Getting Started with PHP's HTML_QuickForm
Pages: 1, 2
Adding Rules and Filters
In the simplest case, I wanted to ensure that the user really had entered a
name before clicking the Submit button. To accomplish this, I called an
addRule method of the form:
$form->addRule('txtName', 'Please enter your name', 'required');
The first argument is the name of the element to apply the rule to, the
second is the error text to display if the rule fails, and the third is the
type of rule to apply. This will require a value for
it must not be blank. When the form displays, it will indicate that this is a
required field. By default, a red asterisk will appear next to the field that
refers to a note at the foot of the form. If
txtName is blank,
validate method call will return
false. This in
turn will cause the form to redisplay, but now the error text (the second
parameter to the
addRule method) will display above the field
that failed the validation.
By adding that one line of code, we can show the user which fields are
mandatory, we can check that the user has filled them in, and we can provide
feedback to the user in the event that they have not filled them all in. There
are other built-in rules, including:
Suppose, however, that the user merely inserts a space in the
txtName field. The validation will still pass because the field is
not blank, but this is hardly what we want. There are other rules we could use
-- for example, the
regex rule checks the input against a
regular expression, but that is complex way to solve a simple problem.
A better way approach is to use filters. A filter can be either the
name of a user-supplied function or the name of a PHP built-in function.
QuickForm will send the contents of the text field to this function before
validation. In this case, the PHP function
trim does precisely
what we want by removing all leading and trailing spaces. Here it is in
$form->addRule('txtName', 'Please enter your name', 'required'); $form->applyFilter('txtName', 'trim');
applyFilter method takes two arguments: the name of the
element to apply the filter to, and the name of the filter, as described above.
The element name can be the pseudo-element
__ALL__, which, as you
might expect, applies that filter to all elements.
One of the elements on the form I designed was a checkbox that indicated
whether the person wanted to subscribe to a mailing list. The validation
required here is not so simple: the
EmailAddress field should contain either a
valid email address or nothing, but if the user has checked the
EmailAddress field must not be blank.
We can achieve this with a different built-in rule in conjunction with a user-defined validation rule, as follows (see Example 1).
There's quite a lot extra here. First, I've added a couple of new elements:
a text box for the user's email address and an
requesting a newsletter. The
advcheckbox is a special
HTML_QuickForm element. The problem with an ordinary checkbox is that it
returns no value at all if left unchecked, making it more difficult to check in
code; however, the advanced checkbox will always return a value, either
FALSE, as appropriate.
I've added a filter rule to remove leading and trailing spaces from all data
entered. There are two element-specific rules: one to ensure that the user has
entered a name, and the other,
required, would also apply to the field. As
it stands, the validation routine will only check that the format of the email
address is legal. By specifying an additional parameter, the validation routine
can also check whether the address given really exists.
Finally, we have a new method,
addFormRule. This takes a single
argument, the name of a user-written function that will help validate the form.
newcontact_validate, takes a single parameter in
the form of an associative array consisting of
element-name=>element-value pairs. This function returns either
TRUE, indicating that validation has passed, or an associative array of
In this particular example, we only check that the user has supplied an
email address if they have elected to receive a newsletter. However, the format
of this function is generic enough to perform more complex validations. In the
example shown, we first define an array in which to store any errors we find.
We then carry out the checks, adding an element name and error message to the
errors array for each validation error found. At the end of the
function, we check the
errors array and either return it if there
are errors, or return
true if everything validated. Any errors
returned by the
addFormRule function display in the same way as
built-in validation rule failures.
My form was almost complete. It worked well for entering details of new
contacts, but I also wanted to use it to edit details of existing contacts. I
needed a way to populate the fields with existing data. To accomplish this, I
setDefaults method (see Example
There are a few changes here, starting with the definition of some user data
in the array
$user. I'd normally retrieve this from a database,
but for clarity I have hard-coded it here. The form definition resembles the
previous version, but I have changed the element names to match the column
names in my database. For example,
txtName has become simply
name. There is also a new element,
hidden. As the
name implies, this is a hidden element on the form. In this case, it stores the
key field in the database to use in the resulting SQL
The final change is the
setDefaults method. This takes a single
argument, an associative array of
pairs. Using the same name for both the database fields and the element names
on the form greatly simplifies the population of default values and the later
building of the SQL
UPDATE statement. Any element that does not appear in the
array passed with
setDefaults retains its default (typically
blank) value, so the same code can both create contacts (passing an empty
defaults array) and edit contacts.
I now have a form which is in daily use. It consists of pure PHP code with none of the lack of clarity which can arise from mixing PHP and HTML code in the same file. My users use the same code both to create and edit contacts, which makes the application more consistent in its appearance and easier to maintain. All of the input fields are validated with very little code, and users receive good feedback if any of the validations fail.
You can find out more about PEAR at the PEAR web site and from the online PEAR manual. In this article,
I have only scratched the surface of what can be achieved by PEAR's
HTML_QuickForm classes. There's a lot more power available there. With the
addition of templates, the resulting forms can look very professional --
but perhaps that is a subject for another time.
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