12/16/2023 0 Comments Manytoone spring= GenerationType.IDENTITY) annotation sets the id field to be autogenerated and GenerationType.IDENTITY marks the field as unique.annotation marks the id field as the primary for the database table that will be generated from the Recipe entity.annotation marks the Recipe data class as a JPA entity that can be persisted into the database.Import data class = GenerationType.IDENTITY) //Uses underlying persistence framework to generate an Id In the Recipe.kt file we created earlier, add the code snippets below. From our entity relationship diagram above we can see that the Recipe entity has a OneToMany relationship with the ingredient entity meaning that a single recipe is capable of having several ingredients. In this type of JPA relation, a row in the parent entity is referenced by many child records in another entity. ALL - applies all the above cascade options.DETACH - detaches all the related entities if a manual detach occurs.REMOVE - removes all the related entities whenever the owning entity is deleted.REFRESH - related entities are refreshed when the owning entity is refreshed.MERGE - related entities are merged if the owning entity is merged.PERSIST - save operations are cascaded to related entities.JPA CASCADE types control how state changes are cascaded from the parent object to child objects. This type of mapping is recommended since it makes it possible to navigate the object graph in both directions. If entity A has a one-to-many relation with entity B then a one-to-many annotation is used on entity A and a Many-To-One annotation is used on entity B. Bidirectional mapping - This is where the JPA mappings are declared on both entities that are related.If entity A has a one-to-many relationship with entity B then only a one-to-many relationship annotation is on entity A. Unidirectional mapping - This is where the JPA mapping is only done on one side of the relationship.In the domain package you created above, create two Kotlin files with the names Recipe.kt and Ingredient.kt.In the root package where the DemoApplication.kt file exists, create a new package with the name domain.The domain package is where we will define our models. Sync the project with maven to download and all the dependencies. I will be using Intelij IDEA community which is available for free.
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