New "Switch Role" functionality to replace the old "Student view".

It's not well-tested yet and probably doesn't quite work.  I will keep debugging this tonight from home.

course/view.php

@@ -15,6 +15,8 @@
     $section     = optional_param('section', 0, PARAM_INT);
     $move        = optional_param('move', 0, PARAM_INT);
     $marker      = optional_param('marker',-1 , PARAM_INT);
+    $switchrole  = optional_param('switchrole',-1, PARAM_INT);
+
 
 
     if (empty($id) && empty($name) && empty($idnumber)) {
@@ -35,8 +37,17 @@
         }
     }
 
+    if (!$context = get_context_instance(CONTEXT_COURSE, $course->id)) {
+        print_error('nocontext');
+    }
+
     require_login($course->id);
 
+    if ($switchrole > -1) {
+        role_switch($switchrole, $context);
+        require_login($course->id);
+    }
+
     //If course is hosted on an external server, redirect to corresponding
     //url with appropriate authentication attached as parameter 
     if (file_exists($CFG->dirroot .'/course/externservercourse.php')) {
@@ -48,6 +59,7 @@
         }
     }
 
+
     require_once($CFG->dirroot.'/calendar/lib.php');    /// This is after login because it needs $USER
 
     add_to_log($course->id, 'course', 'view', "view.php?id=$course->id", "$course->id");

lang/en_utf8/moodle.php

@@ -706,7 +706,6 @@
 $string['includeuserfiles'] = 'Include User Files';
 $string['info'] = 'Information';
 $string['institution'] = 'Institution';
-$string['instudentview'] = 'in student view';
 $string['invalidemail'] = 'Invalid email address';
 $string['invalidlogin'] = 'Invalid login, please try again';
 $string['ip_address'] = 'IP Address';
@@ -1274,13 +1273,13 @@
 $string['studentnotallowed'] = 'Sorry, but you can not enter this course as \'$a\'';
 $string['students'] = 'Students';
 $string['studentsandteachers'] = 'Students and teachers';
-$string['studentviewoff'] = 'Turn student view off';
-$string['studentviewon'] = 'Turn student view on';
 $string['subcategories'] = 'Sub-categories';
 $string['success'] = 'Success';
 $string['summary'] = 'Summary';
 $string['summaryof'] = 'Summary of $a';
 $string['supplyinfo'] = 'Please supply some information about yourself';
+$string['switchrolereturn'] = 'Return to my normal role';
+$string['switchroleto'] = 'Switch role to...';
 $string['tag'] = 'Tag';
 $string['tagmanagement'] = 'Add/delete tags ...';
 $string['tags'] = 'Tags';

lib/accesslib.php

@@ -2634,6 +2634,62 @@ function get_roles_on_exact_context($context) {
 
 }
 
+/* 
+ * Switches the current user to another role for the current session and only
+ * in the given context.  If roleid is not valid (eg 0) or the current user 
+ * doesn't have permissions to be switching roles then the user's session 
+ * is compltely reset to have their normal roles.
+ * @param integer $roleid
+ * @param object $context
+ * @return bool
+ */
+function role_switch($roleid, $context) {
+    global $USER;
+
+    global $db;
+
+/// If we can't use this or are already using it or no role was specified then bail completely and reset
+    if (empty($roleid) || !has_capability('moodle/role:switchroles', $context) 
+        || !empty($USER->switchrole)  || !confirm_sesskey()) {
+        load_user_capability();   // Reset all permissions to normal
+        unset($USER->switchrole);  // Delete old capabilities
+        return true;
+    }
+
+/// We're allowed to switch but can we switch to the specified role?  Use assignable roles to check.
+    if (!$roles = get_assignable_roles($context)) {
+        return false;
+    }
+
+    if (empty($roles[$roleid])) {   /// We can't switch to this particular role
+        return false;
+    }
+
+    if (!$sitecontext = get_context_instance(CONTEXT_SYSTEM, SITEID)) {
+        return false;
+    }
+
+/// We have a valid roleid that this user can switch to, so let's set up the session
+
+    $USER->switchrole = $roleid;     // So we know later what state we are in
+
+    unset($USER->capabilities[$context->id]);  // Delete old capabilities
+
+    if ($capabilities = get_records_select('role_capabilities', "roleid = $roleid AND contextid = $sitecontext->id")) {
+        foreach ($capabilities as $capability) {
+            $USER->capabilities[$context->id][$capability->capability] = $capability->permission;
+        }
+    }
+
+/// Add some capabilities we are really going to always need, even if the role doesn't have them!
+
+    $USER->capabilities[$context->id]['moodle/course:view'] = CAP_ALLOW;
+
+    return true;
+
+}
+
+
 // get any role that has an override on exact context
 function get_roles_with_override_on_context($context) {
 
@@ -2668,4 +2724,5 @@ function get_users_from_role_on_context($role, $context) {
                             WHERE contextid = $context->id
                                   AND roleid = $role->id");  
 }
-?>
+
+?>

lib/pagelib.php

@@ -402,7 +402,7 @@ function print_header($title, $morebreadcrumbs = NULL) {
 
         // The "Editing On" button will be appearing only in the "main" course screen
         // (i.e., no breadcrumbs other than the default one added inside this function)
-        $buttons = update_course_icon($this->courserecord->id );
+        $buttons = switchroles_form($this->courserecord->id) . update_course_icon($this->courserecord->id );
         $buttons = empty($morebreadcrumbs) ? $buttons : ' ';
 
         print_header($title, $this->courserecord->fullname, $crumbtext,

lib/weblib.php

@@ -3712,6 +3712,46 @@ function update_course_icon($courseid) {
     }
 }
 
+/**
+ * Returns a little popup menu for switching roles
+ *
+ * @uses $CFG
+ * @uses $USER
+ * @param int $courseid The course  to update by id as found in 'course' table
+ * @return string
+ */
+function switchroles_form($courseid) {
+
+    global $CFG, $USER;
+
+
+    if (!$context = get_context_instance(CONTEXT_COURSE, $courseid)) {
+        return '';
+    }
+
+    if (has_capability('moodle/role:switchroles', $context)) {
+        if (empty($USER->switchrole)) {   // Print a menu
+            if (!$roles = get_assignable_roles($context)) {
+                return '';   // Nothing to show!
+            }
+
+            return popup_form($CFG->wwwroot.'/course/view.php?id='.$courseid.'&sesskey='.sesskey().'&switchrole=', 
+                              $roles, 'switchrole', '', get_string('switchroleto'), 'switchrole', '', true);
+
+        } else {  // Just a button to return to normal
+            $options = array();
+            $options['id'] = $courseid;
+            $options['sesskey'] = sesskey();
+            $options['switchrole'] = 0;
+
+            return print_single_button($CFG->wwwroot.'/course/view.php', $options,  
+                                       get_string('switchrolereturn'), 'post', '_self', true);
+        }
+    }
+
+    return '';
+}
+
 
 /**
  * Returns a turn edit on/off button for course in a self contained form.
@@ -5284,4 +5324,4 @@ function debugging($message='', $level=E_NOTICE) {
 }
 
 // vim:autoindent:expandtab:shiftwidth=4:tabstop=4:tw=140:
-?>
+?>