apart from asking the database _again_ for the data or presence thereof
Whether the image is visible must be determined when the page is rendered. The
actual loading of the image is done in another request. Thus two times to ask
the databse.
Alternatively you may render a default resource (e.g.
https://www.google.com/search?q=no+image) if your database doesn't have any
data to stream back when the image is requested.
Regards
Sven
On 07/16/2013 10:53 PM, Stefan Renz wrote:
Hi guys,
I'm desparate for your help: I just can't figure out how to suppress an
Image in case its IResource yields nothing.
Here's some context:
A customer may have a custom logo image (in fact, there's some logic
involved in determining which exact logo to use, but that's beside the
point) located in some database. Using Wicket's Image component, I
figured I would need to implement the logo resolution algorithm and
loading from the DB with either subclassing DynamicImageResource, or
subclassing AbstractResourceStream (which is more approriate?).
Works fine if a logo is there -- the image shows up. However, if there
_is_ no logo, the browser (firefox in my case) renders a question mark
instead of showing nothing. Both returning null or an empty byte array
doesn't matter.
I usually suppress a component with a behavior, or within the
#onConfigure()-Method, but in the Image's case, where I only have an
IResource or ResourceReference, I just don't have a hint on how to
determine if the image data is there or not (apart from asking the
database _again_ for the data or presence thereof).
Any ideas? What method/class have I missed? Where should I look?
Thanks for your help.
Cheers
Stefan
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