Description

Features:

• simply generate post boxes with multiple fields / groups
• easily validate/sanitize input and output data
• easy access to field data via $easy_cf->field_id->get() or $easy_cf->field_id->get( NULL, $raw=true );
• get error messages for validation failures via admin notices
• custom post type aware
• extendable to your needs by extending Easy_CF_Field and Easy_CF_Validator classes (see advanced usage)

As this script is mainly meant as basis for developers it needs minor coding skills to add this functionality
to your theme.

In order to make use of this class simply initialize it from the functions.php file of your theme as described below.

Simple Usage

require_once( WP_PLUGIN_DIR . '/easy-custom-fields/easy-custom-fields.php' );
$field_data = array (
    'testgroup' => array (              // unique group id
        'fields' => array(              // array "fields" with field definitions
            'field1'    => array(),     // globally unique field id
            'field2'    => array(),
            'field3'    => array(),
        ),
    ),
);
$easy_cf = new Easy_CF($field_data);

Advanced Usage

require_once( WP_PLUGIN_DIR . '/easy-custom-fields/easy-custom-fields.php' );
$field_data = array (
    'testgroup' => array (
        'fields' => array(
            'field1'    => array(),
            'field2'    => array(),
            'field3'    => array(),
        ),
    ),
    'advanced_testgroup' => array (                                     // unique group id
        'fields' => array(                                              // array "fields" with field definitions 
            'advanced_field'    => array(                               // globally unique field id
                'label'         => 'Advanced Field Description',        // Field Label
                'hint'          => 'Long Advanced Field description',   // A descriptive hint for the field
                'type'          => 'textarea',                          // Custom Field Type (see Ref: field_type)
                'class'         => 'aclass',                            // CSS Wrapper class for the field
                'input_class'   => 'theEditor',                         // CSS class for the input field
                'error_msg'     => 'The Advanced Field is wrong' ),     // Error message to show when validate fails
                'validate'      => 'validatorname',                     // Custom Validator (see Ref: validator)
            'advanced_email' => array(
                'label' => 'Email',
                'hint' => 'Enter your email',
                'validate' => 'email', )
        ),
        'title' => 'Product Description',   // Group Title
        'context' => 'advanced',            // context as in https://codex.wordpress.org/Function_Reference/add_meta_box
        'pages' => array( 'post', 'page' ), // pages as in https://codex.wordpress.org/Function_Reference/add_meta_box
    ),
);

if ( !class_exists( "Easy_CF_Validator_Email" ) ) {

    class Easy_CF_Validator_Email extends Easy_CF_Validator {
        public function get( $value='' ) {
            return esc_attr( $value );
        }

        public function set( $value='' ) {
            $value = esc_attr( trim( stripslashes( $value ) ) );
            return $value;
        }

        public function validate( $value='' ) {
            if ( empty( $value ) || is_email( $value ) ) 
                return true;
            else
                return false;
        }
    }
}

if ( !class_exists( "Easy_CF_Field_Textarea" ) ) {
    class Easy_CF_Field_Textarea extends Easy_CF_Field {
        public function print_form() {
            $class = ( empty( $this->_field_data['class'] ) ) ? $this->_field_data['id'] . '_class' :  $this->_field_data['class'];
            $input_class = ( empty( $this->_field_data['input_class'] ) ) ? $this->_field_data['id'] . '_input_class' :  $this->_field_data['input_class'];

            $id = ( empty( $this->_field_data['id'] ) ) ? $this->_field_data['id'] :  $this->_field_data['id'];
            $label = ( empty( $this->_field_data['label'] ) ) ? $this->_field_data['id'] :  $this->_field_data['label'];
            $value = $this->get();
            $hint = ( empty( $this->_field_data['hint'] ) ) ? '' :  '<p><em>' . $this->_field_data['hint'] . '</em></p>';

            $label_format =
                '<div class="%s">'.
                '<p><label for="%s"><strong>%s</strong></label></p>'.
                '<p><textarea class="%s" style="width: 100%%;" type="text" name="%s">%s</textarea></p>'.
                '%s'.
                '</div>';
            printf( $label_format, $class, $id, $label, $input_class, $id, $value, $hint );
        }
    }
}

$easy_cf = new Easy_CF($field_data);

Note

If you’re not using auto_init then meta boxes need to be added individually using
add_meta_box( $group_id, $group_title, array( &$easy_cf, ‘meta_box_cb’ ), $page, $group_context );
and the save methods need to be initialized after adding all meta boxes using
$easy_cf->add_save_method();