[ZPT] tal:condition question for TALES

[robert rottermann]

Hi Kim,
your problem is easy solveable.
Just ask for the size of the pdf, and then base your condition on that.

tal:define="size
string:/information/${product/pid}.pdf/getSize | 0;

HTH
robert



Kim Groves wrote:
>Hi,
>
>Is it possible to use the existence of a file on the webserver as a
>condition in a TALES expression?
>
>I have read many pages on Zope/TAL/TALES and they seem to indicate that it
>is, however none of the offered syntaxes seem to operate correctly.
>
>Here is the scenario:
>
>We have a directory on the webserver: /information
>which contains a set of pdf documents. The application is a cart, eg
>webshop.
>The products on the site may or may not have an associated pdf file. The
>name of the pdf is the same as the Product Id.
>eg:
>  <tr><td colspan=4><a target="" href="" tal:define="pdf_path
>string:/information/${product/pid}.pdf"
>tal:condition="exists:pdf_path" tal:attributes="href pdf_path; target
>pdf_path">Information Sheet</a></td></tr>
>
>If the pdf file does exist, then the link will take the visitor to the file,
>so that bit works okay.
>However, if the pdf does not exist, we are still getting a link on the page,
>and this link opens a new window with an error message from the server, eg
>"Requested URL not found.
>
>The requested URL "www.domain.com/information/75080.pdf" was not found in
>this shop.
>
>You can return to the shop front by clicking here"
>
>I asked one of the people at the company that operates the web site for
>ideas, they suggested defining a property on each product with the pdf href
>(if available), however there are hundreds of pdf files so this would not be
>feasible/fun. We have an inhouse server with a different site using php and
>it is able to test for the existence of the file before showing the link on
>the returned page.
>
>Can anybody provide a concrete example of the correct syntax for checking
>for a path using TALES?
>
>Is it possible the server we are using has been customised/modified so that
>the expressions do not behave as you would normally expect?
>
>I have also tried tal:condition:"path:root/information/${product/pid}.pdf"
>but this either generates an error page or always returns true, whether the
>file exists or not.
>
>Thanks
>
>Kim Groves
>
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