shopping_cart logic - Help please

[strelitzia]

I'm porting my first mod from OSC, and i'm trying to work through some code changes that the mod makes to the shopping_cart.php file in OSC. Having done some digging, i've found that zen cart uses two files to create the shopping_cart output. modules\pages\shopping_cart\header_php.php and templates\tpl_shopping_cart_default.php.
The issue i have is that i don't want to put sql queries in the tpl file, as it appears they belong in the header_php file, but if i put them in there, then i can't get any output from the variables. Am i supposed to be collecting all the information into an array that is passed to the tpl_ file, or is it called in another way?

Hope that's clear enough.

Thanks in advance for any advice

Steve

[CJPinder]

Hi,

The best thing to do is to not add anything to the template or the header but to use an observer/notifier.

There is a load of information in the wiki....
http://www.zen-cart.com/wiki/index.p...Observer_Class
...including examples that show how to do things with the shopping cart.

Using an observer/notifier means that your contribution will touch less of the Zen Cart files and be easier to install and work better with upgrades.

Regards,
Christian.

[DrByte]

Christian's right - using the observer/notifier system is a less-intrusive way of expanding functionality.

However, that said, any variables you create in the header_php.php file should still be accessible in the tpl template file for that page. There's no need to use an array to pass data unless it's array-type data. An array is just another variable anyway, so creating another variable shouldn't be a problem.

[strelitzia]

I've had a good read of the info on the Wiki, which is very useful, but leaves me with one question. Using the observer/notifier system, can you insert code in these files to structure the layout of the data that is created, or is it purely for logic code? If it is only for logic code, am i forced to hack core files to format the output as required?

Thanks
Steve

[DrByte]

What you'll need to do is really determined by what you want to accomplish -- which you haven't shared.

[strelitzia]

What i'm trying to achieve is a port of the OScommerce Dangling Carrot mod, but with a few enhancements to its functionality. As it runs on OSC, it displays information in the shopping cart to show that you are close to the threshold for a gift, or you have reached the threshold and are now entitled to 'x' product. Modifications to the OSC mod will enable the site owner to set a discounted price for the gift through admin, so if for instance you spend $100 you can have 'y' product for $10 instead of $20. I realise that there are similar ideas presented on the wiki, but they lack the functionality that i am looking to put into the Dangling Carrot module.

Thanks
Steve

[DrByte]

Okay.

What kinds of variables are you adding to the header_php.php that aren't showing up when the template is run? Is "everything" you added not showing up, or just "some" pieces? Perhaps some of your vars aren't echoing what you expected because you're not filling them with information properly ... ie: incorrect syntax on a loop through database results, etc.

One handy option you have with something like this is to put all your custom variable code into a new file named main_template_vars.php in the same folder as the header_php.php. All your vars can be built there, queries run, etc, and not have to touch the header_php.php file.
The header file is used mainly to establish prerequisites prior to the templating system kicking in to draw page content. If a page-redirect would be required, you need to know about it in the header_php stage so that no output goes to the browser and thus blocks the redirect etc.
The one drawback to using a main_template_vars file is that you'll need to manually call the template file at the end of it. Peek at /includes/modules/pages/specials/main_template_vars.php as an example of some queries running and vars being set, and then calling the template file.

[clydejones]

What i'm trying to achieve is a port of the OScommerce Dangling Carrot mod, but with a few enhancements to its functionality. As it runs on OSC, it displays information in the shopping cart to show that you are close to the threshold for a gift, or you have reached the threshold and are now entitled to 'x' product. Modifications to the OSC mod will enable the site owner to set a discounted price for the gift through admin, so if for instance you spend $100 you can have 'y' product for $10 instead of $20. I realise that there are similar ideas presented on the wiki, but they lack the functionality that i am looking to put into the Dangling Carrot module.

Thanks
Steve

There's this contribution in the downloads section that might be helpful to you.

[strelitzia]

And which mod would that be Clyde as it's not a link :-O

Might be able to take a peek at the code..see if i can use any of it.

Thanks

Steve

[clydejones]

And which mod would that be Clyde as it's not a link :-O

Might be able to take a peek at the code..see if i can use any of it.

Thanks

Steve

Sorry 'bout that, here's the link

Shopping Cart Free-Shipping-Qualifier Sidebox