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POHow to download a file stored in a database with JSF 2.0
 

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    <p>I need to download a file stored in a database. I think i did correctly the query and called it i just dont know how can i connect that to a button in a JSF page. Also i am wondering, do i have to save that image in a folder at the server before passing it to the JSF page. If so, How can i do that?</p> <p>This is the query i use to return the byte[] from the db:</p> <pre><code>@NamedQuery(name = "downloadGarbage", query = "SELECT g.file FROM Garbage g WHERE g.id :idParam") @Entity public class Garbage implements Serializable { @Lob @Column(nullable = false) private byte[] file; .... </code></pre> <p>Here is a simple EJB that calls that query then get the id:</p> <pre><code>@Stateless(name = "ejbs/FileDownloaderEJB") public class FileDownloaderEJB implements IFileDownloaderEJB { @PersistenceContext private EntityManager em; public byte[] downloadGarbage(Long id) { Query query = em.createNamedQuery("downloadGarbage"); query.setParameter("idParam", id); Object o = query.getSingleResult(); byte[] tmpArray = (byte[]) o; return tmpArray; } </code></pre> <p>Now this is the part that confuses me, how can i that above with the JSF page and managed bean?</p> <pre><code>@ManagedBean @RequestScoped public class DownloadController { @EJB private FileDownloaderEJB fileDownloaderEJB; ... private Garbage garbage; public void startDownload(Long id) { fileDownloaderEJB.downloadGarbage(id); //HOW TO START THE DOWNLOAD? //Other Get Set Methods... } } </code></pre> <p>Also how can i pass that long id to the managedBean from the JSF from within a commandButton? Is this allowed?</p> <pre><code>&lt;!-- How to pass the value of id from --&gt; &lt;h:commandButton action="downloadController.startDownload(#{garbage.id})"&gt; </code></pre>
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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.

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