Returns results of Wordpress Ninja Forms as AJAX friendly JSON ouput (for angular.js)

script.php

<?php
	$subs = ninja_forms_get_all_subs( 1 );
	$fields = ninja_forms_get_fields_by_form_id( 1 );

	$json_data = [];
	foreach ($subs as $sub_id => $sub) {
		$submission_data = array(); 
		$data = unserialize($sub['data']);
		$user_values = array();
		foreach ($data as $key => $value) {
			$user_values[$value['field_id']] = $value['user_value'];
		}

		foreach ( $fields as $field_id => $field ) {
			$user_value = $user_values[$field['id']];
			if ($user_value == '') { 
				continue;
			}

			$submission_data[] = array(
				"label" => $field['data']['label'],
				"value" => $user_value,
				"type" => $field['type']
			);
		}

		$json_data[] = array(
				"id" => $sub['id'],
				"items" => array_values($submission_data)
			);
			
		echo json_encode(array_values($json_data), JSON_PRETTY_PRINT);
	}
?>

Hello,

Can you please have the kindness and support a newbie to WP? Where would you add this code in WP?

Thank you,
FEY