Save Selected Option in Meta Box - wordpress

Question

i am going to build my own theme
I try to add select to post_type meta box, but every update post my select not on selected option but show the first option (blank value)
here is my code
function mhs_data() {
global $post;
echo '<input type="hidden" name="eventmeta_noncename" id="eventmeta_noncename" value="' .
wp_create_nonce( plugin_basename(__FILE__) ) . '" />';
$nisn = get_post_meta($post->ID, '_nisn', true);
$rel = get_post_meta($post->ID, '_rel', true);
}
echo '<p>NISN</p>';
echo '<input type="text" name="_nisn" value="' . $nisn . '" class="widefat" />';
echo '<p>Relationship</p>'; ?>
<select name="_rel" id="_rel">
<option value="">Relationship</option>
<option value="Single" <?php selected( $rel, 'Single' ); ?>>Single</option>
<option value="Marry" <?php selected( $rel, 'Marry' ); ?>>Marry</option>
</select>
<?php
}
function mhs_data_meta($post_id, $post) {
if ( !wp_verify_nonce( $_POST['eventmeta_noncename'], plugin_basename(__FILE__) )) {
return $post->ID;
}
if ( !current_user_can( 'edit_post', $post->ID ))
return $post->ID;
$events_meta['_nisn'] = $_POST['_nisn'];
$events_meta['_rel'] = $_POST['_rel'];
foreach ($events_meta as $key => $value) {
if( $post->post_type == 'revision' ) return;
$value = implode(',', (array)$value);
if(get_post_meta($post->ID, $key, FALSE)) {
update_post_meta($post->ID, $key, $value);
} else {
add_post_meta($post->ID, $key, $value);
}
if(!$value) delete_post_meta($post->ID, $key);
}
}
add_action('save_post', 'mhs_data_meta', 1, 2);
Please help me to correct my code

Answer 1

Using Codestar Framework its very simple tu add metaboxes to your custom post, create configuration page, plugins, taxonomies and use the customizer if you prefer use it instead of a configuration page. see the documentation here for more information.
in your example, to add a select metabox shuld use a code similar to:
load the framework on your functions.php
require_once __DIR__ . '/'.$FRAMEWORK_PATH.'/cs-framework/cs-framework.php';
edit the cs-framekork.php configuration file to active only the features you need:
defined('CS_ACTIVE_FRAMEWORK') or define('CS_ACTIVE_FRAMEWORK', false); // if you need it for plugin or configuration page
defined('CS_ACTIVE_METABOX') or define('CS_ACTIVE_METABOX', true); // if you only need it for metabox
defined('CS_ACTIVE_TAXONOMY') or define('CS_ACTIVE_TAXONOMY', false);
defined('CS_ACTIVE_SHORTCODE') or define('CS_ACTIVE_SHORTCODE', false);
defined('CS_ACTIVE_CUSTOMIZE') or define('CS_ACTIVE_CUSTOMIZE', false);
and then in your function.php or as I prefer on another file included in your function.php register your metabox
function register_this_metabox($options)
{
$options = array(); // this will clean the default cs-framework configuration
$options[] = array(
'id' => 'the_metabox',
'title' => 'Meta Box title',
'post_type' => 'post', // the post type where the metabox appears
'context' => 'side', // metabox position
'priority' => 'high',
'sections' => array( // metabox fields, see the documentation
array(
'name' => 'the_metabox_fields',
'fields' => array(
array(
'id' => 'the_metabox_select_field',
'type' => 'select',
'title' => 'Select Field',
'options' => array(
'opt1' => 'Option 1',
'opt2' => 'Option 2',
'opt3' => 'Option 3',
),
'default_option' => 'Select a option',
),
),
),
),
);
return $options;
}
add_filter('cs_metabox_options', 'register_this_metabox');
And now you only have to get the values in your theme:
$post_metabox = get_post_meta($post->ID, 'the_metabox', true);
$selected_option = $post_metabox['the_metabox_select_field']