Demonstrates validating multiple fields of the form created by the framework. This is a sample plugin introduced in the tutorial, Validate Submitted Form Data of Multiple Fields (http://en.michaeluno.jp/admin-page-framework/tutorials-v3/08-validate-submitted-form-data-of-multiple-fields/).

tutorials-08-validate-multiple-fields.php

<?php
/*
 *  Plugin Name:    Admin Page Framework Tutorial 08 - Validate Submitted Form Data
 *  Plugin URI:     http://en.michaeluno.jp/admin-page-framework
 *  Description:    Validate the form data of a section.
 *  Author:         Michael Uno
 *  Author URI:     http://michaeluno.jp
 *  Version:        1.0.1
 *  Requirements:   PHP 5.2.4 or above, WordPress 3.4 or above. Admin Page Framework 3.0.6 or above
 */

// Set your own path here
include( dirname( __FILE__ ) . '/library/apf/admin-page-framework.php' );    
    
class APF_ValidateFields extends AdminPageFramework {

    public function setUp() {
        
        $this->setRootMenuPageBySlug( 'APF_ValidateSingleField' );    // where to belong
        $this->addSubMenuItem(
            array(
                'title'        => __( '8. Validate Fields', 'admin-page-framework-tutorials' ),    // page and menu title
                'page_slug'    => 'apf_tutorial_fields_validation'    // page slug
            )
        );

        $this->addSettingSections(    
            array(
                'section_id'   => 'text_section',    
                'page_slug'    => 'apf_tutorial_fields_validation',    
            )
        );
        
        $this->addSettingFields(
            'text_section',    // the target section ID
            array(    
                'field_id'    => 'alpanumeric',
                'title'       => __( 'Alpanumeric', 'admin-page-framework-tutorials' ),
                'type'        => 'text',
            ),                   
            array(               
                'field_id'    => 'no_html',
                'title'       => __( 'No HTML', 'admin-page-framework-tutorials' ),
                'type'        => 'textarea',
            ),                   
            array(               
                'field_id'    => 'submit',
                'type'        => 'submit',
            )
        );
    }
    
    /**
    * The pre-defined validation callback method.
    *
    * Notice that the name of the method is made up of validation_{instantiated class name}_{section id}.
    * 
    * The following hooks are available:
    * - validation_{instantiated class name}_{field id} – [3.0.0+] receives the form submission value of the field that does not have a section. The first parameter: ( string|array ) submitted input value. The second parameter: ( string|array ) the old value stored in the database.
    * - validation_{instantiated class name}_{section_id}_{field id} – [3.0.0+] receives the form submission value of the field that has a section. The first parameter: ( string|array ) submitted input value. The second parameter: ( string|array ) the old value stored in the database.
    * - validation_{instantiated class name}_{section id} – [3.0.0+] receives the form submission values that belongs to the section.. The first parameter: ( array ) the array of submitted input values that belong to the section. The second parameter: ( array ) the array of the old values stored in the database.
    * - validation_{page slug}_{tab slug} – receives the form submission values as array. The first parameter: submitted input array. The second parameter: the original array stored in the database.
    * - validation_{page slug} – receives the form submission values as array. The first parameter: submitted input array. The second parameter: the original array stored in the database.
    * - validation_{instantiated class name} – receives the form submission values as array. The first parameter: submitted input array. The second parameter: the original array stored in the database.
    * 
    * @param    array    $aInputs        The submitted field array.
    * @param    array    $aOldInputs    The stored field array.
    * @callback filter   validation_{instantiated class name}_{section id}
    */
    public function validation_APF_ValidateFields_text_section( $aInputs, $aOldInputs, $oFactory, $aSubmitInfo ) {    
        
        // Prepare a flag and a field error array.
        $_fIsValid = true;
        $_aErrors = array();
        
        // Check if the value is alphabetical & numeric
        if ( isset( $aInputs[ 'alpanumeric' ] ) && ! ctype_alnum( $aInputs[ 'alpanumeric' ] ) ) {
            
            $_fIsValid = false;
            
            // $variable[ 'sectioni_id' ][ 'field_id' ]
            $_aErrors[ 'text_section' ][ 'alpanumeric' ] = __( 'The value must be alphabetic and numeric:', 'admin-page-framework-tutorials' ) . ' ' . $aInputs[ 'alpanumeric' ];
            
        }
        
        // Sanitize the value - strip HTML tags
        $aInputs[ 'no_html' ] = isset( $aInputs[ 'no_html' ] ) ? strip_tags( $aInputs[ 'no_html' ] ) : '';
                
        // An invalid value is found.
        if ( ! $_fIsValid ) {
            
            // Set the error array for the input fields.
            $this->setFieldErrors( $_aErrors );    
            $this->setSettingNotice( __( 'There was something wrong with your input.', 'admin-page-framework-tutorials' ) );
            return $aOldInputs;
            
        }    
        
        // The return values will be saved in the database. 
        return $aInputs;
        
    }        
                
}

new APF_ValidateFields;