Anonymous Users

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Objective

To allow users to switch into an anonymous mode when using certain activities eg when posting to a forum, so that the user's real identity cannot be ascertained by other non-privileged users.

Possible Use Cases

  1. Activity: for example a forum may be switched into anonymous mode by teacher rendering all posts anonymous.
  2. User: a user may choose to participate in an activity anonymously. In this case the teacher would switch the activity into an optional mode. For example, the forum module, when posting to a forum in an optional anonymous mode, the student could choose at the time of posting whether the post should be anonymous;
  3. Role Play: a teacher may choose to run the whole course in an anonymous mode to allow students to role play. In this case the anonymous mode will be forced to "yes" in the course settings.

Settings

Global

Anon global.png

Course

Anon course.png

Activity

Anon activity.png

User Profile

Anon profile.png

Code Changes

Status definitions

define('ANONYMITY_ON', 2);
define('ANONYMITY_OPTIONAL', 1);
define('ANONYMITY_INHERIT', 0);
define('ANONYMITY_OFF', -1);
define('ANONYMITY_DISABLED', -9999);

Capabilities

'moodle/anonymity:viewrealname' => array(
    'riskbitmask' => RISK_PERSONAL,
    'captype' => 'read',
    'contextlevel' => CONTEXT_SYSTEM,
    'legacy' => array(
        'editingteacher' => CAP_ALLOW,
        'manager' => CAP_ALLOW
    )
)

DB Tables

New table: anonymity_context

  • Record the anonymity status in given contexts
field type description
id int(10) unsigned auto-increment
contextid int(10) unsigned id from the context table
status int(4) signed anonymity status

New table: anonymity_user_context

  • Record user aliases for a particular context
field type description
id int(10) unsigned auto-increment
userid int(10) unsigned id from the user table
contextid int(10) unsigned id from the context table
alias varchar(255) the user's alias for this given context

Code

The fullname function in lib/moodlelib.php will be changed to return an anonymous name if applicable. We can take advantage of the Navigation 2.0 changes which ensure each page is linked to a specific context (That is, $PAGE->context will always to set to something sensible.)

As the fullname function may be called many times on a single page, it is extremely important that we keep the function as efficient as possible. It is also important that we implement these changes in a way that works in most instances without changes to the calling code.

function fullname($user, $override=false, $anonymous=false)

where the user object may also contain an alias property. The $anonymous parameter will only be checked if the anonymity status for the current context is set to optional.

What we return depends on:

  • anonymity status for the current context
  • $anonymous parameter
  • existing user alias in the anonymity_user_context table
  • alias property in the passed $user object
  • moodle/anonymity:viewrealname permission for the current user
  • $CFG->anonymityuseraliases

So what do we return? The following table shows the possibilities for various scenarios

anonymity status
$anonymous
$CFG->anonymityuseraliases
anonymity_user_alias.alias
$user->alias
moodle/anonymity:viewrealname
return example
off N/A N/A N/A N/A N/A "Real Name"
optional true false N/A N/A true get_string('anonymous').
"(Real Name)"
optional true false N/A N/A false get_string('anonymous')
optional true true (not set) (not set) true get_string('anonymous').
"(Real Name)"
optional true true (not set) (not set) false get_string('anonymous')
optional true true (not set) "Fred Jones" true "Fred Jones (Real Name)
optional true true (not set) "Fred Jones" false "Fred Jones"
optional true true "Bob Smith" (not set) false Bob Smith
optional true true "Bob Smith" (not set) true "Bob Smith (Real Name)"
optional true true "Bob Smith" "Fred Jones" false "Fred Jones"
optional true true "Bob Smith" "Fred Jones" true "Fred Jones (Real Name)"
optional false N/A N/A N/A N/A "Real Name"
on N/A false N/A N/A true get_string('anonymous').
"(Real Name)"
on N/A false N/A N/A false get_string('anonymous')
on N/A true (not set) (not set) true get_string('anonymous').
"(Real Name)"
on N/A true (not set) (not set) false get_string('anonymous')
on N/A true (not set) "Fred Jones" true "Fred Jones (Real Name)
on N/A true (not set) "Fred Jones" false "Fred Jones"
on N/A true "Bob Smith" (not set) false Bob Smith
on N/A true "Bob Smith" (not set) true "Bob Smith (Real Name)"
on N/A true "Bob Smith" "Fred Jones" false "Fred Jones"
on N/A true "Bob Smith" "Fred Jones" true "Fred Jones (Real Name)"


See also

  • MDL-1071 Add a forum option to allow anonymous posting