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| 3 | <title>Magie RSS Recipes: Simple PHP RSS How To</title>
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| 5 | body {
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| 6 | font-family:trebuchet MS, trebuchet, verdana, arial, sans-serif;
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| 7 | font-size: 11px;
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| 8 |
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| 9 | }
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| 10 |
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| 11 | pre { font-family: "Courier New", monospace;
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| 12 | padding: 1em;
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| 13 | margin: 0.2em 2.5em 0.2em 3em;
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| 14 | background-color: #efeff5;
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| 15 | border: 1px solid #cfcfcf;
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| 16 | white-space: pre;
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| 17 | }
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| 18 |
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| 19 | </style>
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| 20 | </head>
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| 21 | <body>
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| 22 | <p>
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| 23 | <h1>MagpieRSS Recipes: Cooking with Corbies</h1>
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| 24 |
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| 25 | <div align="center"><h3><em>"Four and twenty blackbirds baked in a
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| 26 | pie."</em></h3></div>
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| 27 | </p>
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| 28 | <p>
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| 29 | <ol>
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| 30 | <li><a href="#limit">Limit the Number of Headlines(aka Items) Returned</a></li>
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| 31 | <li><a href="#error_message">Display a Custom Error Message if Something Goes
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| 32 | Wrong</a></li>
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| 33 | <li><a href="#write_rss">Generate a New RSS Feed</a></li>
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| 34 | <li><a href="#by_date">Display Headlines More Recent then X Date</a></li>
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| 35 | <li><a href="#from_file">Parse a Local File Containing RSS</a></li>
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| 36 |
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| 37 | </ol>
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| 38 | </p>
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| 39 |
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| 40 | <a name="limit"></a><h2>1. Limit the Number of Headlines(aka Items) Returned.</h2>
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| 41 |
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| 42 | <h3>Problem:</h3>
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| 43 |
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| 44 | You want to display the 10 (or 3 or whatever) most recent headlines, but the RSS feed
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| 45 | contains 15.
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| 46 |
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| 47 | <h3>Solution:</h3>
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| 48 |
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| 49 | <pre>
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| 50 | $num_items = 10;
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| 51 | $rss = fetch_rss($url);
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| 52 |
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| 53 | $items = array_slice($rss->items, 0, $num_items);
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| 54 |
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| 55 | foreach ( $items as $item ) {
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| 56 | </pre>
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| 57 | <h3>Discussion:</h3>
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| 58 |
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| 59 | Rather then trying to limit the number of items Magpie parses, a much simpler,
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| 60 | and more flexible approach is to take a "slice" of the array of items. And
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| 61 | array_slice() is smart enough to do the right thing if the feed has less items
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| 62 | then $num_items.
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| 63 |
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| 64 | <h3>See:</h3> <a href="http://www.php.net/array_slice">http://www.php.net/array_slice</a>
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| 65 | </p>
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| 66 |
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| 67 | <a name="error_message"></a><h2>2. Display a Custom Error Message if Something Goes Wrong</h2>
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| 68 |
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| 69 | <h3>Problem:</h3>
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| 70 |
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| 71 | You don't want Magpie's error messages showing up if something goes wrong.
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| 72 |
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| 73 | <h3>Solution:</h3>
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| 74 | <pre>
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| 75 | # Magpie throws USER_WARNINGS only
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| 76 | # so you can cloak these, by only showing ERRORs
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| 77 | error_reporting(E_ERROR);
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| 78 |
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| 79 | # check the return value of fetch_rss()
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| 80 |
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| 81 | $rss = fetch_rss($url);
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| 82 |
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| 83 | if ( $rss ) {
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| 84 | ...display rss feed...
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| 85 | }
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| 86 | else {
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| 87 | echo "An error occured! " .
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| 88 | "Consider donating more $$$ for restoration of services." .
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| 89 | "<br>Error Message: " . magpie_error();
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| 90 | }
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| 91 | </pre>
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| 92 | <h3>Discussion:</h3>
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| 93 |
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| 94 | MagpieRSS triggers a warning in a number of circumstances. The 2 most common
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| 95 | circumstances are: if the specified RSS file isn't properly formed (usually
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| 96 | because it includes illegal HTML), or if Magpie can't download the remote RSS
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| 97 | file, and there is no cached version.
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| 98 |
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| 99 | If you don't want your users to see these warnings change your error_reporting
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| 100 | settings to only display ERRORs.<br />
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| 101 | Another option is to turn off display_error,
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| 102 | so that WARNINGs, and NOTICEs still go to the error_log but not to the webpages.
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| 103 |
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| 104 | You can do this with:
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| 105 |
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| 106 | <pre>
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| 107 | # you can also do this in your php.ini file
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| 108 | ini_set('display_errors', 0);
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| 109 | </pre>
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| 110 |
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| 111 | <h3>See:</h3>
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| 112 | <a
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| 113 | href="http://www.php.net/error_reporting">http://www.php.net/error_reporting</a>,<br
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| 114 | />
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| 115 | <a href="http://www.php.net/ini_set">http://www.php.net/ini_set</a>, <br />
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| 116 | <a
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| 117 | href="http://www.php.net/manual/en/ref.errorfunc.php">http://www.php.net/manual/en/ref.errorfunc.php</a><br
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| 118 | />
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| 119 |
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| 120 | <a name="write_rss"></a><h2>3. Generate a New RSS Feed</h2>
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| 121 |
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| 122 | <h3>Problem:</h3>
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| 123 |
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| 124 | Create an RSS feed for other people to use.
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| 125 |
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| 126 | <h3>Solution:</h3>
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| 127 |
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| 128 | Use Useful Inc's <a href="http://usefulinc.com/rss/rsswriter/">RSSWriter</a>.
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| 129 |
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| 130 | <h3>Discussion:</h3>
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| 131 |
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| 132 | An example of turning a Magpie parsed RSS object back into an RSS file is
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| 133 | forthcoming. In the meantime RSSWriter is well documented.
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| 134 |
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| 135 | <a name="by_date"></a><h2>4. Display Headlines More Recent then X Date</h2>
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| 136 |
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| 137 | <h3>Problem:</h3>
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| 138 |
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| 139 | You only want to display headlines that were published on, or after a certain
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| 140 | date.
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| 141 |
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| 142 |
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| 143 | <h3>Solution:</h3>
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| 144 | <pre>
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| 145 | require_once('rss_utils.inc');
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| 146 |
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| 147 | # get all headlines published today
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| 148 | $today = getdate();
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| 149 |
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| 150 | # today, 12AM
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| 151 | $date = mktime(0,0,0,$today['mon'], $today['mday'], $today['year']);
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| 152 |
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| 153 | $rss = fetch_rss($url);
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| 154 |
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| 155 | foreach ( $rss->items as $item ) {
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| 156 | $published = parse_w3cdtf($item['dc']['date']);
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| 157 | if ( $published >= $date ) {
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| 158 | echo "Title: " . $item['title'];
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| 159 | echo "Published: " . date("h:i:s A", $published);
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| 160 | echo "<p>";
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| 161 | }
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| 162 | }
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| 163 | </pre>
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| 164 | <h3>Discussion:</h3>
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| 165 |
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| 166 | This recipe only works for RSS 1.0 feeds that include the <dc:date> field.
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| 167 | (which is very good RSS style) <br />
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| 168 | <code>parse_w3cdtf()</code> is defined in
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| 169 | <code>rss_utils.inc</code>, and parses RSS style dates into Unix epoch
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| 170 | seconds.
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| 171 |
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| 172 | <h3>See: </h3>
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| 173 | <a
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| 174 | href="http://www.php.net/manual/en/ref.datetime.php">http://www.php.net/manual/en/ref.datetime.php</a>
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| 175 |
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| 176 | <a name="from_file"></a>
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| 177 | <h2>5. Parse a Local File Containing RSS</h2>
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| 178 | <h3>Problem:</h3>
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| 179 | MagpieRSS provides <code>fetch_rss()</code> which takes a URL and returns a
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| 180 | parsed RSS object, but what if you want to parse a file stored locally that
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| 181 | doesn't have a URL?
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| 182 |
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| 183 | <h3>Solution</h3>
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| 184 | <pre>
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| 185 | require_once('rss_parse.inc');
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| 186 |
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| 187 | $rss_file = 'some_rss_file.rdf';
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| 188 | $rss_string = read_file($rss_file);
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| 189 | $rss = new MagpieRSS( $rss_string );
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| 190 |
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| 191 | if ( $rss and !$rss->ERROR) {
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| 192 | ...display rss...
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| 193 | }
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| 194 | else {
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| 195 | echo "Error: " . $rss->ERROR;
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| 196 | }
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| 197 |
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| 198 | # efficiently read a file into a string
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| 199 | # in php >= 4.3.0 you can simply use file_get_contents()
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| 200 | #
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| 201 | function read_file($filename) {
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| 202 | $fh = fopen($filename, 'r') or die($php_errormsg);
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| 203 | $rss_string = fread($fh, filesize($filename) );
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| 204 | fclose($fh);
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| 205 | return $rss_string;
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| 206 | }
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| 207 | </pre>
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| 208 |
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| 209 | <h3>Discussion</h3>
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| 210 | Here we are using MagpieRSS's RSS parser directly without the convience wrapper
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| 211 | of <code>fetch_rss()</code>. We read the contents of the RSS file into a
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| 212 | string, and pass it to the parser constructor. Notice also that error handling
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| 213 | is subtly different.
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| 214 |
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| 215 | <h3>See: </h3>
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| 216 | <a
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| 217 | href="http://www.php.net/manual/en/ref.filesystem.php">http://www.php.net/manual/en/ref.filesystem.php</a>,<br
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| 218 | />
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| 219 | <a
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| 220 | href="http://www.php.net/manual/en/language.oop.php">http://www.php.net/manual/en/language.oop.php</a>
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| 221 |
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| 222 | <!--
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| 223 | <a name="link"></a><h2>#. Recipe</h2>
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| 224 | <h3>Problem:</h3>
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| 225 | Problem description
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| 226 | <h3>Solution</h3>
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| 227 | <pre>
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| 228 | code
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| 229 | </pre>
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| 230 | <h3>Discussion/h3>
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| 231 | Discuss code
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| 232 | <h3>See: </h3>
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| 233 | Documentation links:
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| 234 | -->
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| 235 |
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| 236 | </body>
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| 237 | </html>
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