Lifecycles and object graphs Can

Doctrine Cascade Options for OneToMany

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I'm having a hard time making sense of the Doctrine manual's explanation of cascade operations and need someone to help me understand the options in terms of a simple ManyToOne relationship. In my application, I have a table/entity named Article that has a foreign key field referencing the 'id' field in a table/entity named Topic. When I create a new Article, I select the Topic from a dropdown menu. This inserts an integer into the 'topic_id' foreign key field in the Article table. I have the $topic association set up in the Article entity like this: /** * @ManyToOne(targetEntity="Topic") *

JPA Hibernate many-to-many cascading

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I am using JPA 2.0 and hibernate. I have a User class and a Group class as follows: public class User implements Serializable { @Id @Column(name="USER_ID") private String userId; @ManyToMany @JoinTable(name = "USER_GROUP", joinColumns = { @JoinColumn(name = "GROUP_ID") }, inverseJoinColumns = { @JoinColumn(name = "USER_ID") } ) private Set<Group> groupList; //get set methods } public class Group { @Id @Column(name="GROUP_ID") private String groupId; @ManyToMany(mappedBy="groupList") private Set<User> memberList; //get set methods } And then, I create a user and group and then assign the user

MongoDB DBRef ON DELETE CASCADE

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问题 Is there a way in MongoDB to have a foreign key with a 'ON DELETE CASCADE' functionality? I know you can use DBRef as a sort of foreign key but when the item in a collection where the reference points to is removed, the reference returns null. But i want that the item where the reference belongs to gets removed. How do i do this? Or do i need every time i remove things check references to it? 回答1: This feature doesn't exist now. If you want it. Add it on MongoDB Bugtracker http://jira.mongodb

How do I change a child's parent in NHibernate when cascade is delete-all-orphan?

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问题 I have two entities in a bi-directional one-to-many relationship: public class Storage { public IList<Box> Boxes { get; set; } } public class Box { public Storage CurrentStorage { get; set; } } And the mapping: <class name="Storage"> <bag name="Boxes" cascade="all-delete-orphan" inverse="true"> <key column="Storage_Id" /> <one-to-many class="Box" /> </bag> </class> <class name="Box"> <many-to-one name="CurrentStorage" column="Storage_Id" /> </class> A Storage can have many Boxes , but a Box

CASCADE Delete in many-to-many self-reference table

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Table DISPLAY_TAB below is a self-reference table that can contain both parent and child tabs. A parent tab can have multiple child tabs and a child tab can belong to multiple parents. I'd like to establish a CASCADE DELETE relationship between main table and relationship table DISPLAY_TAB_GROUPING so when either parent or child tab is deleted - relationship is automatically deleted as well (just relationship, not actual tab record). So I am creating a FOREIGN KEY constrain on DISPLAY_TAB_GROUPING for fields TAB_ID_R_1 and TAB_ID_R_2 tables, referencing TAB_ID in DISPLAY_TAB table. And it