HTML_QuickForm with Smarty Quickstart

I've been wanting to play with HTML_QuickForm for quite some time, but the documentation has looked rather sparse and scary regarding the use of HTML_QuickForm with Smarty. Since I've been busy at work, and I haven't wanted to take the time to learn a new library, I've simply been putting it off.

Last night, I browsed through the package documentation, and noticed a link to an HTML_QuickForm Getting Started Guide by Keith Edmunds. I was pleased to discover that he also has a guide to using Smarty with HTML_QuickForm. I got started with these tutorials, and found them excellent. I found myself wanting a little more meat afterwards, and found that I could now turn to the PEAR docs and actually make sense of it all.

While I think Mr. Edmunds tutorials are great for starters, I found that there were a few pointers I could have used right off the bat. I present them here for you.

I'm not going to do any code samples; at this point, you should have read the aformentioned tutorials. The following notes are to give a little more information to help get you running faster with HTML_Quickform + Smarty -- by giving some practical tools and steps for utilizing the combo.

The way I see it, creating and using forms with HTML_QuickForm + Smarty uses the following steps:

  1. Create the form elements. This is done via the 'addElement()' method of HQF, and involves setting a form element type, name, and label.
  2. Create form input filters (Optional). This is done via the 'applyFilter()' method of HQF; commonly, you may want to trim() input, and, if magic_quotes are on, stripslashes().
  3. Create validation rules. This is done via the 'addRule()' method, which takes the element name, the text to display on error, and the rule type as arguments (and a fourth argument if required by the rule type). There's some really slick stuff you can do here:
    • You can add more than one rule to any given element. For instance, a particular element may need to be both 'required' and match a given regex; you can add rules for both of these
    • The regex rule lets you pass a fourth argument to addRule() with the regex the value should match.
    • The email rule makes it so you don't have to remember a regex for emails every time you write a form.
  4. Test for validation. What I discovered is that it's actually nice to do this as an if-then-else block. This allows you to do different things based on whether or not the $form->validate() succeeds; for instance, you may not wish to display the same template on success as on failure. For certain, you will not need to do anything with the renderer if the form validates (assuming you don't display the form or its values again).
  5. Set renderer options. Basically, if the form fails validation, you'll need to display it again. Most likely, you want to display something new back to the user: what elements had errors, and the error message for them. Additionally, you may want to show which elements are required. Each renderer supplies several methods to allow such customization. These methods each can display elements:
    • {$label} -- the form element's label
    • {$html} -- the HTML for the form element
    • {$error} -- the error text for the form element
    • {$required} -- a flag indicating whether or not an element is required
    If either the {$label} or {$html} element is referenced in the template passed to one of these methods, the appropriate field (label or html) for that form element will be affected before being passed to the master form template.

    The following methods are supplied by a renderer class:
    • setRequiredTemplate(). Pass it a template as a string; this template will be called for each required element. So, you'll typically want to modify the {$label} element in the template, usually with some sort of flag, like an asterix.
    • setErrorTemplate(). Pass it a template as a string; this template will be displayed if an error occurs for a given element. Again, like setRequiredTemplate(), you'll typically want to modify the label, this time by appending the error string.
    • setRequiredNote(). Pass it a template as a string; this template can be displayed by calling the $form_data.requirednote field in the template (assuming you assign your form data to $form_data). This should be simply some text to the effect of '* These fields are required.' (and really, in a Smarty template, this probably isn't necessary).
  6. Freeze and Process. If the form validates, you should then freeze it, and, if necessary, process the submission. HQF has a method, 'process()', that allows you to pass the values to a callback. However, you might find it easiest to simply take the values and process them yourself. You can do this easily and safely with the exportValues() method, which returns an associative array with form key => value pairs as they exist post filtering; additionally, it will only pass an array containing those elements handled by the form (i.e., no other values, even if passed, will be returned).

Parting Notes

To my thinking, a config script/class/file could be written that would perform the first three steps, defining the form elements, their filters, and their validations; this could even be extended to handle the renderer options. Then, it would be a simple matter of calling that, testing for validation, and then either re-displaying the form or processing it with the values returned.

(I'll probably use the above to create a Cgiapp plugin for just this very purpose, similar in nature to CGI::Applications Data::FormValidator plugin.)

blog comments powered by Disqus