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POIssue With @OneToMany and Abstraction in JPA
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  1. POIssue With @OneToMany and Abstraction in JPA
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    copied!<p>I have an issue with one-to-many relationship. I have an abstract class Artifact.java. This is not mapped to a table. There are other concrete classes extending from this, and they are mapped to different tables. Now I have another class, mapped to a table, and this class can have a collection of any of these classes, i.e. collection of type Artifact.java. I need to map this using JPA, and have done it as follows.</p> <pre><code>@OneToMany(mappedBy="artifactId",targetEntity=Artifact_Item.class, fetch=FetchType.EAGER, cascade=CascadeType.ALL) private List&lt;Artifact_Item&gt; artifactItemList; </code></pre> <p>This results in the following exception.</p> <pre><code>org.hibernate.AnnotationException: Use of @OneToMany or @ManyToMany targeting an unmapped class: dao.model.Artifact.artifactItemList[dao.model.Artifact_Item] </code></pre> <p>Can anyone please help me solve this issue?</p> <p>Thanks.</p> <p>Alright, I am rephrasing the question. I have a class, Artifact.java, which is mapped to table Artifact. Now each artifact can have multiple sub items (one-to-many), which aren't related in anyway. So, we decided to have an abstract class ArtifactItem.java, so that all the sub items can extend this. Thus, Artifact has List of ArtifactItems.</p> <p>ArtifactItem.java, and is not mapped to table. This contains 2 elements, an id and and artifactId, used as the foreign key. Id has been marked as @GeneratedValue(strategy = GenerationType.AUTO) and artifactId as @ManyToOne(targetEntity = Artifact.class) @JoinColumn(name = "artifact_id", referencedColumnName = "id"). And the class has been annotated as @MappedSuperclass.</p> <p>There are numerous sub-items, extending ArtifactItem. Each has its own table, eg, ArtifactType1.java has its own fields and is mapped to ArtifactType1 table and so on. </p> <p>Now, since Artifact.java's list needs to be mapped to ArtifactItem, as the list is a collection of ArtifactItems. But when I try to map it in the manner mentioned above, I am getting the exception given above.</p> <p>Hope its clearer now :).</p> <p>Thanks. </p>
 

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