Using the PHP Filter function to validate but ignoring empty optional fields

Question

I want to use PHP Filter to quickly filter a form and show user feedback. Some fields in my form are necessary, some are not.

I am going to use filter_input_array() to filter all my fields. I will pass the data through several runs. That way, I can display some error messages.

I have one problem: how can I ignore empty fields that are not required? I did not see a filter for him.

Update: Clarification of requirements for filters and error messages:

I want to use filters to check:

• If all required fields are filled
• If additional fields are filled in; if not, ignore the rest of the process
• If fields, such as email, phone number, etc., are filled out.

I want to display error messages for each type of error with the maximum number of error messages in the field.

Answer 1

The filter_xyz_array () functions return NULL for an element that does not exist in the input array, for example.

 <?php $args = array( 'foo' => array( 'filter' => FILTER_VALIDATE_INT, 'flags' => FILTER_REQUIRE_ARRAY, 'options' => array('min_range' => 1, 'max_range' => 4) ), 'bar' => array( 'filter' => FILTER_VALIDATE_INT, 'flags' => FILTER_REQUIRE_SCALAR ) ); $input = array( 'foo'=>array(1,2,3,4) ); $filtered = filter_var_array($input, $args); var_dump($filtered); 

prints

 array(2) { ["foo"]=> array(4) { [0]=> int(1) [1]=> int(2) [2]=> int(3) [3]=> int(4) } ["bar"]=> NULL } 

isset () returns false for a variable / array element containing NULL. You can use this to ignore elements that have been set to NULL using filter functions.
Depending on what you are filtering and the structure of the array returned by the filter function, you can even use array_filter () to "clear" the array.

Answer 2

PHP Filters: handling optional values ​​/ optional input forms with the filter_input_array () function.

I will demonstrate a simple way to handle optional fields or form input when working with PHP filters. Rule of thumb:

• Filter all form input, required and optional. Do not leave optional fields in your filter.
• Use the comparison operator === to distinguish between FALSE, NULL, "", and 0

An example code for a simple contact form with 4 required and 4 optional inputs is shown below.

 <?php if ($_SERVER["REQUEST_METHOD"] == "POST"){ /*set validation control variable*/ $input_error_flag = true; /*set form input validation filters*/ $form_filter = array( 'first_name' => FILTER_SANITIZE_STRING, 'middle_name' => FILTER_SANITIZE_STRING, 'last_name' => FILTER_SANITIZE_STRING, 'email_address' => FILTER_SANITIZE_EMAIL, 'postal_address' => FILTER_SANITIZE_NUMBER_INT, 'street_address' => FILTER_SANITIZE_STRING, 'telephone_number' => FILTER_SANITIZE_NUMBER_INT, 'mobile_number' => FILTER_SANITIZE_NUMBER_INT, ); /*list optional fields or optional form inputs in array*/ $optional_fields = array( 'middle_name' => "", 'postal_address' => "", 'street_address' => "", 'mobile_number' => "", ); /*set error display message of each required element*/ $error_description = array( 'first_name' =>"Missing or incorrect First Name", 'last_name' =>"Missing or incorrect Last Name", 'email_address' =>"Missing or incorrect Email Address", 'telephone_number' =>"Missing or incorrect Telephone Number", ); /*sanitize all form inputs against form_filter*/ $form_data = filter_input_array(INPUT_POST, $form_filter); /*check form inputs for filter validation errors*/ foreach ($form_data as $form_input => $value){ /*check if filter failed (false), input not defined (null) or input missing ("") * and insert name of form input element into $invalid_array for error display */ if($value === FALSE || $value === NULL || $value == ""){ /*exclude error display for optional items with empty values*/ if(!(array_key_exists($form_input, $optional_fields) && $value == "")){ $invalid_inputs[] = $form_input; } } } /*unset filter validation control variable if no errors*/ if(empty ($invalid_inputs)) $input_error_flag = false; /*your calls to SQL functions for INSERT or UPDATE statements go here*/ if(!$input_error_flag){ functionname::getInstance()->insert_contact_details($form_data); } } ?> 

And finally, the html form with error display section

 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title></title> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> </head> <body> <form action="sample.php" method="POST" id="sample"> <label for="first_name">First Name*</label> <input type="text" name="first_name" id="first_name" value="<?php echo $form_data['first_name']; ?>"/><br/> <label for="middle_name">Middle Name</label> <input type="text" name="middle_name" id="middle_name" value="<?php echo $form_data['middle_name']; ?>"/><br/> <label for="last_name">Last Name*</label> <input type="text" name="last_name" id="last_name" value="<?php echo $form_data['last_name']; ?>"/><br/> <label for="email_address">Email Address*</label> <input type="text" name="email_address" id="email_address" value="<?php echo $form_data['email_address']; ?>"/><br/> <label for="postal_address">Postal Address</label> <input type="text" name="postal_address" id="postal_address" value="<?php echo $form_data['postal_address']; ?>"/><br/> <label for="street_address">Street Address</label> <input type="text" name="street_address" id="street_address" value="<?php echo $form_data['street_address']; ?>"/><br/> <label for="telephone_number">Telephone Number*</label> <input type="text" name="telephone_number" id="telephone_number" value="<?php echo $form_data['telephone_number']; ?>"/><br/> <label for="mobile_number">Mobile Number</label> <input type="text" name="mobile_number" id="mobile_number" value="<?php echo $form_data['mobile_number']; ?>"/><br/> <input type="submit" name="submit" value="submit"><br/> <?php //display input validation errors on your html form if ($input_error_flag){ foreach($invalid_inputs as $key => $form_input){ if(array_key_exists($form_input, $error_description)){ echo $error_description[$form_input]."<br/>"; } } } ?> </form> </body> </html> 

Answer 3

In the end, I used my own solution based on @VolkerK's answer. I should clarify what I want. I am updating my question with this information.

I'm still looking for an easier solution.

First, I made several arrays of results:

 // errors to display $errors = array(); // fields to ignore in the validation step $ignore_fields = array(); // return values after validation $returnvalues = array(); 

First, I filtered out the required fields:

 function required($string){ return trim($string) == "" ? false : $string; } $required_errors = array( "firstname" => "Je moet je voornaam invullen.", "lastname" => "Je moet je achternaam invullen.", "email" => "Je moet je e-mailadres invullen." ); $required_filter = array(); foreach($required_errors as $requiredfieldname => $error){ $required_filter[$requiredfieldname] = array( 'filter' => FILTER_CALLBACK, 'options' => "required", 'flags' => FILTER_NULL_ON_FAILURE ); } $required_filtered = filter_input_array(INPUT_GET | INPUT_POST, $required_filter); foreach($required_errors as $required => $error){ if(!isset($required_filtered[$required])){ $errors[$required] = $required_errors[$required]; $returnvalues[$required] = ""; $ignore_fields[$required] = "ignored"; // value doesn't matter } } 

Then check the empty fields and load them with the default value

 // ignore the other fields if they are empty; // the actual form has about 10 values here $maybeempty = array("from", "to", "phonenumber"); $optional_defaultvalue = array( "from" => 0, "to" => 0, "phonenumber" => "", ); $optional_filter = array(); foreach($maybeempty as $field){ $required_filter[$requiredfieldname] = array( 'filter' => FILTER_CALLBACK, 'options' => "required", 'flags' => FILTER_NULL_ON_FAILURE ); } $optional_filtered = filter_input_array(INPUT_GET | INPUT_POST, $required_filter); foreach($maybeempty as $field){ if(!isset($optional_filtered[$field])){ $ignore_fields[$field] = "ignored"; // value doesn't matter $returnvalue[$field] = $optional_defaultvalue[$field]; } } 

In the last step, I will create an array of checks, custom error messages, and ignore ignore fields to skip empty fields or fields that already had an error:

  $validity_filter = array( 'email' => array( 'filter' => FILTER_VALIDATE_EMAIL, 'flags' => FILTER_REQUIRE_SCALAR ), 'from' => array( 'filter' => FILTER_VALIDATE_INT, 'flags' => FILTER_REQUIRE_SCALAR, 'options' => array('min_range' => 1964, 'max_range' => 2009)), 'to' => array( 'filter' => FILTER_VALIDATE_INT, 'flags' => FILTER_REQUIRE_SCALAR, 'options' => array('min_range' => 1964, 'max_range' => 2009)) ); // filter all ignored fields $validity_filter = array_diff_key($validity_filter, $ignore_fields); $validity_filtered = filter_input_array(INPUT_GET | INPUT_POST, $required_filter); foreach($validity_filter as $field => $value){ if($value === false){ // NULL values are checked in a previous step $errors[$field] = $validity_errors[$field]; // show error $returnvalues[$field] = $_REQUEST[$field]; // return original value } else { $returnvalues[$field] = $value; // return filtered value } } // process possible errors and response values