Calendar Function

[Anon]

I am currently building a community calendar that lists the date going down the left hand side in one column and community groups across the top -- kinda like a view all groups' events calendar. These events will span multiple dates from date x to date y. I would like to show the event span running down the calendar for each group. I can easily query the start and end date of each event sorted by group but am at a loss as to how to show the span graphically over the proper dates. Any help would be appreciated.

[van__]

for each event do either a colspan or rowspan in your table cell for the number of days for the event, and skip writing that day as a new table cell.

[Anon]

That'll totally work if there's only one event per day per group, if I'm not mistaken. But what if there are three events for one group (for example) starting on the same day but spanning different number of days? That makes it a bit tougher -- variable number of events per group.

[Anon]

Well, this should still be solvable. Imagine you have a table 'events' in your database;

event_id int,
start int,
end int,
description text

or whatever. 'start' and 'end' would be unix timestamps (mktime(), time(), date()) of the start/end times of the event.

(heck, this is going to be alot of queries.)

Just a theoretical example;

for ($x = 0; $x < $days_in_month; $x++) {
print '<td>';
$thisDayStart = mktime(make_timestamp_for_this_day_at_00:00);
$thisDayEnd = mktime(make_TS_for_this_day_at_23:59:59);

$res = mysql_query("select * from events where start > $thisDayStart and start < $thisDayEnd");
while ($matchEvent = mysql_fetch_array($res)) {
print "$matchEvent[event_id]";
}

print '</td>';
}

Theoretically, this should print the event_id for every event that takes place in the current day. Now, assuming the event_id is unique (wich it would have to be), use some technique to make a color value of it. (i.e. md5 it, sum the ascii value of all the chars, mod it by 255. This would be the first. Take this number, md5 it and mod by 255 to get the second etc etc. Or something.). Then call a small php script that generates a 3x3 pixel image with this color and output it instead of the last print above.

Should (hopefully) show a unique 3x3 pixel image for each event each day it's present. Further down the page, show each image (sorted by event start date) and a small event description.

OR SOMETHING! 🙂

[Anon]

Dang! That's an interesting way of approaching it. I'll take a look at it, sounds like a great exercise. Thanks.

[Anon]

no problem,

drop me an e-mail if you make it work! (or if you need help for that matter) (since phpbuilder e-mail notification is officially dead)! :-)

[Anon]

So close! It works for dealing with multiple events per group no sweat. Now I just need to figure out how to take the span over days into account. My events table is setup just like that (event start and end entries). You can't just query by start date on every day of the month. An event might start on a certain day but span over multiple days. The query wouldn't recognize that. I can almost smell the solution. I'll get it soon.

[Anon]

Well, of course there is a solution for that as well. In the example I gave, the point was (but probably not the code) that you query on each day, and find all events that's active that certain day. So regardless of span, it will show if it's supposed to.

Of course, there are other ways to do this. Imagine,..

// should obviously be dynamic
$currentMonth = 5;
$days_in_month = 31;

$monthBegin = mktime(1st_day_at_00:00:01);
$monthEnd = mktime(last_day_at_23:59:59);

$res = mysql_query("select * from events where start >= $monthBegin AND start <= $monthEnd");

we now have all the events that start in the current month. We don't care when they end, because they should show up even if they begin last day and end 3rd next month.

$events = array();
while ($oneEvent = mysql_fetch_array($res)) {
$dayStart = date("d", $oneEvent[start]);

if (date("m", $oneEvent[end]) == $currentMonth) {
$dayEnd = date("d", $oneEvent[end]);
} else {
$dayEnd = $days_in_month;
// event spans into next month, wich doesn't show on calendar
}
for ($x = $dayStart; $x <= $dayEnd; $x++)
$events[$x] .= " $oneEvent[id]";
}
foreach ($events AS $key => $val)
$events[$key] = trim($val);

Now, theoretically, $events[1] will hold a list of all event ids active on day 1, $events[2] for day 2 etc etc. Separated by a blank, so explode(" ", $events[x]) to get an array, and do whatever you want to them.

So, when you draw your calendar, just check the $events[current_day] and make some colors, images, or whatever! Alot less queries and cleaner than my last suggestion 🙂

[Anon]

Now i see how the span of events was being addressed. Thanks!