PHP Form Validation Script
It is very essential to have the input to your form validated before taking the
form submission data for further processing.
When there are many fields in the form, the PHP
validation script becomes too complex. Moreover, since you are doing the
same or similar validation for most of the forms that you make, just too much of
duplicate effort is spent on form validations.
About this generic PHP form validation script
The generic PHP form validator makes it very easy to add validations to your form.
We create and associate a set of "validation descriptors" with each element
in the form. The "validation descriptor" is a string specifying the type of
validation to be performed. For example, "req" means required, "alpha" means
allow only alphabetic characters and so on.
Each field in the form can have 0, 1, or more validations. For example, the input should
not be empty, should be less than 25 chars, should be alpha-numeric, etc
You can associate a set of validation descriptors for each input field in the form.
Download the PHP form validation script
You can download the PHP form validation script below:
php-form-validator.zip
The zip file contains the form validation script formvalidator.php, documentation and
usage samples.
Using the PHP form validation script
- Include formvalidator.php in your form processing script
require_once "formvalidator.php";
- Create a FormValidator object and add the form validation descriptors.
$validator = new FormValidator();
$validator->addValidation("Name","req","Please fill in Name");
$validator->addValidation("Email","email","The input for Email should be a valid email value");
$validator->addValidation("Email","req","Please fill in Email");
The first argument is the name of the input field in the form. The second argument
is the validation descriptor that tells the type of the validation required.
The third argument is the error message to be displayed if the validation fails.
- Validate the form by calling ValidateForm() function
if(!$validator->ValidateForm())
{
echo "<B>Validation Errors:</B>";
$error_hash = $validator->GetErrors();
foreach($error_hash as $inpname => $inp_err)
{
echo "<p>$inpname : $inp_err</p>\n";
}
}
Example
The example below will make the idea clearer
<?PHP
require_once "formvalidator.php";
$show_form=true;
if(isset($_POST['Submit']))
{
$validator = new FormValidator();
$validator->addValidation("Name","req","Please fill in Name");
$validator->addValidation("Email","email","The input for Email should be a valid email value");
$validator->addValidation("Email","req","Please fill in Email");
if($validator->ValidateForm())
{
echo "<h2>Validation Success!</h2>";
$show_form=false;
}
else
{
echo "<B>Validation Errors:</B>";
$error_hash = $validator->GetErrors();
foreach($error_hash as $inpname => $inp_err)
{
echo "<p>$inpname : $inp_err</p>\n";
}
}
}
if(true == $show_form)
{
?>
<form name='test' method='POST' action='' accept-charset='UTF-8'>
Name: <input type='text' name='Name' size='20'>
Email: <input type='text' name='Email' size='20'>
<input type='submit' name='Submit' value='Submit'>
</form>
<?PHP
}//true == $show_form
?>
Adding Custom Validation
If you want to add a custom validation, which is not provided by the validation descriptors,
you can do so. Here are the steps:
- Create a class for the custom validation and override the DoValidate() function
class MyValidator extends CustomValidator
{
function DoValidate(&$formars,&$error_hash)
{
if(stristr($formars['Comments'],'http://'))
{
$error_hash['Comments']="No URLs allowed in comments";
return false;
}
return true;
}
}
- Add the custom validation object
$validator = new FormValidator();
$validator->addValidation("Name","req","Please fill in Name");
$validator->addValidation("Email","email","The input for Email should be a valid email value");
$validator->addValidation("Email","req","Please fill in Email");
$custom_validator = new MyValidator();
$validator->AddCustomValidator($custom_validator);
The custom validation function will be called automatically after other validations.
Table of Validation Descriptors
|
req
|
The field should not be
empty
|
|
maxlen=???
|
checks the length entered data to the maximum. For
example, if the maximum size permitted is 25, give the validation descriptor as "maxlen=25"
|
|
minlen=???
|
checks the length of the entered string to the
required minimum. example "minlen=5"
|
|
alnum
|
Check the data if it
contains any other characters other than alphabetic or numeric characters
|
|
alnum_s
|
Allows only alphabetic, numeric and space characters
|
| num
|
Check numeric data
|
| alpha
|
Check alphabetic data.
|
| alpha_s
|
Check alphabetic data and allow spaces.
|
| email
|
The field is an email
field and verify the validity of the data.
|
lt=???
lessthan=???
|
Verify the data to be less than the value passed.
Valid only for numeric fields.
example: if the
value should be less than 1000 give validation description as "lt=1000"
|
gt=???
greaterthan=??? |
Verify the data to be greater than the value passed.
Valid only for numeric fields.
example: if the
value should be greater than 10 give validation description as "gt=10"
|
| regexp=???
|
Check with a regular expression the value should match the regular expression.
example: "regexp=^[A-Za-z]{1,20}$" allow up to 20 alphabetic
characters.
|
| dontselect=??
|
This
validation descriptor is for select input items (lists)
Normally, the select list boxes will have one item saying 'Select One' or
some thing like that. The user should select an option other than this
option. If the index of this option is 0, the validation description
should be "dontselect=0"
|
| dontselectchk
|
This
validation descriptor iss for check boxes. The user should not select the
given check box. Provide the value of the check box instead of ??
For example, dontselectchk=on
|
| shouldselchk
|
This
validation descriptor is for check boxes. The user should select the
given check box. Provide the value of the check box instead of ??
For example, shouldselchk=on
|
| dontselectradio
|
This
validation descriptor iss for radio buttons. The user should not select the
given radio button. Provide the value of the radio button instead of ??
For example, dontselectradio=NO
|
| selectradio
|
This
validation descriptor is for radio buttons. The user should select the
given radio button. Provide the value of the radio button instead of ??
For example, selectradio=yes
|
| selmin=??
|
Select atleast n number of check boxes from a check box group.
For example selmin=3
|
| selmin=??
|
Select atleast n number of check boxes from a check box group.
For example: selmin=3
|
| eqelmnt=???
|
compare two elements in the form and make sure the values are the same
For example, 'password' and 'confirm password'.
Replace the ??? with the name of the other input element.
For example:
eqelmnt=confirm_pwd
|
|
|
