Today, Magento Tutorial will discuss with you how to convert multi-select field to checkbox in advanced search form of Magento.

Step 1:

Copy the following file to your working theme:
app/design/frontend/[interface]/[theme]/template/catalogsearch/advanced/form.phtml

 Step 2:

Open the form.phtml (from above) and find the following line just after the case ‘select’: ?>

<div class=“input-box”>

     <?php echo $this->getAttributeSelectElement($_attribute) ?>
    </div>

and replace it by the following code:

    <?php if(in_array($_attribute->getAttributeCode(), array(‘manufacturer’))): ?>
    <div class=“input-box”>
        <?php
             $options = $_attribute->getSource()->getAllOptions(false);
             foreach($options as $_option):
                 $isChecked = in_array($_option[‘value’],
$this->getRequest()->getParam($_attribute->getAttributeCode())) ? ‘ checked=”checked”‘ : null;
                 ?>
        <input type=”checkbox” name=”<?php echo $_attribute->getAttributeCode(); ?>[]“ value=”<?php echo $_option[‘value’]; ?>“<?php echo $isChecked; ?> /> <?php echo $_option[‘label’]; ?><br />
        <?php
             endforeach;
        ?>
    </div>
    <?php else: ?>
    <div class=“input-box”>
        <?php echo $this->getAttributeSelectElement($_attribute); ?>
    </div>
    <?php endif; ?>

Note: Here we have customized the display for manufacturer attribute, similarly you can customize for other attributes. Just you need to add the attribute code(for example: color) in the array as:

    <?php if(in_array($_attribute->getAttributeCode(), array(‘manufacturer’, ‘color’))): ?>

 Step 3:

Try to refresh the advanced search page: http://your-magento-url/catalogsearch/advanced

You will see:

Note: You can use some css in order to break the checkboxes in multi-columns for better display.