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

Course

Activity

User Profile

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