ACF extension to select pages by specified page template only. Include file in functions.php

acf-page-by-template.php

<?php
function include_field_types_acf_pages_by_template( $version ) {
	include_once('acf-pages-by-template.php');
}
add_action('acf/include_field_types', 'include_field_types_acf_pages_by_template');

// exit if accessed directly
if( ! defined( 'ABSPATH' ) ) exit;

// check if class already exists
if( !class_exists('acf_field_page_by_template') ) :


class acf_field_page_by_template extends acf_field {


	/*
	*  __construct
	*
	*  This function will setup the field type data
	*
	*  @type	function
	*  @date	5/03/2014
	*  @since	5.0.0
	*
	*  @param	n/a
	*  @return	n/a
	*/

	function __construct() {

		$this->name = 'page_by_template';
		$this->label = __('Page by Template', 'acf-page_by_template');
		$this->category = 'relational';

		$this->defaults = array(
			'post_type'		=> 'page',
			'template'		=> array(),
			'allow_null' 	=> 0,
			'return_format'	=> 'object',
			'multiple'      => '',
			'ajax'          => '',
		);

    	parent::__construct();
	}

	/*
	*  render_field_settings()
	*
	*  Create extra settings for your field. These are visible when editing a field
	*
	*  @type	action
	*  @since	3.6
	*  @date	23/01/13
	*
	*  @param	$field (array) the $field being edited
	*  @return	n/a
	*/

	function render_field_settings( $field ) {

		// default_value
		acf_render_field_setting( $field, array(
			'label'			=> __('Page Template','acf'),
			'instructions'	=> '',
			'type'			=> 'select',
			'name'			=> 'template',
			'choices'		=> array_flip(get_page_templates()),
			'allow_null'	=> 1,
			'placeholder'	=> __("All page templates",'acf'),
		));

		// allow_null
		acf_render_field_setting( $field, array(
			'label'			=> __('Allow Null?','acf'),
			'instructions'	=> '',
			'type'			=> 'radio',
			'name'			=> 'allow_null',
			'choices'		=> array(
				1				=> __("Yes",'acf'),
				0				=> __("No",'acf'),
			),
			'layout'	=>	'horizontal',
		));

		// return_format
		acf_render_field_setting( $field, array(
			'label'			=> __('Return Format','acf'),
			'instructions'	=> '',
			'type'			=> 'radio',
			'name'			=> 'return_format',
			'choices'		=> array(
				'object'		=> __("Post Object",'acf'),
				'id'			=> __("Post ID",'acf'),
			),
			'layout'	=>	'horizontal',
		));

	}

	/*
	*  render_field()
	*
	*  Create the HTML interface for your field
	*
	*  @param	$field (array) the $field being rendered
	*
	*  @type	action
	*  @since	3.6
	*  @date	23/01/13
	*
	*  @param	$field (array) the $field being edited
	*  @return	n/a
	*/

	function render_field( $field ) {

		// Change Field into a select
		$field['type'] = 'select';
		$field['choices'] = array('' => 'Select a page');
		$field['ui'] = 1;


		// get posts
		$posts = acf_get_posts(array(
			'post__in'   => '',
			'post_type'  => $field['post_type'],
			'meta_query' => array(
				array(
					'key'   => '_wp_page_template',
					'value' => $field['template'],
				),
		    ),
		));

		// populate choices
		if( !empty($posts) ) {

			foreach( array_keys($posts) as $i ) {

				// vars
				$post = acf_extract_var( $posts, $i );

				// append to choices
				$field['choices'][ $post->ID ] = $post->post_title;

			}

		} else {
			$templates = array_flip(get_page_templates());
			$field['choices'] = array('' => "No pages found with template ".$templates[$field['template']]);
		}

		// render
		acf_render_field( $field );

	}

	/*
	*  input_admin_enqueue_scripts()
	*
	*  This action is called in the admin_enqueue_scripts action on the edit screen where your field is created.
	*  Use this action to add CSS + JavaScript to assist your render_field() action.
	*
	*  @type	action (admin_enqueue_scripts)
	*  @since	3.6
	*  @date	23/01/13
	*
	*  @param	n/a
	*  @return	n/a
	*/

	/*

	function input_admin_enqueue_scripts() {

		// vars
		$url = $this->settings['url'];
		$version = $this->settings['version'];


		// register & include JS
		wp_register_script( 'acf-input-page_by_template', "{$url}assets/js/input.js", array('acf-input'), $version );
		wp_enqueue_script('acf-input-page_by_template');


		// register & include CSS
		wp_register_style( 'acf-input-page_by_template', "{$url}assets/css/input.css", array('acf-input'), $version );
		wp_enqueue_style('acf-input-page_by_template');

	}

	*/


	/*
	*  input_admin_head()
	*
	*  This action is called in the admin_head action on the edit screen where your field is created.
	*  Use this action to add CSS and JavaScript to assist your render_field() action.
	*
	*  @type	action (admin_head)
	*  @since	3.6
	*  @date	23/01/13
	*
	*  @param	n/a
	*  @return	n/a
	*/

	/*

	function input_admin_head() {



	}

	*/


	/*
   	*  input_form_data()
   	*
   	*  This function is called once on the 'input' page between the head and footer
   	*  There are 2 situations where ACF did not load during the 'acf/input_admin_enqueue_scripts' and
   	*  'acf/input_admin_head' actions because ACF did not know it was going to be used. These situations are
   	*  seen on comments / user edit forms on the front end. This function will always be called, and includes
   	*  $args that related to the current screen such as $args['post_id']
   	*
   	*  @type	function
   	*  @date	6/03/2014
   	*  @since	5.0.0
   	*
   	*  @param	$args (array)
   	*  @return	n/a
   	*/

   	/*

   	function input_form_data( $args ) {



   	}

   	*/


	/*
	*  input_admin_footer()
	*
	*  This action is called in the admin_footer action on the edit screen where your field is created.
	*  Use this action to add CSS and JavaScript to assist your render_field() action.
	*
	*  @type	action (admin_footer)
	*  @since	3.6
	*  @date	23/01/13
	*
	*  @param	n/a
	*  @return	n/a
	*/

	/*

	function input_admin_footer() {



	}

	*/


	/*
	*  field_group_admin_enqueue_scripts()
	*
	*  This action is called in the admin_enqueue_scripts action on the edit screen where your field is edited.
	*  Use this action to add CSS + JavaScript to assist your render_field_options() action.
	*
	*  @type	action (admin_enqueue_scripts)
	*  @since	3.6
	*  @date	23/01/13
	*
	*  @param	n/a
	*  @return	n/a
	*/

	/*

	function field_group_admin_enqueue_scripts() {

	}

	*/


	/*
	*  field_group_admin_head()
	*
	*  This action is called in the admin_head action on the edit screen where your field is edited.
	*  Use this action to add CSS and JavaScript to assist your render_field_options() action.
	*
	*  @type	action (admin_head)
	*  @since	3.6
	*  @date	23/01/13
	*
	*  @param	n/a
	*  @return	n/a
	*/

	/*

	function field_group_admin_head() {

	}

	*/


	/*
	*  load_value()
	*
	*  This filter is applied to the $value after it is loaded from the db
	*
	*  @type	filter
	*  @since	3.6
	*  @date	23/01/13
	*
	*  @param	$value (mixed) the value found in the database
	*  @param	$post_id (mixed) the $post_id from which the value was loaded
	*  @param	$field (array) the field array holding all the field options
	*  @return	$value
	*/

	/*

	function load_value( $value, $post_id, $field ) {

		return $value;

	}

	*/


	/*
	*  update_value()
	*
	*  This filter is applied to the $value before it is saved in the db
	*
	*  @type	filter
	*  @since	3.6
	*  @date	23/01/13
	*
	*  @param	$value (mixed) the value found in the database
	*  @param	$post_id (mixed) the $post_id from which the value was loaded
	*  @param	$field (array) the field array holding all the field options
	*  @return	$value
	*/

	/*

	function update_value( $value, $post_id, $field ) {

		return $value;

	}

	*/


	/*
	*  format_value()
	*
	*  This filter is appied to the $value after it is loaded from the db and before it is returned to the template
	*
	*  @type	filter
	*  @since	3.6
	*  @date	23/01/13
	*
	*  @param	$value (mixed) the value which was loaded from the database
	*  @param	$post_id (mixed) the $post_id from which the value was loaded
	*  @param	$field (array) the field array holding all the field options
	*
	*  @return	$value (mixed) the modified value
	*/

	/*

	function format_value( $value, $post_id, $field ) {

		// bail early if no value
		if( empty($value) ) {

			return $value;

		}


		// apply setting
		if( $field['font_size'] > 12 ) {

			// format the value
			// $value = 'something';

		}


		// return
		return $value;
	}

	*/


	/*
	*  validate_value()
	*
	*  This filter is used to perform validation on the value prior to saving.
	*  All values are validated regardless of the field's required setting. This allows you to validate and return
	*  messages to the user if the value is not correct
	*
	*  @type	filter
	*  @date	11/02/2014
	*  @since	5.0.0
	*
	*  @param	$valid (boolean) validation status based on the value and the field's required setting
	*  @param	$value (mixed) the $_POST value
	*  @param	$field (array) the field array holding all the field options
	*  @param	$input (string) the corresponding input name for $_POST value
	*  @return	$valid
	*/

	/*

	function validate_value( $valid, $value, $field, $input ){

		// Basic usage
		if( $value < $field['custom_minimum_setting'] )
		{
			$valid = false;
		}


		// Advanced usage
		if( $value < $field['custom_minimum_setting'] )
		{
			$valid = __('The value is too little!','acf-page_by_template'),
		}


		// return
		return $valid;

	}

	*/


	/*
	*  delete_value()
	*
	*  This action is fired after a value has been deleted from the db.
	*  Please note that saving a blank value is treated as an update, not a delete
	*
	*  @type	action
	*  @date	6/03/2014
	*  @since	5.0.0
	*
	*  @param	$post_id (mixed) the $post_id from which the value was deleted
	*  @param	$key (string) the $meta_key which the value was deleted
	*  @return	n/a
	*/

	/*

	function delete_value( $post_id, $key ) {



	}

	*/


	/*
	*  load_field()
	*
	*  This filter is applied to the $field after it is loaded from the database
	*
	*  @type	filter
	*  @date	23/01/2013
	*  @since	3.6.0
	*
	*  @param	$field (array) the field array holding all the field options
	*  @return	$field
	*/

	/*

	function load_field( $field ) {

		return $field;

	}

	*/


	/*
	*  update_field()
	*
	*  This filter is applied to the $field before it is saved to the database
	*
	*  @type	filter
	*  @date	23/01/2013
	*  @since	3.6.0
	*
	*  @param	$field (array) the field array holding all the field options
	*  @return	$field
	*/

	/*

	function update_field( $field ) {

		return $field;

	}

	*/


	/*
	*  delete_field()
	*
	*  This action is fired after a field is deleted from the database
	*
	*  @type	action
	*  @date	11/02/2014
	*  @since	5.0.0
	*
	*  @param	$field (array) the field array holding all the field options
	*  @return	n/a
	*/

	/*

	function delete_field( $field ) {



	}

	*/
}

// initialize
new acf_field_page_by_template();

// class_exists check
endif;