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<!--
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* Authors: Chad Berkley
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* Copyright: 2000 Regents of the University of California and the
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* National Center for Ecological Analysis and Synthesis
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* For Details: http://www.nceas.ucsb.edu/
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* Created: 2007 November 5
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* Version:
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* File Info: '$Id: pagedreturn.html 3780 2008-04-02 23:28:31Z daigle $'
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*
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*
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-->
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<HTML>
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<HEAD>
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<TITLE>Metacat</TITLE>
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<link rel="stylesheet" type="text/css" href="./default.css">
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</HEAD>
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<BODY>
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<table width="100%">
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<tr>
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<td class="tablehead" colspan="2"><p class="label">Paged Query Returns</p></td>
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<td class="tablehead" colspan="2" align="right">
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<a href="./spatial_option.html">Back</a> | <a href="./metacattour.html">Home</a> |
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<a href="./unimplem.html">Next</a>
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</td>
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</tr>
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</table>
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<p>Metacat allows results sets to be broken up into "pages" to aid in the loading
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of large result sets and to make the result sets more readable to users. This is
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facilitated by the addition of two variables to the parameter list. Pagesize
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indicates how many results should be returned for a given page. Pagestart
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indicates which page you are currently viewing. These parameters can be
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passed to Metacat when a query is submited. </p>
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<p>When a paged query is performed, the resultset of that query contains
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four extra fields. Pagestart and pagesize are contained in the xml resultset
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along with nextpage and previouspage. This allows the xslt tranformation to
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include navigational links in the rendered resultset. Here's an example
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xml resultset.</p>
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<pre>
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<resultset>
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<pagestart>1</pagestart>
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<pagesize>10</pagesize>
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<nextpage>2</nextpage>
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<previouspage>0</previouspage>
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<query>
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...
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</query>
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<document>...</document>
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<document>...</document>
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</resultset>
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</pre>
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<p>In the case of the resultset, pagestart will always indicate the page you
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are currently viewing.</p>
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<p>Here's an example of the rendered result.</p>
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<img src="images/pagedquery.jpg"/>
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<p>The links to the previous and next pages look like this.</p>
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<pre>
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<a href="metacat?action=query&operator=INTERSECT&enableediting=false&anyfield=actor&qformat=kepler&pagestart=0&pagesize=10">Previous Page</a>
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<a href="metacat?action=query&operator=INTERSECT&enableediting=false&anyfield=actor&qformat=kepler&pagestart=2&pagesize=10">Next Page</a>
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</pre>
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<p>The important bits of these links are the incremented pagestart parameters.
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The rendered page is on page 1 so the previous page is 0 and the next
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page is 2. By sequencing through the pages, the user can see the
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entire resultset. </p>
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<p>The Kepler skin in lib/style/skins/kepler is a good example of how to
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render the resultset with paged query returns. The XSLT uses the four extra
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fields in the resultset to render the next and previous links. This could
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also be used within a non-web application.
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</p>
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<br>
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<a href="./spatial_option.html">Back</a> | <a href="./metacattour.html">Home</a> |
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<a href="./unimplem.html">Next</a>
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</BODY>
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</HTML>
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