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MAGPIERSS RECIPES: Cooking with Corbies |
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"Four and twenty blackbirds baked in a pie." |
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1. LIMIT THE NUMBER OF HEADLINES(AKA ITEMS) RETURNED. |
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PROBLEM: |
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You want to display the 10 (or 3) most recent headlines, but the RSS feed |
contains 15. |
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SOLUTION: |
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$num_items = 10; |
$rss = fetch_rss($url); |
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$items = array_slice($rss->items, 0, $num_items); |
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DISCUSSION: |
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Rather then trying to limit the number of items Magpie parses, a much simpler, |
and more flexible approach is to take a "slice" of the array of items. And |
array_slice() is smart enough to do the right thing if the feed has less items |
then $num_items. |
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See: http://www.php.net/array_slice |
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2. DISPLAY A CUSTOM ERROR MESSAGE IF SOMETHING GOES WRONG |
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PROBLEM: |
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You don't want Magpie's error messages showing up if something goes wrong. |
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SOLUTION: |
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# Magpie throws USER_WARNINGS only |
# so you can cloak these, by only showing ERRORs |
error_reporting(E_ERROR); |
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# check the return value of fetch_rss() |
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$rss = fetch_rss($url); |
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if ( $rss ) { |
...display rss feed... |
} |
else { |
echo "An error occured! " . |
"Consider donating more $$$ for restoration of services." . |
"<br>Error Message: " . magpie_error(); |
} |
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DISCUSSION: |
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MagpieRSS triggers a warning in a number of circumstances. The 2 most common |
circumstances are: if the specified RSS file isn't properly formed (usually |
because it includes illegal HTML), or if Magpie can't download the remote RSS |
file, and there is no cached version. |
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If you don't want your users to see these warnings change your error_reporting |
settings to only display ERRORs. Another option is to turn off display_error, |
so that WARNINGs, and NOTICEs still go to the error_log but not to the webpages. |
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You can do this with: |
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ini_set('display_errors', 0); |
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See: http://www.php.net/error_reporting, |
http://www.php.net/ini_set, |
http://www.php.net/manual/en/ref.errorfunc.php |
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3. GENERATE A NEW RSS FEED |
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PROBLEM: |
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Create an RSS feed for other people to use. |
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SOLUTION: |
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Use Useful Inc's RSSWriter (http://usefulinc.com/rss/rsswriter/) |
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DISCUSSION: |
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An example of turning a Magpie parsed RSS object back into an RSS file is forth |
coming. In the meantime RSSWriter has great documentation. |
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4. DISPLAY HEADLINES MORE RECENT THEN X DATE |
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PROBLEM: |
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You only want to display headlines that were published on, or after a certain |
date. |
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SOLUTION: |
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require 'rss_utils.inc'; |
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# get all headlines published today |
$today = getdate(); |
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# today, 12AM |
$date = mktime(0,0,0,$today['mon'], $today['mday'], $today['year']); |
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$rss = fetch_rss($url); |
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foreach ( $rss->items as $item ) { |
$published = parse_w3cdtf($item['dc']['date']); |
if ( $published >= $date ) { |
echo "Title: " . $item['title']; |
echo "Published: " . date("h:i:s A", $published); |
echo "<p>"; |
} |
} |
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DISCUSSION: |
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This recipe only works for RSS 1.0 feeds that include the <dc:date> field. |
(which is very good RSS style) |
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parse_w3cdtf is defined in rss_utils.inc, and parses RSS style dates into Unix |
epoch seconds. |
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See: http://www.php.net/manual/en/ref.datetime.php |