[[!template id=plugin name=comments author="[[Simon_McVittie|smcv]]"]]
[[!tag type/useful]]
This plugin adds "blog-style" comments. The intention is that on a non-wiki site
(like a blog) you can lock all pages for admin-only access, then allow otherwise
unprivileged (or perhaps even anonymous) users to comment on posts.
Comments are saved as internal pages, so they can never be edited through the CGI,
only by direct committers. Currently, comments are always in [[ikiwiki/markdown]].
So, why do it this way, instead of using regular wiki pages in a
namespace, such as $page/comments/*? Then you could use [[plugins/lockedit]] to
limit editing of comments in more powerful ways. --[[Joey]]
Er... I suppose so. I'd assumed that these pages ought to only exist as inlines
rather than as individual pages (same reasoning as aggregated posts), though.
lockedit is actually somewhat insufficient, since check_canedit()
doesn't distinguish between creation and editing; I'd have to continue to use
some sort of odd hack to allow creation but not editing.
I also can't think of any circumstance where you'd want a user other than
admins (~= git committers) and possibly the commenter (who we can't check for
at the moment anyway, I don't think?) to be able to edit comments - I think
user expectations for something that looks like ordinary blog comments are
likely to include "others can't put words into my mouth".
My other objection to using a namespace is that I'm not particularly happy about
plugins consuming arbitrary pieces of the wiki namespace - /discussion is bad
enough already. Indeed, this very page would accidentally get matched by rules
aiming to control comment-posting... :-) --[[smcv]]
Thinking about it, perhaps one way to address this would be to have the suffix
(e.g. whether commenting on Sandbox creates sandbox/comment1 or sandbox/c1 or
what) be configurable by the wiki admin, in the same way that recentchanges has
recentchangespage => 'recentchanges'? I'd like to see fewer hard-coded page
names in general, really - it seems odd to me that shortcuts and smileys
hard-code the name of the page to look at. Perhaps I could add
discussionpage => 'discussion' too? --[[smcv]]
(I've now implemented this in my branch. --[[smcv]])
The best reason to keep the pages internal seems to me to be that you
don't want the overhead of every comment spawning its own wiki page.
The worst problem with it though is that you have to assume the pages
are mdwn (or default_pageext) and not support other formats. --[[Joey]]
Well, you could always have comment1._mdwn, comment2._creole etc. and
alter the htmlize logic so that the mdwn hook is called for both mdwn
and _mdwn (assuming this is not already the case). I'm not convinced
that multi-format comments are a killer feature, though - part of the point
of this plugin, in my mind, is that it's less flexible than the full power
of ikiwiki and gives users fewer options. This could be construed
to be a feature, for people who don't care how flexible the technology is
and just want a simple way to leave a comment. The FormattingHelp page
assumes you're writing 100% Markdown in any case...
Internal pages do too many things, perhaps: they suppress generation of
HTML pages, they disable editing over the web, and they have a different
namespace of htmlize hooks. I think the first two of those are useful
for this plugin, and the last is harmless; you seem to think the first
is useful, and the other two are harmful. --[[smcv]]
By the way, I think that who can post comments should be controllable by
the existing plugins opendiscussion, anonok, signinedit, and lockedit. Allowing
posting comments w/o any login, while a nice capability, can lead to
spam problems. So, use check_canedit as at least a first-level check?
--[[Joey]]
This plugin already uses check_canedit, but that function doesn't have a concept
of different actions. The hack I use is that when a user comments on, say, sandbox,
I call check_canedit for the pseudo-page "sandbox[postcomment]". The
special postcomment(glob) [[ikiwiki/pagespec]] returns true if the page ends with
"[postcomment]" and the part before (e.g. sandbox) matches the glob. So, you can
have postcomment(blog/*) or something. (Perhaps instead of taking a glob, postcomment
should take a pagespec, so you can have postcomment(link(tags/commentable))?)
This is why anonok_pages => 'postcomment(*)' and locked_pages => '!postcomment(*)'
are necessary to allow anonymous and logged-in editing (respectively).
This is ugly - one alternative would be to add check_permission() that takes a
page and a verb (create, edit, rename, remove and maybe comment are the ones I
can think of so far), use that, and port the plugins you mentioned to use that
API too. This plugin could either call check_can("$page/comment1", 'create') or
call check_can($page, 'comment').
One odd effect of the code structure I've used is that we check for the ability to
create the page before we actually know what page name we're going to use - when
posting the comment I just increment a number until I reach an unused one - so
either the code needs restructuring, or the permission check for 'create' would
always be for 'comment1' and never 'comment123'. --[[smcv]]
Another possibility is to just check for permission to edit (e.g.) sandbox/comment1.
However, this makes the "comments can only be created, not edited" feature completely
reliant on the fact that internal pages can't be edited. Perhaps there should be a
editable_pages pagespec, defaulting to '*'?
When using this plugin, you should also enable [[htmlscrubber]] and either [[htmltidy]]
or [[htmlbalance]]. Directives are filtered out by default, to avoid commenters slowing
down the wiki by causing time-consuming processing. As long as the recommended plugins
are enabled, comment authorship should hopefully be unforgeable by CGI users.
I'm not sure that raw html should be a problem, as long as the
htmlsanitizer and htmlbalanced plugins are enabled. I can see filtering
out directives, as a special case. --[[Joey]]
Right, if I sanitize each post individually, with htmlscrubber and either htmltidy
or htmlbalance turned on, then there should be no way the user can forge a comment;
I was initially wary of allowing meta directives, but I think those are OK, as long
as the comment template puts the [[!meta author]] at the end. Disallowing
directives is more a way to avoid commenters causing expensive processing than
anything else, at this point.
I've rebased the plugin on master, made it sanitize individual posts' content
and removed the option to disallow raw HTML. Sanitizing individual posts before
they've been htmlized required me to preserve whitespace in the htmlbalance
plugin, so I did that. Alternatively, we could htmlize immediately and always
save out raw HTML? --[[smcv]]
There might be some use cases for other directives, such as img, in
comments.
I don't know if meta is "safe" (ie, guaranteed to be inexpensive and not
allow users to do annoying things) or if it will continue to be in the
future. Hard to predict really, all that can be said with certainty is
all directives will contine to be inexpensive and safe enough that it's
sensible to allow users to (ab)use them on open wikis.
--[[Joey]]
When comments have been enabled generally, you still need to mark which pages
can have comments, by including the \[[!comments]] directive in them. By default,
this directive expands to a "post a comment" link plus an \[[!inline]] with
the comments. [This requirement has now been removed --[[smcv]]]
I don't like this, because it's hard to explain to someone why they have
to insert this into every post to their blog. Seems that the model used
for discussion pages could work -- if comments are enabled, automatically
add the comment posting form and comments to the end of each page.
--[[Joey]]
I don't think I'd want comments on every page (particularly, not the
front page). Perhaps a pagespec in the setup file, where the default is "*"?
Then control freaks like me could use "link(tags/comments)" and tag pages
as allowing comments.
Yes, I think a pagespec is the way to go. --[[Joey]]
Implemented --[[smcv]]
The model used for discussion pages does require patching the existing
page template, which I was trying to avoid - I'm not convinced that having
every possible feature hard-coded there really scales (and obviously it's
rather annoying while this plugin is on a branch). --[[smcv]]
Using the template would allow customising the html around the comments
which seems like a good thing? --[[Joey]]
The [[!comments]] directive is already template-friendly - it expands to
the contents of the template comments_embed.tmpl, possibly with the
result of an [[!inline]] appended. I should change comments_embed.tmpl
so it uses a template variable INLINE for the inline result rather than
having the perl code concatenate it, which would allow a bit more
customization (whether the "post" link was before or after the inline).
Even if you want comments in page.tmpl, keeping the separate comments_embed.tmpl
and having a COMMENTS variable in page.tmpl might be the way forward,
since the smaller each templates is, the easier it will be for users
to maintain a patched set of templates. (I think so, anyway, based on what happens
with dpkg prompts in Debian packages with monolithic vs split
conffiles.) --[[smcv]]
I've switched my branch to use page.tmpl instead; see what you think? --[[smcv]]
The plugin adds a new [[ikiwiki/PageSpec]] match type, postcomment, for use
with anonok_pagespec from the [[plugins/anonok]] plugin or locked_pages from
the [[plugins/lockedit]] plugin. Typical usage would be something like:
locked_pages => "!postcomment(*)"
to allow non-admin users to comment on pages, but not edit anything. You can also do
anonok_pages => "postcomment(*)"
to allow anonymous comments (the IP address will be used as the "author").
This is still called postcomment, although I've renamed the rest of the plugin
to comments as suggested on #ikiwiki --[[smcv]]
There are some global options for the setup file:
- comments_shown_pagespec: pages where comments will be displayed inline, e.g.
blog/*
or */discussion.
- comments_open_pagespec: pages where new comments can be posted, e.g.
blog/* and created_after(close_old_comments) or */discussion
- comments_pagename: if this is e.g.
comment_ (the default), then comments on the
[[sandbox]] will be called something like sandbox/comment_12
- comments_allowdirectives: if true (default false), comments may contain IkiWiki
directives
- comments_commit: if true (default true), comments will be committed to the version
control system
This plugin aims to close the [[todo]] item "[[todo/supporting_comments_via_disussion_pages]]",
and is currently available from [[smcv]]'s git repository on git.pseudorandom.co.uk (it's the
postcomment branch). A demo wiki with the plugin enabled is running at
http://www.pseudorandom.co.uk/2008/ikiwiki/demo/.
Known issues:
- Needs code review
- The access control via postcomment() is rather strange
- There is some common code cargo-culted from other plugins (notably inline and editpage) which
should probably be shared
I haven't done a detailed code review, but I will say I'm pleased you
avoided re-implementing inline! --[[Joey]]
Wishlist:
- tbm would like anonymous people to be able to enter their name and possibly email
address
- smcv would like an indication of who you're posting as / the ability to log in
as someone else (even if anonymous comments are allowed, it'd be nice to be
able to choose to log in with a username or OpenID, like in Livejournal);
perhaps editpage needs this too
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