Multiple select product using select2 for wordpress plugin option page - wordpress

Question

I am trying to implement multiple select product using select2 . the list come up using getproductsearch this ajax action i did earlier but i failed to save it. I did this feature before for post-meta and product-category but failed for plugin option page. I am not sure what i am doing wrong.
please help.
class FeatureSale {
private $feature_sale_options;
public function __construct() {
add_action( 'admin_menu', array( $this, 'feature_sale_add_plugin_page' ) );
add_action( 'admin_init', array( $this, 'feature_sale_page_init' ) );
}
public function feature_sale_add_plugin_page() {
add_submenu_page(
'exclutips-settings',
'Feature & Sale', // page_title
'Feature & Sale', // menu_title
'manage_options', // capability
'feature-sale', // menu_slug
array( $this, 'feature_sale_create_admin_page' ) // function
);
}
public function feature_sale_create_admin_page() {
$this->feature_sale_options = get_option( 'feature_sale_option_name' ); ?>
<div class="wrap">
<div class="catbox-area-admin" style="width: 500px;background: #fff;padding: 27px 50px;">
<h2>Feature & Sale</h2>
<p></p>
<?php settings_errors(); ?>
<form method="post" action="options.php">
<?php
settings_fields( 'feature_sale_option_group' );
do_settings_sections( 'feature-sale-admin' );
submit_button();
?>
</form>
</div>
</div>
<?php }
public function feature_sale_page_init() {
register_setting(
'feature_sale_option_group', // option_group
'feature_sale_option_name', // option_name
array( $this, 'feature_sale_sanitize' ) // sanitize_callback
);
add_settings_section(
'feature_sale_setting_section', // id
'', // title
array( $this, 'feature_sale_section_info' ), // callback
'feature-sale-admin' // page
);
add_settings_field(
'vpm_sale_product', // id
'VPM Sale Product', // title
array( $this, 'vpm_sale_product_callback' ), // callback
'feature-sale-admin', // page
'feature_sale_setting_section' // section
);
add_settings_field(
'vpm_featured_product', // id
'VPM Featured Product', // title
array( $this, 'vpm_featured_product_callback' ), // callback
'feature-sale-admin', // page
'feature_sale_setting_section' // section
);
}
public function feature_sale_sanitize($input) {
$sanitary_values = array();
if ( isset( $input['vpm_sale_product'] ) ) {
$sanitary_values['vpm_sale_product'] = $input['vpm_sale_product'];
}
if ( isset( $input['vpm_featured_product'] ) ) {
$sanitary_values['vpm_featured_product'] = $input['vpm_featured_product'];
}
return $sanitary_values;
}
public function feature_sale_section_info() {
}
//Output the HTML for the metabox.
public function vpm_sale_product_callback() {
global $post;
// Nonce field to validate form request came from current site
wp_nonce_field( basename( __FILE__ ), 'vpm_sale_product_nonce' );
$html = '';
// always array because we have added [] to our <select> name attribute
$feature_sale_options = get_option( 'feature_sale_option_name' ); // Array of All Options
$vpm_sale_product = $feature_sale_options['vpm_sale_product'];
$html .= '<p><select id="vpm_sale_product" name="vpm_sale_product[]" multiple="multiple" style="width:99%;max-width:25em;">';
if( $vpm_sale_product ) {
foreach( $vpm_sale_product as $post_id ) {
$title = get_the_title( $post_id );
// if the post title is too long, truncate it and add "..." at the end
$title = ( mb_strlen( $title ) > 50 ) ? mb_substr( $title, 0, 49 ) . '...' : $title;
$html .= '<option value="' . $post_id . '" selected="selected">' . $title . '</option>';
}
}
$html .= '</select></p>';
echo $html;
//==========================================
}
//* Output the HTML for the metabox.
public function vpm_featured_product_callback() {
global $post;
// Nonce field to validate form request came from current site
wp_nonce_field( basename( __FILE__ ), 'vpm_featured_product_nonce' );
$html = '';
// always array because we have added [] to our <select> name attribute
$feature_sale_options = get_option( 'feature_sale_option_name' ); // Array of All Options
$vpm_featured_product = $feature_sale_options['vpm_featured_product'];
$html .= '<p><select id="vpm_featured_product" name="vpm_featured_product[]" multiple="multiple" style="width:99%;max-width:25em;">';
if( $vpm_featured_product ) {
foreach( $vpm_featured_product as $post_id ) {
$title = get_the_title( $post_id );
// if the post title is too long, truncate it and add "..." at the end
$title = ( mb_strlen( $title ) > 50 ) ? mb_substr( $title, 0, 49 ) . '...' : $title;
$html .= '<option value="' . $post_id . '" selected="selected">' . $title . '</option>';
}
}
$html .= '</select></p>';
echo $html;
echo $vpm_featured_product;
//==========================================
?>
<script>
(function ($) {
'use strict';
$(function () {
//--------------------------------------------------------------------------
// multiple select with AJAX search
$('#vpm_featured_product,#vpm_sale_product').select2({
ajax: {
url: ajaxurl, // AJAX URL is predefined in WordPress admin
dataType: 'json',
delay: 250, // delay in ms while typing when to perform a AJAX search
data: function (params) {
return {
q: params.term, // search query
action: 'getproductsearch' // AJAX action for admin-ajax.php
};
},
processResults: function( data ) {
var options = [];
if ( data ) {
// data is the array of arrays, and each of them contains ID and the Label of the option
$.each( data, function( index, text ) { // do not forget that "index" is just auto incremented value
options.push( { id: text[0], text: text[1] } );
});
}
return {
results: options
};
},
cache: true
},
minimumInputLength: 3 // the minimum of symbols to input before perform a search
});
//----------------------------------------------------------------------------------------
});
})(jQuery);
</script>
<?php
}
}
if ( is_admin() )
$feature_sale = new FeatureSale();

Answer 1

The problem is that these select tags are not using the correct name value:
<select id="vpm_sale_product" name="vpm_sale_product[]"...>
<select id="vpm_featured_product" name="vpm_featured_product[]"...>
And the proper name values are: (based on your register_setting() call)
<select id="vpm_sale_product" name="feature_sale_option_name[vpm_sale_product][]"...>
<select id="vpm_featured_product" name="feature_sale_option_name[vpm_featured_product][]"...>
And although after correcting the above issue, the form data would be saved properly, the fifth parameter (i.e. the menu/page slug) passed to add_submenu_page() should match the fourth parameter passed to add_settings_section() and add_settings_field(), and also the one passed to do_settings_sections(). In your add_submenu_page() call, the menu/page slug is feature-sale, but with the other three functions, you set it to feature-sale-admin.
And using wp_nonce_field() is recommended, but in your case, it's not necessary since you're submitting to wp-admin/options.php. Unless of course, you want to check that prior to WordPress saving the options. But even so, I believe one nonce field is good. :)