Can Foreach and EngineService work together?

[SEAN CHEN <bl...@gmail.com>]

Hi,

Our application needs show a list of image stored in database.  We implemented
a EngineService to stream images in DB to the page, just like the ChartService
did in the Tapestry sample application Workbench.  Separately, it is
working fine.
But here is problem when I put it in a Foreach component.

Briefly our implementation like following:

// service define in .application
<service name="StreamImage" class="com.company.service.StreamImageService"/>

// StreamImageService is similar to ChartService

// StreamImageAsset is similar to Chart

// ImageProvider is similar to IChartProvider have the method to the
image as byte[]
public byte[] getImage();

// html.
<table jwcid="@Foreach" source="ognl:images" value="ognl:eachImage">
 <tr><td>Name:</td>
       <td><span jwcid="@Insert" value="ognl:eachImage.name"/></td>
 </tr>
 <tr><td colspan="2"><span jwcid="@Image" image="ognl:imageContent"/></td>
 </tr>
</table>

// page specification.
 <property-specification name="eachImage" type="com.company.ImageDescriptor"
 />

// page class implements ImageProvider

   public abstract ImageDescriptor getEachImage();

   /**
    * return all images as a List.
    */
   public List getImages() {
        ....
   }

   public byte[] getImage() {

        String name = getEachImage().getName();  /// ---> here causes
problem in Foreach.
        //... get image from database based on the name.
        // stream it to byte[]
   }

   /**
    * the image asset.
    */
   public IAsset getImageContent() {

       return new StreamImageAsset(getPage().getRequestCycle(), this);
   }

But the problem is the return of getEachImage() in method public
byte[] getImage()
of Page class is Null!  I can get each image name as the Insert
Component did,  BUT
I can not get each image for the Image component because we use an
engine service
to create the IAsset?  Why? How to solve it?

Any idea?

Thanks a lot

Sean

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