User.java UserRole.java RolePermission.java JDK:17 SpringBoot:2.7.4 findById and findBy are also generate different structure SQL. findById uses left outer Join. findByName uses subquery. the user only have one role, the role have three permissions. if use findByUsername It will return the user info correctly…
Tag: many-to-many
Many to many relationship doesn’t add new Entity into the table
I have two entities Book and BookTag. They are connect by many to many relationship. I try to add to the set of bookTags new BookTag entity using such service method But it doesn’t work, after I saved an entity into the mysql database it work correctly view of books_tags table after inserting a new tag …
Hibernate simply adding elements to manytomany from JSON
I want to add elements in my manytomany association via a request without loading each added element. I am using a custom join table. [Code will be added at the bottom] So for example this is the JSON I get: So there is one HomeworkMaterial. If I send this as POST to the server nothing happens (as expected). …
JPA ManToMany association and insert, retrieve data with Spring Data Repository
I need to setup many to many relationship between 2 entities, namely Project and Articles. The use case is a project that can be linked to many articles which are related. So does each article will be linked to various projects. I am using Spring data repository in my project and having trouble persisting and…
Joint table in many-to-many is not updating
I have a relation N:M between 2 entities, “Alumno” and “Curso”: Alumno Curso On AlumnoService I have the following two methods: According to the printed lines, all the data is fetch correctly, and on Postman I get a correct answer: This is the AlumnoController: However, upon inspecting…
spring-data-jpa many to many findByID
i have many to many relationship between book and author, i have 3 tables: author, book and author_book. i can add data to db without a problem, but when i want to get an author or a book by its id i get an error: LazyInitialization failed to lazily … I want to use FetchType.LAZY and get the instance of
How to remove child objects from a @ManyToMany relation with lots of children in JPA and Hibernate
Let’s say I have two entities: Organization and User. Every user can be a member of many organizations and every organization can have many users. Now, I want to remove an organization (let’s say it has 1000 members). When the user has few organizations, this code is ok: But when organization coun…
Which collections are supported by Hibernate @ManyToMany annotation
I used @ManyToMany annotation on a Set and it worked fine. When I used ArrayList instead of Set it throws exception: org.hibernate.AnnotationException: Illegal attempt to map a non collection as a @OneToMany, @ManyToMany or @CollectionOfElements: com.kaushik.winnersoft.data.Student.enrolledCourses Is ArrayLis…
JOOQ pojos with one-to-many and many-to-many relations
I am struggling to understand how to handle pojos with one-to-many and many-to-many relationships with JOOQ. I store locations that are created by players (one-to-many relation). A location can hold multiple additional players who may visit it (many-to-many). The database layout comes down to the following: W…
Many to many with Hibernate and annotations for self referencing
My brain is starting to hurt thinking about this, is it as simple as: Answer Something like: