[Smarty 5.x] Assign custom resource‘s DB template metadata to Smarty directly?

[oliveratgithub]

I feel like this must be super simple, but I am lost even with the documentation and the (simple) examples.

I have a custom resource registered that loads Templates from the MySql DB. What I need is however not only to process the Smarty Template Source retrieved, but my Layout Wrapper must have all related Metadata stored along the template.

• How would one solve this best in a proper architectural way, with custom resource?
• Required on my .tpl wrapper are things like the Template's ID, its db stored Modified Date, its Creator, Parent Id, etc. Just everything stored along the template row

Simplifies Example:

<?php
use Smarty\Resource\CustomPlugin;

class DbTemplateResource extends CustomPlugin
{
    protected PDO $pdo;

    public function __construct(PDO $pdo)
    {
        $this->pdo = $pdo;
    }

    protected function fetch($name, &$source, &$mtime)
    {
        $sql = "
            SELECT
                template_source,
                id,
                created,
                parent_id
            FROM smarty_templates
            WHERE name = :name
            LIMIT 1
        ";

        $stmt = $this->pdo->prepare($sql);
        $stmt->execute([':name' => $name]);
        $row = $stmt->fetch(PDO::FETCH_ASSOC);

        if (!$row) {
            throw new SmartyException("Template '{$name}' not found in database");
        }

        // template source
        $source = $row['template_source'];

        // modification time for Smarty caching
        $mtime = strtotime($row['created']);

    }
}

// PDO connection
$pdo = new PDO(
    'mysql:host=localhost;dbname=app;charset=utf8mb4',
    'user',
    'password',
    [PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION]
);

// register resource
$smarty->registerResource('db', new DbTemplateResource($pdo));

// usage:
$smarty->display('db:home');

Usually of course i can do $smarty->assign() OUTSIDE of the custom resource. But for this I have to repeat the query & I'd like to not do that.

Thanks for any suggestions!

[wisskid]

You could do the query in a separate class and "remember" the result if you must. But I wouldn't worry about doing 2 queries. MySQL is extremely efficient, especially if you perform the exact same query twice.

[oliveratgithub]

Thanks @wisskid, I came to the same conclusion when going over the implementation again : as a custom Class Object is registered as the resource handler, the DB-query result can be passed as Dependency 👍 This also allows me to assign the Template information retrieved to both, my PHP app and Smarty Vars.

My concern was not really on performance, but more from an architectural standpoint; I find it confusing when same queries are executed in different parts.

The solution, abstracted for example purpose, looks something like this:

<?php
use Smarty\Resource\CustomPlugin;

class DbTemplateResource extends CustomPlugin
{
    protected string $tplsource;
    protected integer $tpltimestamp;

    public function __construct(string $templatesource, integer $timestamp)
    {
        $this->tplsource = $templatesource;
        $this->tpltimestamp = $timestamp;
    }

    protected function fetch($name, &$source, &$mtime)
    {
        // template source
        // (note that $smarty-assign() vars are available!)
        $source = $this->tplsource . '<small>Loaded via DbTemplateResource template name <i>{$template.id}</i></small>';

        // modification time for Smarty caching
        $mtime = this->tpltimestamp;
    }
}

// PDO connection
$pdo = new \PDO(
    'mysql:host=localhost;dbname=app;charset=utf8mb4',
    'user',
    'password',
    [PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION]
);

// Query Template data
$templatename = filter_input(INPUT_GET, 'page') ?: 'home';
$templatesource = "Template '{$name}' not found in database"; // Default = Error value
$templatetimestamp = 9999999999; // Default = Error value
$sql = "SELECT
                template_source,
                id,
                created,
                parent_id
            FROM smarty_templates
            WHERE name = :template
            LIMIT 1";
$stmt = $pdo->prepare($sql);
$stmt->execute([':template' => $templatename]);
$row = $stmt->fetch(PDO::FETCH_ASSOC);

// Assign queried template data
if ($row) {
    $templatesource = $row['template_source'];
    $templatetimestamp = strtotime($row['created']); // modification time for Smarty caching
}

// register resource with dependency injection
$smarty->registerResource('db', new \DbTemplateResource($templatesource, $templatetimestamp));

// usage with exposing additional values to use in Smarty Template
$smarty->assign('template', [ $row['id'], $row['parent_id'] ]);
$smarty->display('db:' . $templatename);