@QueryHint annotation to customize the query

msi_333 · **Posted:** Wed Apr 21, 2010 5:02 pm

You can use @QueryHint annotation to customize your JPA query ,based on your JPA extension , this annotation parameter will differs. There are two parameter ( name and value ) .

The following code example show you are using "toplink" JPA extension .

Code:

package com.codemiles.jpa;
import java.util.Collection;
import java.util.Date;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.NamedQueries;
import javax.persistence.NamedQuery;
import javax.persistence.Table;
import javax.persistence.OneToMany;
import javax.persistence.QueryHint;


@Entity
@NamedQueries({
    @NamedQuery(name="FinlAllTopics",
                query="SELECT t FROM Topic t"),
@NamedQuery(name="FindTopicByTitle",
            query="SELECT t FROM Topic t WHERE t.title = :title")
            ,
            @NamedQuery(name="FindTopicByTitleAndDate",
                        query="SELECT t FROM Topic t WHERE t.title = :title and t.creationDate=:creationDate",
                        hints={@QueryHint(name="toplink.refresh", value="true")} ) 
                       
}

)
@Table(name="TOPIC")
public class Topic implements java.io.Serializable{
    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    @Id
    private int Id;
    private String title;
    private Date creationDate;
    private Date modifedDate;
    private String content;
    @OneToMany(mappedBy="topic")
    private Collection<Comment> comments;

    public int getId() {
        return Id;
    }
    public void setId(int id) {
        Id = id;
    }
    
    @Column(name="TITLE")
    public String getTitle() {
        return title;
    }
    public void setTitle(String title) {
        this.title = title;
    }
    
    @Column(name="CREATION_DATE")
    public Date getCreationDate() {
        return creationDate;
    }
    public void setCreationDate(Date creationDate) {
        this.creationDate = creationDate;
    }
    
    @Column(name="MODIFED_DATE")
    public Date getModifedDate() {
        return modifedDate;
    }
    public void setModifedDate(Date modifedDate) {
        this.modifedDate = modifedDate;
    }
    
    @Column(name="CONTENT")
    public String getContent() {
        return content;
    }
    public void setContent(String content) {
        this.content = content;
    }
    public void setComments(Collection<Comment> comments) {
    this.comments = comments;
    }
    public Collection<Comment> getComments() {
    return comments;
    }
}
 

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@QueryHint annotation to customize the query

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