repo_zf1/documentation/manual/en/module_specs/Zend_Paginator-Usage.xml

<?xml version="1.0" encoding="UTF-8"?>
<!-- Reviewed: no -->
<sect1 id="zend.paginator.usage">
    <title>Usage</title>

    <sect2 id="zend.paginator.usage.paginating">
        <title>Paginating data collections</title>

        <para>
            In order to paginate items into pages, <classname>Zend_Paginator</classname>
            must have a generic way of accessing that data. For that reason,
            all data access takes place through data source adapters. Several
            adapters ship with Zend Framework by default:
        </para>

        <table id="zend.paginator.usage.paginating.adapters">
            <title>Adapters for Zend_Paginator</title>

            <tgroup cols="2">
                <thead>
                    <row>
                        <entry>Adapter</entry>
                        <entry>Description</entry>
                    </row>
                </thead>
                <tbody>
                    <row>
                        <entry>Array</entry>
                        <entry>Use a PHP array</entry>
                    </row>
                    <row>
                        <entry>DbSelect</entry>
                        <entry>
                            Use a <link linkend="zend.db.select"><classname>Zend_Db_Select</classname></link>
                            instance, which will return an array
                        </entry>
                    </row>
                    <row>
                        <entry>DbTableSelect</entry>
                        <entry>
                            Use a <link linkend="zend.db.table.fetch-all"><classname>Zend_Db_Table_Select</classname></link>
                            instance, which will return an instance of
                            <classname>Zend_Db_Table_Rowset_Abstract</classname>.
                            This provides additional information about the
                            result set, such as column names.
                        </entry>
                    </row>
                    <row>
                        <entry>Iterator</entry>
                        <entry>
                            Use an <ulink url="http://www.php.net/~helly/php/ext/spl/interfaceIterator.html"><code>Iterator</code></ulink>
                            instance
                        </entry>
                    </row>
                    <row>
                        <entry>Null</entry>
                        <entry>
                            Do not use <classname>Zend_Paginator</classname> to manage
                            data pagination. You can still take advantage of
                            the pagination control feature.
                        </entry>
                    </row>
                </tbody>
            </tgroup>
        </table>

        <note>
            <para>
                Instead of selecting every matching row of a given query, the
                DbSelect and DbTableSelect adapters retrieve only the smallest
                amount of data necessary for displaying the current page.
            </para>

            <para>
                Because of this, a second query is dynamically generated to
                determine the total number of matching rows. However, it is
                possible to directly supply a count or count query yourself.
                See the <code>setRowCount()</code> method in the DbSelect
                adapter for more information.
            </para>
        </note>

        <para>
            To create an instance of <classname>Zend_Paginator</classname>, you must
            supply an adapter to the constructor:
        </para>

        <para>
            <programlisting language="php"><![CDATA[
$paginator = new Zend_Paginator(new Zend_Paginator_Adapter_Array($array));
]]></programlisting>
        </para>

        <para>
            For convenience, you may take advantage of the static
            <code>factory()</code> method for the adapters packaged with Zend
            Framework:
        </para>

        <para>
            <programlisting language="php"><![CDATA[
$paginator = Zend_Paginator::factory($array);
]]></programlisting>
        </para>

        <note>
            <para>
                In the case of the Null adapter, in lieu of a data collection
                you must supply an item count to its constructor.
            </para>
        </note>

        <para>
            Although the instance is technically usable in this state, in your
            controller action you'll need to tell the paginator what page
            number the user requested. This allows him to advance through the
            paginated data.
        </para>

        <para>
            <programlisting language="php"><![CDATA[
$paginator->setCurrentPageNumber($page);
]]></programlisting>
        </para>

        <para>
            The simplest way to keep track of this value is through a URL.
            Although we recommend using a
            <classname>Zend_Controller_Router_Interface</classname>-compatible
            router to handle this, it is not a requirement.
        </para>

        <para>
            The following is an example route you might use in an INI
            configuration file:
        </para>

        <para>
            <programlisting language="php"><![CDATA[
routes.example.route = articles/:articleName/:page
routes.example.defaults.controller = articles
routes.example.defaults.action = view
routes.example.defaults.page = 1
routes.example.reqs.articleName = \w+
routes.example.reqs.page = \d+
]]></programlisting>
        </para>

        <para>
            With the above route (and using Zend Framework MVC components),
            you might set the current page number like this:
        </para>

        <para>
            <programlisting language="php"><![CDATA[
$paginator->setCurrentPageNumber($this->_getParam('page'));
]]></programlisting>
        </para>

        <para>
            There are other options available; see
            <link linkend="zend.paginator.configuration">Configuration</link>
            for more on them.
        </para>

        <para>
            Finally, you'll need to assign the paginator instance to your view.
            If you're using <classname>Zend_View</classname> with the ViewRenderer action
            helper, the following will work:
        </para>

        <para>
            <programlisting language="php"><![CDATA[
$this->view->paginator = $paginator;
]]></programlisting>
        </para>
    </sect2>
    
    <sect2 id="zend.paginator.usage.dbselect">
        <title>The DbSelect and DbTableSelect adapter</title>
        <para>
            The usage of most adapters is pretty straight-forward. However, the
            database adapters require a more detailed explanation. Contrary to popular
            believe, these adapters do NOT fetch all records from the database in order to count them.
            Instead, the adapters manipulates the original query to produce the corresponding
            COUNT query. Paginator then executes that COUNT query to get the number of rows.
            This does require an extra round-trip to the database, but this is many times
            faster than fetching an entire result set and using count(). Especially with
            large collections of data.
        </para>
        
        <para>
            The database adapters will try and build the most efficient query that will execute
            on pretty much all modern databases. However, depending on your database or even your
            own schema setup, there might be more efficient ways to get a rowcount. For this scenario
            the database adapters allow you to set a custom COUNT query. For example,
            if you keep track of the count of blog posts in a separate table, you could achieve a
            faster count query with the following setup:  
        </para>
        
        <programlisting language="php"><![CDATA[
$adapter = new Zend_Paginator_Adapter_DbSelect($db->select()->from('posts'));
$adapter->setRowCount(
    $db->select()->from('item_counts', array(Zend_Paginator_Adapter_DbSelect::ROW_COUNT_COLUMN => 'post_count')) 
)

$paginator = new Zend_Paginator($adapter);
]]></programlisting>
    
        <para>
            This approach will probably not give you a huge performance gain on
            small collections and/or simple select queries. However, with complex
            queries and large collections, a similar approach could give you a 
            significant performance boost.
        </para>
    </sect2>

    <sect2 id="zend.paginator.rendering">
        <title>Rendering pages with view scripts</title>

        <para>
            The view script is used to render the page items (if you're using
            <classname>Zend_Paginator</classname> to do so) and display the pagination
            control.
        </para>

        <para>
            Because <classname>Zend_Paginator</classname> implements the SPL interface
            <ulink url="http://www.php.net/~helly/php/ext/spl/interfaceIteratorAggregate.html"><code>IteratorAggregate</code></ulink>,
            looping over your items and displaying them is simple.
        </para>

        <para>
            <programlisting language="php"><![CDATA[
<html>
<body>
<h1>Example</h1>
<?php if (count($this->paginator)): ?>
<ul>
<?php foreach ($this->paginator as $item): ?>
  <li><?php echo $item; ?></li>
<?php endforeach; ?>
</ul>
<?php endif; ?>

<?php echo $this->paginationControl($this->paginator,
                             'Sliding',
                             'my_pagination_control.phtml'); ?>
</body>
</html>
]]></programlisting>
        </para>

        <para>
            Notice the view helper call near the end. PaginationControl
            accepts up to four parameters: the paginator instance, a scrolling
            style, a view partial, and an array of additional parameters.
        </para>

        <para>
            The second and third parameters are very important. Whereas the
            view partial is used to determine how the pagination control should
            <emphasis>look</emphasis>, the scrolling style is used to control
            how it should <emphasis>behave</emphasis>. Say the view partial is
            in the style of a search pagination control, like the one below:
        </para>

        <para>
            <inlinegraphic align="center" valign="middle"
                fileref="figures/zend.paginator.usage.rendering.control.png"
                format="PNG"/>
        </para>

        <para>
            What happens when the user clicks the "next" link a few times?
            Well, any number of things could happen. The current page number
            could stay in the middle as you click through (as it does on
            Yahoo!), or it could advance to the end of the page range and then
            appear again on the left when the user clicks "next" one more time.
            The page numbers might even expand and contract as the user
            advances (or "scrolls") through them (as they do on Google).
        </para>

        <para>
            There are four scrolling styles packaged with Zend Framework:
        </para>

        <table id="zend.paginator.usage.rendering.scrolling-styles">
            <title>Scrolling styles for Zend_Paginator</title>

            <tgroup cols="2">
                <thead>
                    <row>
                        <entry>Scrolling style</entry>
                        <entry>Description</entry>
                    </row>
                </thead>
                <tbody>
                    <row>
                        <entry>All</entry>
                        <entry>
                            Returns every page. This is useful for dropdown
                            menu pagination controls with relatively few
                            pages. In these cases, you want all pages
                            available to the user at once.
                        </entry>
                    </row>
                    <row>
                        <entry>Elastic</entry>
                        <entry>
                            A Google-like scrolling style that expands and
                            contracts as a user scrolls through the pages.
                        </entry>
                    </row>
                    <row>
                        <entry>Jumping</entry>
                        <entry>
                            As users scroll through, the page number advances
                            to the end of a given range, then starts again at
                            the beginning of the new range.
                        </entry>
                    </row>
                    <row>
                        <entry>Sliding</entry>
                        <entry>
                            A Yahoo!-like scrolling style that positions the
                            current page number in the center of the page
                            range, or as close as possible. This is the
                            default style.
                        </entry>
                    </row>
                </tbody>
            </tgroup>
        </table>

        <para>
            The fourth and final parameter is reserved for an optional
            associative array of additional variables that you want available
            in your view partial (available via <code>$this</code>). For
            instance, these values could include extra URL parameters for
            pagination links.
        </para>

        <para>
            By setting the default view partial, default
            scrolling style, and view instance, you can eliminate the calls to
            PaginationControl completely:
        </para>

        <para>
            <programlisting language="php"><![CDATA[
Zend_Paginator::setDefaultScrollingStyle('Sliding');
Zend_View_Helper_PaginationControl::setDefaultViewPartial(
    'my_pagination_control.phtml'
);
$paginator->setView($view);
]]></programlisting>
        </para>

        <para>
            When all of these values are set, you can render the pagination
            control inside your view script with a simple echo statement:
        </para>

        <para>
            <programlisting language="php"><![CDATA[
<?php echo $this->paginator; ?>
]]></programlisting>
        </para>

        <note>
            <para>
                Of course, it's possible to use <classname>Zend_Paginator</classname>
                with other template engines. For example, with Smarty you
                might do the following:
            </para>

            <para>
                <programlisting language="php"><![CDATA[
$smarty->assign('pages', $paginator->getPages());
]]></programlisting>
            </para>

            <para>
                You could then access paginator values from a template like so:
            </para>

            <para>
                <programlisting language="php"><![CDATA[
{$pages.pageCount}
]]></programlisting>
            </para>
        </note>

        <sect3 id="zend.paginator.usage.rendering.example-controls">
            <title>Example pagination controls</title>

            <para>
                The following example pagination controls will hopefully help
                you get started:
            </para>

            <para>
                Search pagination

                <programlisting language="php"><![CDATA[
<!--
See http://developer.yahoo.com/ypatterns/pattern.php?pattern=searchpagination
-->

<?php if ($this->pageCount): ?>
<div class="paginationControl">
<!-- Previous page link -->
<?php if (isset($this->previous)): ?>
  <a href="<?php echo $this->url(array('page' => $this->previous)); ?>">
    &lt; Previous
  </a> |
<?php else: ?>
  <span class="disabled">&lt; Previous</span> |
<?php endif; ?>

<!-- Numbered page links -->
<?php foreach ($this->pagesInRange as $page): ?>
  <?php if ($page != $this->current): ?>
    <a href="<?php echo $this->url(array('page' => $page)); ?>">
        <?php echo $page; ?>
    </a> |
  <?php else: ?>
    <?php echo $page; ?> |
  <?php endif; ?>
<?php endforeach; ?>

<!-- Next page link -->
<?php if (isset($this->next)): ?>
  <a href="<?php echo $this->url(array('page' => $this->next)); ?>">
    Next &gt;
  </a>
<?php else: ?>
  <span class="disabled">Next &gt;</span>
<?php endif; ?>
</div>
<?php endif; ?>
]]></programlisting>
            </para>

            <para>
                Item pagination

                <programlisting language="php"><![CDATA[
<!--
See http://developer.yahoo.com/ypatterns/pattern.php?pattern=itempagination
-->

<?php if ($this->pageCount): ?>
<div class="paginationControl">
<?php echo $this->firstItemNumber; ?> - <?php echo $this->lastItemNumber; ?>
of <?php echo $this->totalItemCount; ?>

<!-- First page link -->
<?php if (isset($this->previous)): ?>
  <a href="<?php echo $this->url(array('page' => $this->first)); ?>">
    First
  </a> |
<?php else: ?>
  <span class="disabled">First</span> |
<?php endif; ?>

<!-- Previous page link -->
<?php if (isset($this->previous)): ?>
  <a href="<?php echo $this->url(array('page' => $this->previous)); ?>">
    &lt; Previous
  </a> |
<?php else: ?>
  <span class="disabled">&lt; Previous</span> |
<?php endif; ?>

<!-- Next page link -->
<?php if (isset($this->next)): ?>
  <a href="<?php echo $this->url(array('page' => $this->next)); ?>">
    Next &gt;
  </a> |
<?php else: ?>
  <span class="disabled">Next &gt;</span> |
<?php endif; ?>

<!-- Last page link -->
<?php if (isset($this->next)): ?>
  <a href="<?php echo $this->url(array('page' => $this->last)); ?>">
    Last
  </a>
<?php else: ?>
  <span class="disabled">Last</span>
<?php endif; ?>

</div>
<?php endif; ?>
]]></programlisting>
            </para>

            <para>
                Dropdown pagination

                <programlisting language="php"><![CDATA[
<?php if ($this->pageCount): ?>
<select id="paginationControl" size="1">
<?php foreach ($this->pagesInRange as $page): ?>
  <?php $selected = ($page == $this->current) ? ' selected="selected"' : ''; ?>
  <option value="<?php
        echo $this->url(array('page' => $page));?>"<?php echo $selected ?>>
    <?php echo $page; ?>
  </option>
<?php endforeach; ?>
</select>
<?php endif; ?>

<script type="text/javascript"
     src="http://ajax.googleapis.com/ajax/libs/prototype/1.6.0.2/prototype.js">
</script>
<script type="text/javascript">
$('paginationControl').observe('change', function() {
    window.location = this.options[this.selectedIndex].value;
})
</script>
]]></programlisting>
            </para>
        </sect3>

        <sect3 id="zend.paginator.usage.rendering.properties">
            <title>Listing of properties</title>

            <para>
                The following options are available to pagination control
                view partials:
            </para>

            <table id="zend.paginator.usage.rendering.properties.table">
                <title>Properties available to view partials</title>

                <tgroup cols="3">
                    <thead>
                        <row>
                            <entry>Property</entry>
                            <entry>Type</entry>
                            <entry>Description</entry>
                        </row>
                    </thead>
                    <tbody>
                        <row>
                            <entry>first</entry>
                            <entry>integer</entry>
                            <entry>First page number (i.e., 1)</entry>
                        </row>
                        <row>
                            <entry>firstItemNumber</entry>
                            <entry>integer</entry>
                            <entry>
                                Absolute number of the first item on this page
                            </entry>
                        </row>
                        <row>
                            <entry>firstPageInRange</entry>
                            <entry>integer</entry>
                            <entry>
                                First page in the range returned by the
                                scrolling style
                            </entry>
                        </row>
                        <row>
                            <entry>current</entry>
                            <entry>integer</entry>
                            <entry>Current page number</entry>
                        </row>
                        <row>
                            <entry>currentItemCount</entry>
                            <entry>integer</entry>
                            <entry>Number of items on this page</entry>
                        </row>
                        <row>
                            <entry>itemCountPerPage</entry>
                            <entry>integer</entry>
                            <entry>Maximum number of items available to each page</entry>
                        </row>
                        <row>
                            <entry>last</entry>
                            <entry>integer</entry>
                            <entry>Last page number</entry>
                        </row>
                        <row>
                            <entry>lastItemNumber</entry>
                            <entry>integer</entry>
                            <entry>
                                Absolute number of the last item on this page
                            </entry>
                        </row>
                        <row>
                            <entry>lastPageInRange</entry>
                            <entry>integer</entry>
                            <entry>
                                Last page in the range returned by the
                                scrolling style
                            </entry>
                        </row>
                        <row>
                            <entry>next</entry>
                            <entry>integer</entry>
                            <entry>Next page number</entry>
                        </row>
                        <row>
                            <entry>pageCount</entry>
                            <entry>integer</entry>
                            <entry>Number of pages</entry>
                        </row>
                        <row>
                            <entry>pagesInRange</entry>
                            <entry>array</entry>
                            <entry>
                                Array of pages returned by the scrolling style
                            </entry>
                        </row>
                        <row>
                            <entry>previous</entry>
                            <entry>integer</entry>
                            <entry>Previous page number</entry>
                        </row>
                        <row>
                            <entry>totalItemCount</entry>
                            <entry>integer</entry>
                            <entry>Total number of items</entry>
                        </row>
                    </tbody>
                </tgroup>
            </table>
        </sect3>
    </sect2>
</sect1>
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