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<h2>Calendar</h2>
part of the <a href="index.html">ArsDigita Community System</a>
by <a href="http://photo.net/philg/">Philip Greenspun</a>
<hr>
<ul>
<li>User-accessible directory: <a href="/calendar/">/calendar/</a>
<li>Site administrator directory: <a href="/admin/calendar/">/admin/calendar/</a>
<li>Group administrator directory: <a href="/calendar/admin">/calendar/admin</a>
<li>data model : <a href="/doc/sql/display-sql.tcl?url=/doc/sql/calendar.sql">/doc/sql/calendar.sql</a>
<li>Tcl procs: /tcl/calendar-defs.tcl
</ul>
<h3>The Big Idea</h3>
A site like photo.net might want to offer a calendar of upcoming
events. This has nothing to do with displaying things in a
wall-calendar style format, as provided by <a
href="calendar-widget.html">the calendar widget</a>. In fact, a
calendar of upcoming events is usually better presented as a list.
<p>
What distinguishes /calendar from /news is that items may be categorized
and the display at a large site might be personalized to a user's
country, state, or zip code. Also, if there are too many items to
display comfortably, the non-expired events coming up soonest get
displayed.
<p>
See <a href="http://www.harpcolumn.com">www.harpcolumn.com</a> for a
good running example that distinguishes /news from /calendar.
<h3>Under the Hood</h3>
The data model is simple:
<blockquote>
<pre><code>
create sequence calendar_category_id_sequence start with 1 ;
create table calendar_categories (
category_id integer primary key,
-- if scope=public, this is the address book the whole system
-- if scope=group, this is the address book for a particular group
scope varchar(20) not null,
group_id references user_groups,
category varchar(100) not null,
enabled_p char(1) default 't' check(enabled_p in ('t','f')),
constraint calendar_category_scope_check check ((scope='group' and group_id is not null) or
(scope='public')),
constraint calendar_category_unique_check unique(scope, category, group_id)
);
create index calendar_categories_group_idx on calendar_categories ( group_id );
create sequence calendar_id_sequence start with 1;
create table calendar (
calendar_id integer primary key,
category_id not null references calendar_categories,
title varchar(100) not null,
body varchar(4000) not null,
-- is the body in HTML or plain text (the default)
html_p char(1) default 'f' check(html_p in ('t','f')),
start_date date not null, -- first day of the event
end_date date not null, -- last day of the event (same as start_date for single-day events)
expiration_date date not null, -- day to stop including the event in calendars, typically end_date
event_url varchar(200), -- URL to the event
event_email varchar(100), -- email address for the event
-- for events that have a geographical location
country_code references country_codes(iso),
-- within the US
usps_abbrev references states,
-- we only want five digits
zip_code varchar(10),
approved_p char(1) default 'f' check(approved_p in ('t','f')),
creation_date date not null,
creation_user not null references users(user_id),
creation_ip_address varchar(50) not null
);
</code></pre>
</blockquote>
Comments are handled by <a href="general-comments.html">the general comments facility</a>.
<h3>Related Modules</h3>
The <a href="news.html">/news module</a> is better for generation
announcements (e.g., press releases from companies).
<p>
The <a href="bboard.html">/bboard system</a> is better if you want to
support lively discussion and archive the exchanges.
<hr>
<a href="http://photo.net/philg/"><address>philg@mit.edu</address></a>
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