one-to-one

来源： https://stackoverflow.com/questions/58561156/post-upgrade-mapsid-is-throwing-an-error-when-saving-an-existing-entity-but-o

来源： https://stackoverflow.com/questions/27804010/how-to-serialize-a-relation-onetoone-in-django-with-rest-framework

来源： https://stackoverflow.com/questions/27804010/how-to-serialize-a-relation-onetoone-in-django-with-rest-framework

问题 I have set up a 1-to-1 relationship using EF code first following the method prescribed here: Unidirectional One-To-One relationship in Entity Framework My mapping looks like this ... protected override void OnModelCreating(DbModelBuilder modelBuilder) { modelBuilder.Entity<Asset>() .HasRequired(i => i.NewsItem) .WithOptional(e => e.Asset) .Map(m => m.MapKey("NewsItemId")); } But when I get this exception ... A relationship from the 'Asset_NewsItem' AssociationSet is in the 'Deleted' state.

问题 Considering the following "model": USER Long: PK String: firstName String: lastName USER_EXT Long: PK String: moreInfo Date: lastModified I'm trying to find/create the correct Hibernate mapping (using Annotations) such that, with an HQL query as simple as "from User", it would generate the following SQL: select firstName, moreInfo from USER, USER_EXT where user.pk = user_ext.pk I've tried everything, from using @Secondarytable to @OneToOne association, but I can't make it work. The best

问题 Considering the following "model": USER Long: PK String: firstName String: lastName USER_EXT Long: PK String: moreInfo Date: lastModified I'm trying to find/create the correct Hibernate mapping (using Annotations) such that, with an HQL query as simple as "from User", it would generate the following SQL: select firstName, moreInfo from USER, USER_EXT where user.pk = user_ext.pk I've tried everything, from using @Secondarytable to @OneToOne association, but I can't make it work. The best

问题 I'm trying to learn Go and Gorm by building a little prototype order management app. The database is MySQL. With simple queries Gorm has been stellar. However, when trying to obtain a result set involving a combination one-to-many with a has-one relationship Gorm seems to fall short. No doubt, it is my lack of understanding that is actually falling short. I can't seem to find any online examples of what I am trying to accomplish. Any help would be greatly appreciated. Go Structs // Order type

问题 I'm trying to achieve to have an entity called MyEntity along with another entity called MyEntityInfo using Hibernate 5.3.13.Final with annotations under Wildfly 18. The idea is to have MyEntity store some commonly requested fields, and MyEntityInfo store some rarely requested fields. Both share the same primary key called SID (Long), and there is a FK from Info's SID to Entity's SID. There can be entities without info. Normally you will not require the additional info. For example, I don't

问题 I want a unidirectional one-to-one relationship between objects of 3 java classes: Person to Heart, and Person to Liver. I want the objects to share the same PK i.e. every person has a corresponding heart and liver, where person.person_id = heart.heart_id = liver.liver_id. I do not want to merge the 3 tables into 1 because each has loads of fields. Here's my code (mostly based on the accepted answer for this question): @Entity public class Person { public long personId; private String name;

问题 How do I get the following relationship to only generate the FK in Entity2? public class Entity1 { public int Id { get; set; } public virtual Entity2 Entity2 { get; set; } } public class Entity2 { public int Id { get; set; } public int? Entity1Id { get; set; } public virtual Entity1 Entity1 { get; set; } } I want Entity1 be able to get a reference to an Entity2 (have EF lazy load it), but I don't want Entity1 to have an FK to Entity2 in the db, I just want Entity2 to have an FK to Entity1. Is