Graphic Image not showing in Datagrid PrimeFaces

Question

I have problem regarding displaying image in datagrid column. When Datagrid loads it shows the image correctly but whenever I click on second page or refresh the first page, images are gone. I noticed in the console, clicking on second page or refresh the page made the param value null. That's why Image are not showing. I am using sessionscoped. Below is my code:

 public StreamedContent getStreamedImageById() {
FacesContext context = FacesContext.getCurrentInstance();

if (context.getRenderResponse()) {
    // So, we're rendering the view. Return a stub StreamedContent so that it will generate right URL.

    System.out.println("check");
    return new DefaultStreamedContent();
}
else {
    // So, browser is requesting the image. Get ID value from actual request param.
    String firstName = context.getExternalContext().getRequestParameterMap().get("firstName");
    System.out.println("Name:"+firstName);
    System.out.println("Image::"+images.get(firstName));

    return images.get(firstName);

}

In search method I just take all the images in a hash map.

      while(itr.hasNext()){

                com.sysvana.request.UserBean us=itr.next();

            images.put(us.getFirstName(), stringToStreamedContent(us.getJpegPhoto()));
            }

Here is my xhtml::

         <p:graphicImage value="#{userManagementActionBean.streamedImageById}" height="40" width="50" style="align:center"  >

                <f:param id="firstName" name="firstName" value="#{user.firstName}" />
              </p:graphicImage>

Answer 1

This,

return images.get(firstName);

is not right. You should create the streamed content right there and not return one which is already created before in a previous HTTP request. The whole point is that you should not create it in a previous HTTP request, but directly in the very same HTTP request as the getStreamedImageById() method is invoked.

Fix it like follows (assuming that userBean.getJpegPhoto() returns byte[])

UserBean userBean = userService.findByFirstName(firstName);
return new DefaultStreamedContent(new ByteArrayInputStream(userBean.getJpegPhoto())); 

See also:

• Display dynamic image from database with p:graphicImage and StreamedContent
• How to use <p:graphicImage> with DefaultStreamedContent in an ui:repeat?

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Unrelated to the concrete problem, the method name stringToStreamedContent() suggests a major problem. An image is absolutely not to be represented as a String, but as byte[]. When treating an image as a String, you would likely end up in corrupt images due to the information being lost by character encoding issues. You should obtain the image from the DB as byte[] or InputStream.