How are the product HTML pages generated?

When a user clicks on a product from a category listing, what files generate the result for the user?

The product info comes from the database rather than a file, also the files are php and not html. What is it you are wanting to do/know?

And the product info is build-up through multiple php-files, so like picandnix said. We need a little more information

When I click on a category from the category sidebox, a blank page loads instead of the products in that category.

Blank as in completely empty, or as in center column empty? You likely have a PHP error; see the tutorials or the wiki under "troubleshooting". Also look in your /cache/ folder in your Zen Cart root and post the latest myDebug file.

Center column empty.

myDEBUG-1348339549-197239.log:

[22-Sep-2012 12:45:49] PHP Warning: include_once(includes/languages/english.php) [<a href='function.include-once'>function.include-once</a>]: failed to open stream: No such file or directory in /home/pnaples9/public_html/spa/includes/init_includes/init_templates.php on line 72
[22-Sep-2012 12:45:49] PHP Warning: include_once() [<a href='function.include'>function.include</a>]: Failed opening 'includes/languages/english.php' for inclusion (include_path='.:/usr/lib/php:/usr/local/lib/php') in /home/pnaples9/public_html/spa/includes/init_includes/init_templates.php on line 72

capncrunch0:

[22-Sep-2012 12:45:49] PHP Warning: include_once(includes/languages/english.php) [function.include-once]: failed to open stream: No such file or directory in ...

The error message is telling you that your english.php file is missing.

Thank you.

The latest debug file when I tested the problem:

[22-Sep-2012 22:30:34] PHP Warning: include_once(includes/languages/english.php) [<a href='function.include-once'>function.include-once</a>]: failed to open stream: No such file or directory in /home/pnaples9/public_html/spa/includes/init_includes/init_templates.php on line 72
[22-Sep-2012 22:30:34] PHP Warning: include_once() [<a href='function.include'>function.include</a>]: Failed opening 'includes/languages/english.php' for inclusion (include_path='.:/usr/lib/php:/usr/local/lib/php') in /home/pnaples9/public_html/spa/includes/init_includes/init_templates.php on line 72
[22-Sep-2012 22:30:34] PHP Parse error: syntax error, unexpected T_REQUIRE in /home/pnaples9/public_html/spa/includes/templates/custom/templates/tpl_product_info_display.php on line 1

DrByte:

The error message is telling you that your english.php file is missing.

I commented out the code on line 72 because I don't have a custom english.php file. Now only the parse error shows.

Are you attempting to add a mod? If so which one, and are you merging files or just overwriting.

I commented out the code on line 72 because I don't have a custom english.php file. If you don't have a custom version, then the code will look for the stock version (which is what the error message says is missing). You can't disable some code and expect to have the rest still function correctly, unless you know that nothing else depends on the disabled code.

It's strange because the english.php isn't missing. Plus the comments in the php file say that you may have to disable the code.

I think you should start by solving this problem first

[22-Sep-2012 22:30:34] PHP Parse error: syntax error, unexpected T_REQUIRE in /home/pnaples9/public_html/spa/includes/templates/custom/templates/tpl_product_info_display.php on line 1

chances are it will solve the other problem to. Like picandnix asked, were you installing any mods? Which file is the require statement asking for?

I am not installing any mods; I am using the file override system for custom templates. Also I seemed to have found the culprit. The tpl_product_info.php file code had been transformed to fit all on one line. Sections with comments got intermingled with actual code, etc., etc., ...
Let you know...

capncrunch0:

I commented out the code on line 72 because I don't have a custom english.php file. Now only the parse error shows.

That is the wrong thing to do. Line 72 is important. It is not your problem; it is only "the messenger".
You'll need to undo that commenting.

The error message is telling you that it's looking for the MAIN english.php file, not a "custom" one.

First thing I'd do right now is go back and check all your files to make sure all the original files ARE actually present on your server. Anything you deleted should be put back. Anything that failed to upload correctly needs to be fixed.
Then I'd also check all your files to undo anything you changed while "troubleshooting". Making guesses at changing any original core files has probably taken you in the wrong direction.
Then look at all the files you've added (whether yourself or via a plugin) and determine what errors you've made in those files.

Yeah, I was using a tpl_product_info_display.php from a previous customized version of Zen Cart. I still don't know how the code got put into one horizontal line though. I deleted the file from the override folder (realizing that there was nothing custom about it). The links load the products now.

Thanks for the advice & helping me walk through the troubleshooting. Thank you for the tips also.