Register your own smarty helper plugin in PrestaShop

In this blog, we are going to learn how to register your own smarty helper plugin in PrestaShop. PrestaShop uses a Smarty template engine for the view section. Smarty is open source and provides flexibility for custom development.

PrestaShop has already registered its own helper plugin like displayPrice, convertPrice, displayWtPrice, etc.

We can directly use it in our smarty file.

For example:

{displayPrice price=$price currency=$id_currency}

We will learn how to create and register our own smarty helper plugin.

Smarty provides a method registerPlugin() which provides the facility to register plugins dynamically. But this method is not directly available in our module, PrestaShop has an alternative function smartyRegisterFunction that is available globally.

This function takes 6 parameters:

Parameter	Required	Description
$smarty	Yes	Pass smarty object (ie: $this->context->smarty)
$type	Yes	Plugin type: function, modifier, or block
$function	Yes	Your function name
$params	Yes	Array of parameters
$lazy	No	Pass as true if the function is not called on every page
$initial_lazy_register	No	Allows to only load external classes when they are needed

Types of plugins in PrestaShop:

There are 3 plugins in the PrestaShop:

• Function
• Modifier
• Block

Function plugin:

All attributes passed to template functions from the template are contained in the $params as an associative array.

ie:

smartyRegisterFunction(
    $this->context->smarty,
    'function',
    'displayProductQuantity',
    [
        'WkTestClass',
        'displayProductQuantity'
    ]
);

Create a WkTestClass and create a static method displayProductQuantity:

ie:

class WkTestClass
{
    public static function displayProductQuantity($params)
    {
        if (!$params['id_product']) {
            return false;
        }

        return StockAvailable::getQuantityAvailableByProduct((int)$params['id_product']);
    }
}

Now, you can use this function in smarty like below:

{displayProductQuantity id_product='1'}  // Print available stock for product ID: 1

Modifier plugin:

Modifiers are little functions that are applied to a variable in the template before it is displayed or used in some other context. Modifiers can be chained together.

smartyRegisterFunction(
    $this->context->smarty,
    'modifier',
    'removeSlashes',
    [
        'WkTestClass',
        'removeSlashesFromString'
    ]
);

Create a WkTestClass and create a static method removeSlashesFromString:

class WkTestClass
{
    public static function removeSlashesFromString($params)
    {
        if (!$params) {
            return false;
        }

        return stripslashes($params);
    }
}

You can use this modifier in smarty like:

{"Who\'s Peter Griffin?"|removeSlashes}  // Output: Who's Peter Griffin?

Modifier plugin:

Block functions are functions of the form: {func} .. {/func}. In other words, they enclose a template block and operate on the contents of this block.

ie:

smartyRegisterFunction(
    $this->context->smarty,
    'block',
    'getFormattedProductInfo',
    [
        'WkTestClass',
        'getFormattedProductInfo'
    ]
);

Create a WkTestClass and create a static method getFormattedProductInfo:

public static function getFormattedProductInfo($params, $content, $smarty = null, &$repeat = false)
{
    // only output on the closing tag
    if (!$repeat && isset($params) && Tools::strlen($content)) {
        $objProduct = new Product((int)$params['id_product'], false, (int)$params['id_lang']);
        echo sprintf(
            $content,
            $objProduct->name,
            StockAvailable::getQuantityAvailableByProduct((int)$params['id_product'])
        );
    }
}

You can use this block in smarty like:

{getFormattedProductInfo id_product='1' id_lang='1'}
This product name is %s which current stock is %d.
{/getFormattedProductInfo}

// Output: This product name is Hummingbird printed t-shirt which current stock is 2397.

Note: In the block plugin, by default, the function getFormattedProductInfo is called twice by Smarty: once for the opening tag, and once for the closing tag. At the first call, the $repeat param value is true but the $content param is null that’s why I have checked for $repeat param value to false because at the second call, this value is false and the actual $content value exists.

That’s all about this blog.

If any issue or doubt please feel free to mention it in the comment section.

I would be happy to help.

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