Randomise & limit Category thumbs on homepage magento

问题

The following code simply displays the category thumbs for all subcategories in "category 12" im looking for a way to limit this number to 6 categories and have it be a random selection of those categories.

    <ul class="brand_list">
        <?php $media = Mage::getBaseUrl(Mage_Core_Model_Store::URL_TYPE_MEDIA); ?>
        <?php $children = Mage::getModel('catalog/category')->getCategories(12);   ?>
        <?php foreach ($children as $category): ?>
            <?php $category = Mage::getModel('catalog/category')->load($category->getId()); ?>
            <li class="span3">
                <a href="<?php echo $category->getUrl(); ?>">
                    <img alt="<?php echo $category->getName(); ?>" src="<?php echo $media; ?>/catalog/category/<?php echo $category->getThumbnail(); ?>" />
                </a>
            </li>
        <?php endforeach; ?>
    </ul>

i've used similar code before for products using the following two pieces of code:

<?php $collection->getSelect()->order('rand()'); ?>

<?php $_columnCount = $this->getColumnCount(); ?>
<?php $i=0; foreach ($collection->getItems() as $category): if($i==6){break;}?>
<?php if ($i++%$_columnCount==0): ?> 
<?php endif ?>

i have tried recoding this to suit the category thumbs but i don't seem to be having any joy.

回答1:

The solution to your question is bellow. I wouldn't use mysql rand() function since it's quite slow.

<ul class="brand_list">
  <?php 
    $media = Mage::getBaseUrl(Mage_Core_Model_Store::URL_TYPE_MEDIA);
    $parentCategory = Mage::getModel('catalog/category')->load(12);
    $children = Mage::getModel('catalog/category')
                  ->getCollection()
                  ->addIdFilter( array_rand( array_flip( $parentCategory->getAllChildren( true ) ), 6) )
                  ->addAttributeToSelect('name')
                  ->addAttributeToSelect('thumbnail');
  ?>
  <?php foreach ($children as $category): ?>
    <li class="span3">
      <a href="<?php echo $category->getUrl(); ?>">
        <img alt="<?php echo $category->getName(); ?>" src="<?php echo $media; ?>catalog/category/<?php echo $category->getThumbnail(); ?>" />
      </a>
    </li>
  <?php endforeach; ?>
</ul>

来源：https://stackoverflow.com/questions/14440874/randomise-limit-category-thumbs-on-homepage-magento