I am building a web application using Click on the Google App Engine. One of
the 'features' I would like to have is the ability to try setting a template --
if it is available. Like the Click example we have a BasePage > BorderPage
(with a template of border.htm) and our Page classes extend BorderPage.
One of those Page classes is BrandPage -- for some consumer brands. The
BrandPage will have some common methods - search for products matching this
brand for example - think ecommerce. Additionally, there is a brand.htm file
for the BrandPage.
However, I would like some brands, not all, to have a template available to
parse - we would like to build out some custom .htm pages to parse in the
brand.htm. For example we may have three brands , A, B, C and A.htm, C.htm but
not a B.htm in a directory say ... /brand/A.htm
Normally in the BrandPage I would put something like this:
public String getTemplate()
{
return A.htm (or C.htm, or even B.htm)
}
From the example above, while A.htm or C.htm exist, B.htm does not.
How this would have happened is that when the BrandPage was requested, with a
brand id for example, the database search would return the brand (and product
etc...). I would then 'dynamically' set the getTemplate() return to [Normalized
Brand Name].htm
My question is this -- how can I test to see if B.htm exists before I even set
the getTemplate return value? My focus has been using something utility-wise in
Click - am I missing a simple way to do this? Wrap a try catch somewhere? As
you would expect, I currently get the
org.apache.velocity.exception.ResourceNotFoundException -- but I cannot catch
it in the Page in order to do something else.
I also want it to be a quick process. I have pondered using File to look in a
specific directory ("/brand/file.htm"). My biggest concerns are: 1. Speed for
this 'function', 2. Google App Engine restrictions - would looking at a file in
the /war cause an issue, and finally if Click has something I missed as a
convenience for this idea. Solving this gives us tremendous flexibility on the
presentation and is a critical feature to our application. I am also concerned
that the way I am thinking about this is flawed so any alternative design
pattern suggestions are welcome.
Thank you for a great framework - I have tried nearly all of them and Click
nailed it.
