In Part 1 of this tutorial, we covered the basics of our Form Validation Class.  We explained how the core of the Class depends on regular expressions and gave an insight regarding the keyword concept. We also explained how each keyword will have a corresponding Class Method so that we can easily extend the Class in the future to suit our needs.

In Part 2, we will get our hands dirty in creating the remaining useful Class Methods that will instruct the Class which form fields to validate and how to validate them.

In comparison to Part 1, this Part is significantly shorter, easier, and to the point.


Adding Fields To Be Validated
To use our Class in a development environment, we must somehow provide a way for the programmer to instruct the Class which form fields to validate upon submission.

This will be done via a new Class Method we will now create called addFormField( ).


The addFormField( ) Method
Our Method will accept two arguments, the name of the form field and the keywords for it. Let's look at the code and then explain each section.

In Part 1, we explained that all form data sent by PHP is either saved in a $POST or $GET Super Global. To make life easier for us, we save this data in a Class Attribute depending on the form method so we do not always have to check both Super Global's.

We want to add some sort of error check to our Class, to avoid adding non existent fields. This is to ensure that our Class will run at the fastest possible speeds. If non existent fields are allowed to be added, not only will PHP parser warning be generated, but our Class will loop through an endless number of form fields that simply do not exist.

In the above code segment, we make sure the form was submitted, there hence making sure that there is some sort of form data to work with. Technically we can skip the top step, since the next code segment also does some sort of error check, but leaving it won't hurt.

Again here we make use of the PHP function array_key_exists( ). If you remember from Part 1, we said that the array housing our form data has as keys each form field name.

So by checking that there is a key with our form field name that we wish to add does indeed exist in our array, we make sure that we are not adding a non existent field. The above code segment returns a Class system error message if the key does not exist.

Having made sure that no errors will be encountered when adding a new field, we then proceed to add a new field to our array, with the keywords included. This is a two step process.

First we add to our array a new key with a value of the keywords followed by the field name. Then we remove the old key to avoid any errors.

What does this mean? Well, let's say in our array we had a key of Email and we wanted to add a keyword of (Required). We will create a new key in our array called (Required)Email then remove the old key of Email alone. This is exactly what we have done in the code below.

<?php         // Add Keywords.         $this->_f_data[ $keyword . $fName ] = $this->_f_data[ $fName ];         // Remove Form Field Name Without Keywords.         unset( $this->_f_data[ $fName ] ); ?>

- Tutorial written by Limitless

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