Comment Plugin

Comment Plugin lets users quickly post comments to a page without an edit/preview/save cycle.

Related topics: CommentPluginTemplates, CommentPluginExamples


Inserts an edit box into the page that allows users to type in and save comments. Comments can be made
  • in different formats (as defined by a template),
  • in both forward and reverse chronological order,
  • signed or unsigned, dated or undated (as defined by a template),
  • in other topics, or other positions within the current topic.

Supports the definition of custom templates for prompts and for formatting what is placed into topics.

Supports custom access controls, allowing you to use it to add content to topics where the commenting user doesn't have CHANGE permissions.

Uses Javascript (if available) to ensure feedback is as rapid as possible.


Write %COMMENT{attributes}% anywhere in a topic.


  • The following standard attributes are recognized
    Name Description Default
    type This is the name of the template to use for this comment. Comment templates are defined in a Foswiki template - see Customisation, below. If this attribute is not defined, the type is whatever is defined by COMMENTPLUGIN_DEFAULT_TYPE preference setting. below
    default Default text to put into the prompt.  
    target Name of the topic to add the comment to the current topic
    mode For compatibility with older versions only, synonymous with type  
    nonotify Set to "on" to disable change notification for target topics off
    noform Set to "on" to disable the automatic form that is generated around your comment prompt if you don't provide a FORM template. See CommentPluginExamples:noform for an example. off
    nopost Set to "on" to disable insertion of the posted text into the topic. off
    remove Set to "on" to remove the comment prompt after the first time it is clicked. off
    button Button label text Add comment

(See also additional attributes)

Positioning the comment

%COMMENT supports several ways to specify where a comment should be inserted in the target topic. This is referred to as the location of the comment.

Location relative to %COMMENT tag

The default location is the %COMMENT tag itself. For example:
will add comments in the current topic, directly below the %COMMENT tag.

Location relative to an anchor

The target attribute may specify a web, and may also specify an anchor within the target topic; for example,
%COMMENT{type="above" target="%USERSWEB%.PersonalRemarks#InsertHere"}%
This uses a standard in-topic anchor as the insertion location. See EditingShorthand for more about Foswiki anchors.

Default templates

Templates are used to define the "comment style" i.e. how comments appear in the page. The default is to add comments in "Blog like" style using bulleted lists, with the most recent comment at the top, but many other styles are available such as tables or Wiki thread mode comments. It is easy to define your own customer styles as well.

A set of default comment templates are shipped with the plugin - see also CommentPluginTemplates:
Template type Description
top Comments, signed and dated (server time), added at top of the topic (the anchor is ignored)
bottom Comments, signed and dated (server time), added at end of the target topic (the anchor is ignored)
above Comments, signed and dated (server time), added immediately before the target anchor, or the %COMMENT if no anchor is specified
bulletabove Comments, signed and dated (server time), bullet point added immediately before the target anchor, or the %COMMENT if no anchor is specified (inputsize="20" can be used to set the input length)
below Comments, signed and dated (server time), added immediately below the target anchor, or the %COMMENT if no anchor is specified
after Comments, signed and dated (server time), added added before the comment box, after the last comment
belowthreadmode Comments, signed and dated, added recurse after comment box
threadmode Wiki thread mode comment, signed and dated (server time)
tableprepend Comments, signed and dated (server time), formatted as an HTML table row, added below the anchor (which must be in an HTML <table>)
tableappend Comments, signed and dated (server time), formatted as an HTML table row, added above the anchor (which must be in an HTML <table>)
action Action added to action table directly above comment box (see Plugin Installation Instructions below for important notes)
table Tablerows adding on end
toctalk Talk using TOC adding on end
bookmark Create a list of annotated bookmarks
return Post to a different topic and return

Your local installation may add more template types as well - see Customization, below.


Customization of the comment plugin requires
  • familiarity with HTML forms
  • some familiarity with the Skin Templates.

To define a comment type, you have to provide at least two simple template definitions in the template file; one for the prompt box, and one for the generated output. If we have a template type "mytype", these are named PROMPT:mytype and OUTPUT:mytype respectively. See comments.tmpl in the templates directory for examples.

The plugin picks up these template definitions from a standard template file, templates/comments.tmpl. This allows different templates to be defined for different Foswiki skins.

Defining custom templates

By default, templates/comments.tmpl includes the topic CommentPluginTemplate, which contains all the shipped standard templates and in turn includes System.UserCommentsTemplate that can include non-standard customizations.

This allows for several levels of customization:
  1. To override all default templates, everywhere, change comments.tmpl to include a different topic (this customization will be lost next time you upgrade, though).
  2. To add site-wide local template customizations, add them to UserCommentsTemplate (create if it does not exist yet). You can redefine the standard templates here if you want, and your definitions will override the standard definitions.
  3. To override templates on a web-by-web basis, add a topic UserCommentsTemplate to the web (this will replace System.UserCommentsTemplate)
  4. To override templates for a specific skin, add them to System.UserComments<Skin>Template (where <Skin> is the name of the skin with the first letter capitalized, e.g. Pattern)

You can also define a comment template in a topic, by passing the topic location with templatetopic. For example:

   button="Add comment"

templatetopic accepts topic or web.topic syntax. See an example in CommentPluginExamples:templatetopic.

ALERT! Templates are picked up by following the standard rules for locating template files. Note that you can use %TMPL:INCLUDE to include other files of templates.

Customization example

Provide both a PROMPT and an OUTPUT definition:


Call your custom comment with:


The PROMPT template

The PROMPT template defines the contents of an HTML form that is used to capture the comment. This form invokes the comment generator when submitted. Parameters to the comment generator are defined using standard HTML input fields, such as input, textarea and select. The user enters values for these parameters, and these are then available when the OUTPUT template is expanded, in the form of %URLPARAM%s.

The FORM template

The FORM template can optionally be provided if you want to explicitly define the form (the <form> and </form> tHTML ags) that wraps around the PROMPT template. If you don't define a FORM=template, one is automatically generated for you (unless the =noform="on" parameter is given).

Providing attribute values

If an attribute is given to the %COMMENT tag that is not one of the standard attributes, then that attribute is taken as the name of a parameter to be expanded in the PROMPT template. Expressions in the template of the form %param|default% (e.g. %rows|3%, %button|Push me%) are expanded to the values given in the %COMMENT. For example, if the PROMPT template 'example' contains:
<textarea rows="%rows|3%" cols="%cols|50%" value="%tval|Rubbish%">
and the %COMMENT tag is:
%COMMENT{type="example" cols="75"}%
then the template will be expanded as
<textarea rows="3" cols="75" value="Rubbish">

Special macros

As well as support for all the usual macros in templates, the following special macros are supported in the PROMPT definition:
Macro Description
%DISABLED% Set to 'disabled' when you cannot comment (e.g. in preview mode).
%MESSAGE% The text specified by default. This may be overridden by a helpful message when the prompt is DISABLED.

Within a FORM definition, the body of the prompt is expanded to replace the %COMMENTPROMPT% macro.

EXPERT Note that when a comment is saved, the rest script is invoked on the target topic, with a number of parameters provided by the comment form. Normally the CommentPlugin will provide these fields in the form, but experts can also provide the fields themselves in order to get finer control over what is submitted, or you might want to define your own HTML forms that do comment submission. The parameters that the CommentPlugin recognises are as follows:
CGI parameter Description
comment_action Must be save to get the CommentPlugin to perform
comment_type Type of the OUTPUT template
comment_index Zero-based index of the %COMMENT in the source topic. Used to place a post relative to an existing %COMMENT.
comment_anchor Anchor taken from the target spec
comment_nonotify As passed to %COMMENT
comment_remove Zero-based index of a %COMMENT to remove from the target topic
comment_nopost As passed to %COMMENT
comment_templatetopic As passed to %COMMENT
comment_target Alternate save topic as passed to %COMMENT
Note that comment_anchor overrides comment_index. Example, shows an "I Approve" button that adds your approval signature to the end of the topic:
<form method="post" action="%SCRIPTURL{restauth}%/CommentPlugin/comment" >
<input type="submit" value="I Approve" />
<input type="hidden" name="topic" value="%WEB%/%TOPIC%" />
<input type="hidden" name="redirectto" value="%WEB%/%TOPIC%" />
<input type="hidden" name="comment_action" value="save" />
<input type="hidden" name="comment_type" value="bottom" />
<input type="hidden" name="comment" value="I Approve" />

Customisation example with custom form template

ALERT! This method has critical differences from the version shipped with Foswiki 1.1.4! (Identified by ALERT!)
Write a custom form in a topic.
  • ALERT! In the form, the action must be %SCRIPTURL{"rest"}%/CommentPlugin/comment. The save script used in previous versions will not work.
  • ALERT! In the form, the topic must be set to a valid, existing Web.Topic. topic is validated by the rest script which will reject the request if invalid.
  • ALERT! In the form, if the target topic will be provided by user input, use the comment_target input field to identify the target, otherwise it defaults to topic setting. comment_target is more flexible and can omit the Web part.
  • In the form set the location of the prompt with %COMMENTPROMPT%; the prompt will be positioned here.
  • In %COMMENT use parameter noform="on"
  • In %COMMENT use parameter templatetopic to point to the topic with the form template

Example form:
<form method="post" action="%SCRIPTURL{rest}%/CommentPlugin/comment" enctype="application/x-www-form-urlencoded" name="examplecomment" id="examplecomment">
<input type="hidden" name="topic"  value="%BASEWEB%/%BASETOPIC%" /> 
<input type="hidden" name="redirectto" value="%BASEWEB%.%BASETOPIC%" />

Example comment:
   button="Add comment"

The OUTPUT template

The OUTPUT template defines the format for the text that actually gets embedded into the topic. All the usual macros are available in the PROMPT definition, but note that a subset of macros are expanded when the comment is inserted in the text, so time, date and username will refer to the time and date when the comment was made, and the user who made it.

The expanded variables are:

All other Macros are inserted into the topic un-expanded and are expanded by standard rendering when the topic containing the comment is viewed.

In addition to Macros, there is one "token" expanded during output. $encodeguest will be set to "off" when the commenting user is logged in, and set to "entity" for anonymous comments. This is used in combination with the %URLPARAM% macro. Any user input from untrusted users should be entity encoded. For example:
%TMPL:DEF{outputoneliner}%   * %URLPARAM{"comment" encode="$encodeguest"}% -- %WIKIUSERNAME% - %GMTIME{"$day $month $year"}%%TMPL:END%

There are also four position tags that are used to indicate where the comment should be placed, relative to the location defined in the %COMMENT tag:

%POS:TOP% If present, comments will be inserted at the top of the topic i.e. before any other text
%POS:BOTTOM% If present, comments will be inserted at the end of the topic i.e. after all existing text
%POS:BEFORE% If present, comments will be inserted immediately before the %COMMENT% tag
%POS:AFTER% If present, comments will be inserted immediately after the %COMMENT% tag
Note that these position tags are obviously mutually exclusive. If you define more than one, the result is undefined. If none is present, the default is taken from the plugin setting DEFAULT_TYPE

%COMMENTPROMPT% Use with a custom form. If present, the comment prompt will be positioned here.

All the usual macros that can be used in a topic template can also be used in an OUTPUT template.

Custom access controls

Using configure, the plugin can be configured to use a different access control domain than the default CHANGE. This allows you to use the plugin to add content to topics where the commenting user does not have CHANGE (or even VIEW) access.

ALERT! Caution If you configure this plugin to use COMMENT permission instead of CHANGE, you should ensure that every web has the desired default permission by configuring ALLOWWEBCOMMENT or DENYWEBCOMMENT in every WebPreferences topic. You should also configure appropriate defaults in the _default Template web. If default permissions are not configured, then commenting will be permitted.


Two preference settings are recognised by the CommentPlugin:
Preference Default Description
%COMMENTPLUGIN_TEMPLATES% comments Name of template file in the 'templates' directory that contains the comment templates. The default 'comments.tmpl' automatically includes user templates from CommentPluginTemplate, which in turn includes UserCommentsTemplate.
%COMMENTPLUGIN_DEFAULT_TYPE% above Default template type
These can be set in SitePreferences, in each web's WebPreferences, or in individual topics.


Installation Instructions

You do not need to install anything in the browser to use this extension. The following instructions are for the administrator who installs the extension on the server.

Open configure, and open the "Extensions" section. "Extensions Operation and Maintenance" Tab -> "Install, Update or Remove extensions" Tab. Click the "Search for Extensions" button. Enter part of the extension name or description and press search. Select the desired extension(s) and click install. If an extension is already installed, it will not show up in the search results.

You can also install from the shell by running the extension installer as the web server user: (Be sure to run as the webserver user, not as root!)
cd /path/to/foswiki
perl tools/extension_installer <NameOfExtension> install

If you have any problems, or if the extension isn't available in configure, then you can still install manually from the command-line. See for more help.

Note that if you want to use the action template then you must also:
  1. Install the Foswiki:Extensions/ActionTrackerPlugin;
  2. Put the CommentPlugin before the ActionTrackerPlugin in the {PluginsOrder} configuration option (in configure)

Upgrade Instructions

This plugin has been significantly changed from the 10 April 2011 version shipped with Foswiki 1.1.4.
  • The plugin uses a rest handler to update topics. By default this script does not require authentication, and can now permit anonymous commenting. Examine the ( Security and Authentication tab, Login sub-tab ) configuration {AuthScripts} setting, and the scripts requiring authentication in the Apache configuration.
  • The plugin no longer processes %COMMENT macros during save. If you have developed any forms using the noform and templatetopic examples they must be revised.


Change History:  
2.94 (13 Oct 2020) Foswikitask:Item14941: only load comment.js and comment.css on pages where it is required
2.93 (22 Jan 2018) Foswikitask:Item14554: remove link to unused domain.
Foswikitask:Item14605: Unescaped brace in Regular Expression, Perl 5.27.8.
2.92 (21 Jan 2017) Foswikitask:Item14009: Comment plugin does not properly identify location to insert comment when specified as an anchor.
2.91 (08 Apr 2016) Foswikitask:Item14022: Update links to https. Released with Foswiki 2.1.1.
2.9 (03 Feb 2016) Foswikitask:Item13854: Set ALLOWTOPICVIEW = "*" on Comment Template. Requires compatibility patch on Foswiki 1.x or Foswiki 1.1.10.
2.8 (15 Nov 2015) Foswikitask:Item13852: Warn that COMMENT ACLs should be configured if enabled. Also suppress guest session warning on Foswiki 1.1.
2.7 (29 Sep 2015) Foswikitask:Item13576: Disable fields during submit, then clear input fields after comment is posted.
Foswikitask:Item13764: Entity encode any comments by guest users.
2.6 (24 Jul 2015) Foswikitask:Item13502: Expand macros when returning an inline Ajax response.
2.5 (24 Jun 2015) Foswikitask:Item13474: Unicode fix
2.4 (14 Jun 2015) Foswikitask:Item13423: Perl 5.20 deprecations
Foswikitask:Item13345: CGI deprecations
Foswikitask:Item13287: Regular expression fixes
Foswikitask:Item13125: CGI parm calling changes
2.3 (18 Dec 2014) Foswikitask:Item12855: Core extensions should require JQueryPlugin 6.00
Foswikitask:Item13125: CGI changes for multi-value parameters
Foswikitask:Item13096: incorrect handling of unauthorised response
Foswikitask:Item13105: Eliminate sort from tables in Macros
Foswikitask:Item13106: removed blockquote where possible
Foswikitask:Item13027: Most try..catch clauses were catching Error::Simple s/b Error
Foswikitask:Item11737: Change hardcoded Main to %USERSWEB% Replace Sandbox with %SANDBOXWEB%
Foswikitask:Item12900: Implement some session handling improvements
2.2 (26 Sep 2014) Foswikitask:Item12931: add a highlight to JS-added comments; fix no-JS comments
2.1 (25 Apr 2014) Foswikitask:Item10191: Recoded REST as a proper JQuery plugin, with correctly formatted insertions. Note that the old location parameter has been removed, as it never worked properly, could cause damage to topics, and could not work with client comments. If you were using it, apologies, but it had to go. Correct use of validation and authentication. Ready for 2.0.
2.0.3 (22 Feb 2012) Foswikitask:Item11448 - Implement {GuestCanComment}. If enabled, guests can comment on topics that they can not edit.
2.0.2 (30 Jan 2012) 12887 Foswikitask:Item11447 - "noform" examples not working - add comment_target parameter.
2.0.1 (15 Jan 2012) Foswikitask:Item11443 - better handling if target topic or web do not exist.
10 Apr 2011 Foswikitask:Item10263 - remove wrap="soft" to make templates validate.
19 Nov 2010 Foswikitask:Item10050 - CommentPlugin prompt must not add newlines that prevent COMMENT inside TML tables
21 Oct 2010 Foswikitask:Item3499 - support COMMENT (and other) ACL preferences
Foswikitask:Item9592 - added AJAX example
Foswikitask:Item9601 - Prevent uprev of topic for every comment
Foswikitask:Item4423 - Spreadsheet calculations do not execute within comment templates
Foswikitask:Item9568 (and others) - Redesigned core. Change commonTagsHandler to registered COMMENT macro, convert to REST handler instead of save script with beforeSaveHandler
Foswikitask:Item5897 - if COMMENT target topic is missing, it should be created.
21 Oct 2010 Foswikitask:Item9857 - Restored the CommentPluginTemplate to how it was before. All the changes done to make it look nice causes many errors. Never again add newlines, never again add trailing \ on existing templates. It does not always work.
31 Jul 2010 Foswikitask:Item9415 - Documentation updates
27 May 2010 Moved example topic CommentPluginExamples to Sandbox web.
24 Feb 2010 Foswikitask:Item8611 - block comments resulting from calls to saveTopic from within an afterSaveHandler
12 Sep 2009 Foswikitask:Item8269 - Targeting anchors broken by Item727 is fixed.
04 Jun 2009 Foswikitask:Item1668 - The action template used with ActionTrackerPlugin now uses new syntax ending with %ENDACTION. This makes each action item appear on a new line. Additionally new lines are now correctly saved as html br tags and not as html encoded br tag
Foswikitask:Item1640 - Templates shipped with the plugin no longer encodes the user date entered when the date is saved so that it is possible for the user to use macros.
15 Jan 2008 Foswikitask:Item727 - data loss issue when missing anchor or location
13 Jan 2009 Foswikitask:Item736 - Make CommentPlugin aware of CompareRevisionsAddOn bin script.
16 Dec 2008 Foswiki version
06 Mar 2002 initial commit
Topic revision: r1 - 28 Mar 2022, UnknownUser
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