ob submit action

piklist-form-example.php

<?php
/*
Title: Grouped Post
Method: post
Message: Grouped Post Created
Logged in: true
*/

piklist( 'field', array(
  'type'  => 'hidden'
  ,'scope' => 'post'
  ,'field' => 'post_type'
  ,'value' => 'grouped'
)
); 
piklist('field', array(
  'type' => 'text'
  ,'field' => 'post_title'
  ,'scope' => 'post'
  ,'required' => true
  ,'label' => esc_html__('Title','dummytheme')
  ,'attributes' => array(
    'wrapper_class' => 'post_title'
    ,'class' => 'regular-text form-control'
  )
));

$cover = '';
if( isset($_GET['_post']) && isset($_GET['_post']['ID']) ) {
  $post_id = $_GET['_post']['ID'];
  $cover = ff_get_post_thumbnail( $post_id );
}
piklist('field', array(
  'type' => 'text'
  ,'field' => 'cover'
  ,'scope' => 'post_meta'
  ,'label' => esc_html__('Cover Image','dummytheme')
  ,'value' => $cover
  ,'attributes' => array(
    'class' => 'regular-text input-upload-file upload-image form-control dashicons-camera'
  )
));

piklist('field', array(
  'type'        => 'hidden'
  ,'scope'       => 'post_meta'
  ,'field'       => '_thumbnail_id'
  ,'required' => true
  ,'label' => esc_html__('Thumbnail ID','dummytheme')
  ,'attributes' => array(
    'class' => 'hide input-upload-file-id'
  )
));

piklist('field', array(
	'type'        => 'select'
,'field'       => 'group_type'
,'scope'       => 'taxonomy'
,'label' => esc_html__('Type','dummytheme')
,'choices' => piklist(get_terms('group_type', array(
		'hide_empty' => false,
	)), array(
			'term_id',
			'name',
		)
	)
,'attributes' => array(
		'class' => 'regular-text form-control'
	//	,'multiple' => 'multiple' // Allow a select field to accept multiple selections
	)
));

piklist( 'field', array(
  'type'  => 'text'
  ,'scope' => 'post_meta'
  ,'required' => true
  ,'label' => esc_html__('post Ids','dummytheme')
  ,'field' => 'post_ids_key'
  ,'attributes' => array(
    'class' => 'regular-text form-control input-upload-file-id'
  )
));



piklist('field', array(
  'type'    => 'hidden'
  ,'scope'  => 'post'
  ,'field'  => 'post_status'
  ,'value'  => 'pending'
));

// Submit button
piklist('field', array(
	'type' => 'submit'
,'field' => 'submit'
,'value' => esc_html__('Submit','dummytheme')
,'attributes' => array(
  'class' => 'btn primary text-white'
)));



function on_submit_query($term_id) {
  $taxonomy = 'group_type';
	$args = array(
			'post_type' => 'post',
			'post_status' => 'publish',
			'posts_per_page' => '-1',
			'tax_query' => array(
				'relation' => 'AND',
				array(
					'taxonomy' => $taxonomy,
					'field' => 'term_id',
					'terms' => $term_id,
				),
			),
		);
		$query = new WP_Query($args);
		$posts = $query->posts;
		$post_id_array = wp_list_pluck($query->posts, 'ID');
    return ($post_id_array);
}