I don’t know about you, but I find that sometimes coding html forms and the corresponding backend validation to be the typical type of “Boiler Plate” code that once you’ve done it and understand the principles, that you never really want to have to do it again.

Into the breach steps Zend_Frameworks’ Zend_Validate and also Zend_Filter. This set of classes can be used in conjunction with the Zend_Form_Element Classes and Zend_Form Class and makes validating forms almost a pleasure. Let me show you an example.

Often with a web form we need to validate that an email address is valid. So you might use a function such as:

filter_var($email, FILTER_VALIDATE_EMAIL)

And then redirect back with an error stored in the user’s session if it fails. However it gets a little more tricky when you also need to validate that the email address is unique to your database table.

public function validateUsersEmail(){
if(filter_var($this->email, FILTER_VALIDATE_EMAIL)){
//do query to check email address not already entered
//if no return true
return false;

However Zend Framework offers a set of very powerful filters. which means you can create a form email like so from within a class extending Zend_Form:

$handleElement = new Zend_Form_Element_Text("handle");
//Here is where the validator kicks in
$handDbValidator = new Zend_Validate_Db_NoRecordExists('siteusers','handle');
$handDbValidator->setMessage("That username already exists");
->addFilter(new Zend_Filter_Alnum(false))
->addFilter(new Zend_Filter_StripTags())
->addFilter(new Zend_Filter_StringTrim());

Now that looks like a lot of code. However there are several validators and also filters being applied to this element.

Here is the code for checking if a record exists and also to set the error message to report to the user

$handDbValidator = new Zend_Validate_Db_NoRecordExists('siteusers','handle');
$handDbValidator->setMessage("That username already exists");

Here we specify the table name and the field name to check and then add an error message if it fails.

Now the filters

So how often have you gone searching for the right regular expression to strip out all none alpha numeric characters from a string? Well I know I often forget the exact syntax and go searching. Zend Framework offers you a great set of Filters to apply to your form elements. In the above code you can see them at work in the following way:

->addFilter(new Zend_Filter_Alnum(false))
->addFilter(new Zend_Filter_StripTags())

These are fairly self explanatory but show what is possible using the Zend_Form Class along with filters and validators.

You can find out more on validators and also Filters by following the links.

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