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POJPA How to create Query with ManytoOne relationship?
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4763922
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CreationDate
2011-01-21T21:19:59.233
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2011-10-23T00:05:12.803
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2011-01-23T20:56:31.020
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The basic question: If I have an entity B with ManyToOne field x linked to another entity A, how do I get all the instances of B that have A in their x field? More specifically: Consider the following entites: <pre><code>public class User { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "USER_ID") private Key id; @OneToMany(mappedBy = "owner", cascade = CascadeType.ALL) private List<Message> messages; } ic class Message { @Id @GeneratedValue(strategy=GenerationType.IDENTITY) @Column (name="MESSAGE_ID") private Key id; @ManyToOne(fetch = FetchType.LAZY) private User owner; private int status; } </code></pre> I already have this query prepared <pre><code>Query query = em.createQuery("SELECT m from Message m WHERE m.owner = :us"); </code></pre> Here is the api for a method I want to build: Input: User u, Status s Output: List of all message with owner u and status s. I know I am supposed to build a query using EntityMenager but what is the proper syntax? What do I put in the part (*"SELECT m FROM Message m WHERE owner = _ AND status="+status*). when I tried this: <pre><code>Query query = em.createQuery("SELECT m from Message m " +"WHERE m.owner.id = :ownerId"); </code></pre> I got the follwing error: <pre><code>javax.persistence.PersistenceException: SELECT FROM Message m WHERE m.owner.username = :ownerID: Can only reference properties of a sub-object if the sub-object is embedded. </code></pre> Thanks in advance....
Tags
<java><jpa><persistence>
Title
JPA How to create Query with ManytoOne relationship?
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1. USorshachar
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A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.