execute_task.php

<?php
    // This file is part of Moodle - http://moodle.org/
    //
    // Moodle is free software: you can redistribute it and/or modify
    // it under the terms of the GNU General Public License as published by
    // the Free Software Foundation, either version 3 of the License, or
    // (at your option) any later version.
    //
    // Moodle is distributed in the hope that it will be useful,
    // but WITHOUT ANY WARRANTY; without even the implied warranty of
    // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    // GNU General Public License for more details.
    //
    // You should have received a copy of the GNU General Public License
    // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

    /**
     * block_sentimentanalysis
     *
     * @author      Kara Beason <beasonke@appstate.edu>
     * @copyright   (c) 2019 Appalachian State Universtiy, Boone, NC
     * @license     GNU General Public License version 3
     * @package     block_sentimentanalysis
     */

    require_once('../../config.php');
    require_once(__DIR__ . '/lib.php');
    require_once(__DIR__ . '/classes/task/block_sentimentanalysis_task.php');

    use block_sentimentanalysis\task\block_sentimentanalysis_task;
    use \core\task\manager;

    defined('MOODLE_INTERNAL') || die();

    // We pass/fetch the block instance id
    $id = required_param('id', PARAM_INT);

    // Get the instance record using the block id
    $instancerec = $DB->get_record('block_instances', array('id' => $id));
    if (!$instancerec) {
        // No instance, no service
        throw new moodle_exception(get_string('invalidblockinstance', 'error', 'sentimentanalysis'));
    }

    $block = block_instance("sentimentanalysis", $instancerec);
    // Block instance rec leads to parent (course) context
    $coursecontext = context::instance_by_id($block->instance->parentcontextid);

    // Now I got the course id in the instanceid member. If anytihing goes wrong
    // want to go back to the course view.
    $PAGE->set_url('/course/view.php', array('id' => $coursecontext->instanceid));

    // Know which course we're in, so can authorize the user
    require_login($coursecontext->instanceid);
    // Check current user's capabilities.
    require_capability('moodle/course:manageactivities', $coursecontext);

    // If assignment list has not been configured, nothing to run.
    if (!$block->config) {
        redirect($PAGE->url, get_string("noconfigprompt", "block_sentimentanalysis"));
    }

    // Config is deserialized from text column, assignments in
    // array, create the ad hoc task and supply the needed ids
    $task = new block_sentimentanalysis_task();
    $task->set_userid($USER->id);
    $task->set_custom_data($block->config->assignments);
    // Queue it, then back to the course.
    manager::queue_adhoc_task($task);

    //Adding message to redirect until/unless I can figure out how to display it in the block upon clicking the execute button.
    redirect($PAGE->url, get_string("submitprompt", "block_sentimentanalysis"));