MDL-42190 workshop: Add the ability to delete submissions

A new capability is introduced to control this, granted to teacher/admin
roles by default: mod/workshop:deletesubmissions.  Additionally, students
can delete their own submissions if they are currently able to edit them.

mod/workshop/db/access.php

@@ -233,4 +233,15 @@ $capabilities = array(
             'manager' => CAP_ALLOW
         )
     ),
+
+    // Ability to delete other users' submissions.
+    'mod/workshop:deletesubmissions' => array(
+        'captype' => 'write',
+        'contextlevel' => CONTEXT_MODULE,
+        'archetypes' => array(
+            'teacher' => CAP_ALLOW,
+            'editingteacher' => CAP_ALLOW,
+            'manager' => CAP_ALLOW
+        )
+    ),
 );

mod/workshop/lang/en/workshop.php

@@ -92,6 +92,7 @@ $string['daystoday'] = 'today';
 $string['daystomorrow'] = 'tomorrow';
 $string['daysyesterday'] = 'yesterday';
 $string['deadlinesignored'] = 'Time restrictions do not apply to you';
+$string['deletesubmission'] = 'Delete submission';
 $string['editassessmentform'] = 'Edit assessment form';
 $string['editassessmentformstrategy'] = 'Edit assessment form ({$a})';
 $string['editingassessmentform'] = 'Editing assessment form';
@@ -255,6 +256,8 @@ $string['submission'] = 'Submission';
 $string['submissionattachment'] = 'Attachment';
 $string['submissionby'] = 'Submission by {$a}';
 $string['submissioncontent'] = 'Submission content';
+$string['submissiondeleteconfirm'] = 'Are you sure you want to delete the following submission?';
+$string['submissiondeleteconfirmteacher'] = 'This will also delete any assessments associated with this submission, which may affect the following students\' grades:';
 $string['submissionend'] = 'Submissions deadline';
 $string['submissionendbeforestart'] = 'Submissions deadline can not be specified before the open for submissions date';
 $string['submissionendevent'] = '{$a} (submissions deadline)';
@@ -316,6 +319,7 @@ $string['withoutsubmission'] = 'Reviewer without own submission';
 $string['workshop:addinstance'] = 'Add a new workshop';
 $string['workshop:allocate'] = 'Allocate submissions for review';
 $string['workshop:editdimensions'] = 'Edit assessment forms';
+$string['workshop:deletesubmissions'] = 'Delete submissions';
 $string['workshop:ignoredeadlines'] = 'Ignore time restrictions';
 $string['workshop:manageexamples'] = 'Manage example submissions';
 $string['workshopname'] = 'Workshop name';

mod/workshop/submission.php

@@ -27,13 +27,15 @@ require_once(dirname(dirname(dirname(__FILE__))).'/config.php');
 require_once(dirname(__FILE__).'/locallib.php');
 require_once($CFG->dirroot . '/repository/lib.php');
 
-$cmid   = required_param('cmid', PARAM_INT);            // course module id
-$id     = optional_param('id', 0, PARAM_INT);           // submission id
-$edit   = optional_param('edit', false, PARAM_BOOL);    // open for editing?
-$assess = optional_param('assess', false, PARAM_BOOL);  // instant assessment required
+$cmid       = required_param('cmid', PARAM_INT);            // course module id
+$id         = optional_param('id', 0, PARAM_INT);           // submission id
+$edit       = optional_param('edit', false, PARAM_BOOL);    // open for editing?
+$assess     = optional_param('assess', false, PARAM_BOOL);  // instant assessment required
+$delete     = optional_param('delete', false, PARAM_BOOL);  // example removal requested
+$confirm    = optional_param('confirm', false, PARAM_BOOL); // example removal request confirmed
 
-$cm     = get_coursemodule_from_id('workshop', $cmid, 0, false, MUST_EXIST);
-$course = $DB->get_record('course', array('id' => $cm->course), '*', MUST_EXIST);
+$cm         = get_coursemodule_from_id('workshop', $cmid, 0, false, MUST_EXIST);
+$course     = $DB->get_record('course', array('id' => $cm->course), '*', MUST_EXIST);
 
 require_login($course, false, $cm);
 if (isguestuser()) {
@@ -85,9 +87,11 @@ $cansubmit      = has_capability('mod/workshop:submit', $workshop->context);
 $canallocate    = has_capability('mod/workshop:allocate', $workshop->context);
 $canpublish     = has_capability('mod/workshop:publishsubmissions', $workshop->context);
 $canoverride    = (($workshop->phase == workshop::PHASE_EVALUATION) and has_capability('mod/workshop:overridegrades', $workshop->context));
+$candeleteall   = has_capability('mod/workshop:deletesubmissions', $workshop->context);
 $userassessment = $workshop->get_assessment_of_submission_by_user($submission->id, $USER->id);
 $isreviewer     = !empty($userassessment);
 $editable       = ($cansubmit and $ownsubmission);
+$deletable      = $candeleteall;
 $ispublished    = ($workshop->phase == workshop::PHASE_CLOSED
                     and $submission->published == 1
                     and has_capability('mod/workshop:viewpublishedsubmissions', $workshop->context));
@@ -127,6 +131,21 @@ if ($editable and $workshop->useexamples and $workshop->examplesmode == workshop
 }
 $edit = ($editable and $edit);
 
+if (!$candeleteall and $ownsubmission and $editable) {
+    // Only allow the student to delete their own submission if it's still editable and hasn't been assessed.
+    if (count($workshop->get_assessments_of_submission($submission->id)) > 0) {
+        $deletable = false;
+    } else {
+        $deletable = true;
+    }
+}
+
+if ($submission->id and $delete and $confirm and $deletable) {
+    require_sesskey();
+    $workshop->delete_submission($submission);
+    redirect($workshop->view_url());
+}
+
 $seenaspublished = false; // is the submission seen as a published submission?
 
 if ($submission->id and ($ownsubmission or $canviewall or $isreviewer)) {
@@ -313,6 +332,31 @@ if ($edit) {
     die();
 }
 
+// Confirm deletion (if requested).
+if ($deletable and $delete) {
+    $prompt = get_string('submissiondeleteconfirm', 'workshop');
+    if ($candeleteall) {
+        $assessments = $workshop->get_assessments_of_submission($submission->id);
+        if (count($assessments) > 0) {
+            $prompt = html_writer::tag('p', $prompt);
+            $prompt .= html_writer::tag('p', get_string('submissiondeleteconfirmteacher', 'workshop'));
+            $affected = '';
+            $fields = get_all_user_name_fields(true);
+            $reviewers = array();
+            foreach ($assessments as $assessment) {
+                if (!in_array($assessment->reviewerid, $reviewers)) {
+                    $reviewers[] = $assessment->reviewerid;
+                    $names = $DB->get_record('user', array('id' => $assessment->reviewerid), $fields);
+                    $affected .= html_writer::tag('li', fullname($names));
+                }
+            }
+            $prompt .= html_writer::tag('ul', $affected);
+        }
+    }
+    echo $output->confirm($prompt,
+            new moodle_url($PAGE->url, array('delete' => 1, 'confirm' => 1)), $workshop->view_url());
+}
+
 // else display the submission
 
 if ($submission->id) {
@@ -337,6 +381,11 @@ if ($editable) {
     echo $output->single_button($btnurl, $btntxt, 'get');
 }
 
+if ($submission->id and $deletable) {
+    $url = new moodle_url($PAGE->url, array('delete' => 1));
+    echo $output->single_button($url, get_string('deletesubmission', 'workshop'), 'get');
+}
+
 if ($submission->id and !$edit and !$isreviewer and $canallocate and $workshop->assessing_allowed($USER->id)) {
     $url = new moodle_url($PAGE->url, array('assess' => 1));
     echo $output->single_button($url, get_string('assess', 'workshop'), 'post');

mod/workshop/version.php

@@ -24,7 +24,7 @@
 
 defined('MOODLE_INTERNAL') || die();
 
-$plugin->version   = 2015111600;        // The current module version (YYYYMMDDXX)
+$plugin->version   = 2016012100;        // The current module version (YYYYMMDDXX)
 $plugin->requires  = 2015111000;        // Requires this Moodle version.
 $plugin->component = 'mod_workshop';
 $plugin->cron      = 60;                // Give as a chance every minute.