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POWeb spider on prices
 

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  1. POWeb spider on prices
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    <p>I would like to compare certain products by price on a couple of websites. So I can create a price history for myself before buying a product. If the price stays stable, I usually order the product, if not I go and ask questions why the price keeps going up and down.</p> <p>I wanted to program a web-crawler for myself using PHP so this is done automatically as it would take allot of time when I do it manually.</p> <p>So I created a MySql database where I input all the URL's from all the products I want to follow. After that I use i simple script to output the prices:</p> <pre><code>&lt;?php @ini_set("output_buffering", "Off"); @ini_set('implicit_flush', 1); @ini_set('zlib.output_compression', 0); @ini_set('max_execution_time', 1200); $dbhost = 'localhost'; $dbuser = 'salesrep'; $dbpass = 'pas'; $dbname = "spider"; $dbtable = "price_compair"; $conn = mysql_connect($dbhost, $dbuser, $dbpass) or die('Error connecting to mysql'); $selected = mysql_select_db($dbname) or die(mysql_error()); $results = mysql_query("SELECT * FROM $dbtable"); mysql_close($conn); while ($row = mysql_fetch_array($results, MYSQL_ASSOC)) { echo "&lt;td&gt;" . $row['artikel'] . "&lt;/td&gt;"; if ($row['url_site1'] == "") { echo "&lt;td&gt;&amp;nbsp;&lt;/td&gt;"; } else { if (!$fp = fopen($row['url_tx3'], "r")) { return false; } $content = ""; while (!feof($fp)) { $content .= fgets($fp, 1024); } fclose($fp); preg_match_all("/\&amp;euro; (\d+\.\d+)/", $content, $pricesite1, PREG_SET_ORDER); $replace1 = array("&amp;euro; "); echo "&lt;td&gt;" . str_replace($replace1, "", $pricesite1[1][0]) . "&lt;/td&gt;"; } if ($row['url_site2'] == "") { echo "&lt;td&gt;&amp;nbsp;&lt;/td&gt;"; } else { if (!$fp = fopen($row['url_tx3shop'], "r")) { return false; } $content = ""; if (ob_get_level() == 0) ob_start(); while (!feof($fp)) { $content .= fgets($fp, 1024); } fclose($fp); preg_match_all("/\d+\.\d+\,\d+|(\d+\,\d+)/", $content, $pricesite2, PREG_SET_ORDER); $replace2 = array("€ ", "."); $out = str_replace(",", ".", str_replace($replace2, "", $pricesite2[1][0])); if ($out == "") { echo "&lt;td&gt;" . str_replace(",", ".", str_replace($replace2, "", $pricesite2[0][0])) . "&lt;/td&gt;"; } else { echo "&lt;td&gt;" . $out . "&lt;/td&gt;"; } } echo "&lt;/tr&gt;"; ob_flush(); flush(); } ?&gt; </code></pre> <p>The main problem I came across was that 1 website uses the € sign, the other one handles &euro; in the code, so finding the price is tricky. Also, the euro sign could be in front or behind the price. And to make it more difficult, there could be a recommended retail price before the actual price.</p> <p>My script works at the moment, but the code I use for the preg_match_all is far from perfect. Is there anyone the has an idea on how to build it up so it practically works perfect on any website?</p> <p>Also, is the fgets statement I use a correct way on building the spider?</p> <p>I know that there are comparison website out there that do this for me, but I find it to be a fun PHP project :)</p>
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    1. COGood lord, please indent your code.
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    2. CO"perfect on any website?" No.
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    3. COPHP might not be your best tool for this. [NoodleJS](http://noodlejs.com/) makes it easy for you to create rules in JSON format that can be loaded on a website-by-website basis, making it much easier to target the DOM with the price in it.
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