Wikipedia:Edit filter/Documentation

The extension defines a domain-specific language solely to write filter rules. Since the language is not Turing complete, it cannot replace bots for more complex tasks.

Significant content taken from mw:Extension:AbuseFilter/Rules format; see page history for attribution.

Variables
The edit filter captures the following data from edits. They are stored in the following variables. They can be manipulated and analyzed with various functions and operators. The data types are  (signed integer values),   (sequences of Unicode characters),   (true and false),   (signed rational numbers),   (non-associative arrays) and   (usually an uninitialized variable).

Note that some numerical variables may be defined as a string; to act based on these variables, you may need to cast them to an. For example, the variable  is a string; to extract the date, hour etc. you must cast it to an   first (e.g.  ).

"Pre-save transformed" means after the wikitext is evaluated before saving; i.e. with template substitution. The wikitext is taken from the latest version before page save. For example, the  of  is  ; the   is exactly  verbatim.

For an up-to-date list of variables, see the documentation on mediawiki.org.

Arithmetic
concatenates a string with a string or other data type.

Keywords

 * returns true if the left string matches the right string; this is distinct from  as the right string is treated as a glob pattern.
 * returns true if the right string contains the left string.  is its reverse, i.e. returns true if the left string contains the right string. Note: empty strings are not contained in, nor contain, any other string (not even the empty string itself).
 * returns true if the left string matches the regular expression pattern in the right string.  is   with case-insensitivity. The regex engine is PCRE with support for Unicode characters. Beware, as regex is potentially expensive for two reasons:
 * The time to run a regex with quantifiers can grow exponentially with the size of an edit because of PCRE's backtracking algorithm.
 * Calling each regex has a fixed overhead, so merging multiple regexes together would be wise.
 * and the ternary conditional operator.

Declaring new variables
You can declare new variables within a condition; their scope is lexical scoping limited to the condition they appear within.

Functions
For an up-to-date list of available functions see mw:Extension:AbuseFilter/Rules format.

Actions which can be assigned in response to filtered edits
If a user triggers a filter, the edit filter can apply any of the following sanctions based on the severity of the offense:
 * All actions triggering a filter are logged at a special page.
 * The user's action can be tagged for further review.
 * The user can be warned that their actions may be unconstructive.
 * The user's action may be disallowed.
 * The user's autoconfirmed status may be revoked (or delayed if the user doesn't hold it).

The following actions are currently not available on this wiki:
 * The user's account may be blocked from editing, along with all IP addresses used in the last 7 days.
 * The user's account may be removed from all privileged groups (such as sysop, bot, rollbacker).

Note: Individual sanctions can be disabled selectively. Any edit filter manager can restore autoconfirmed status in case of an error.

Condition limit
The condition limit is a limit imposed by the software on the total number of conditions that can be evaluated by the filters. It is arbitrarily fixed at 2,000. While the aim of this limit is to avoid performance issues, it should be noted that this isn't a good metric of how heavy a filter is: for instance, a filter using dozens of simple comparisons (and thus dozens of conditions) is much lighter than one using a single check on the  variable. See mw:Extension:AbuseFilter/Conditions and mw:Extension:AbuseFilter/Rules format for more details.

Monitoring
All edits triggering an action will produce a report at Special:AbuseLog. On this page, a brief log entry is entered. Users with the appropriate permissions may view the log summary. Users with certain higher permissions may view details on the log entry. This includes all information available to the filter when it ran, and may be useful for debugging purposes. Users with the highest level of log-viewing permissions may view private data about the action which caused the log event, such as the user's IP address. See the AbuseFilter documentation for more details on the permissions structure.

Sample abuse log entries

 * 06:43, 23 June 2008: Andrew (talk | contribs | block) triggered an abuse filter, making an edit on Main Page. Actions taken: warn,disallow; Filter description: Test Filter
 * 06:43, 23 June 2008: Andrew (talk | contribs | block) triggered an abuse filter, making an edit on Main Page. Actions taken: none; Filter description: Test Filter

Sample detailed abuse log entries

 * 06:43, 23 June 2008: Andrew (talk | contribs | block) triggered filter 1, making an edit on Main Page. Actions taken: warn,disallow; Filter description: Test Filter (details)
 * 06:43, 23 June 2008: Andrew (talk | contribs | block) triggered filter 2, making an edit on Main Page. Actions taken: none; Filter description: Test Filter (details)
 * 06:42, 23 June 2008: Andrew (talk | contribs | block) triggered filter 1, making an edit on Main Page. Actions taken: warn; Filter description: Test Filter (details)
 * 06:42, 23 June 2008: Andrew (talk | contribs | block) triggered filter 2, making an edit on Main Page. Actions taken: none; Filter description: Test Filter (details)
 * 06:22, 23 June 2008: Andrew (talk | contribs | block) triggered filter 1, making an edit on Main Page. Actions taken: warn,disallow; Filter description: Test Filter (details)
 * 06:22, 23 June 2008: Andrew (talk | contribs | block) triggered filter 2, making an edit on Main Page. Actions taken: none; Filter description: Test Filter (details)

The details link brings up a screen like that on the right.

Safeguards
To protect the wiki against poorly configured filters, a technical limit is imposed on the maximum percentage of actions that will trigger a given filter. Other technical limits are in the process of being written.

Notification
All notifications are based on the template.

Standard notifications shown to a user triggering a filter action:

Generic warning message is below. Admins are advised to use custom warnings.

Some existing filters and their warnings:

If a filter is set to warn and disallow, then a user clicking "Save page" will alternatively see that warning and standard disallowed message.