Accessing the database from a view using Volt

The purpose of the MVC pattern is to separate models, views and controllers into easily manageable blocks. Accessing the database directly from a view seriously violates that idea.

That being said, you may use the database connection service:

// some/view.volt
{{ set rows = db.fetchAll("SELECT * FROM tbl") }}

{{ db.execute("INSERT INTO tbl (col) VALUES ('val')") }}

{{ set statement = db.prepare("UPDATE tbl SET col=?") }}
{{ statement.execute(['val']) }}

Using Models in the view is more tricky, you could either embed a PHP block

// some/view.volt
<?php
$mdl = SomeModel::findFirst();
?>

{{ mdl.getName() }}

or create a helper service:

// ModelHelper.php
class ModelHelper
{
    public function create($modelName, array $assign=[])
    {
        return new $modelName($assign);
    }
    public function findFirst($modelName, $parameters=null) {
        $a = func_get_args();
        $modelName = array_shift($a);
        return forward_static_call_array([$modelName,'findFirst'], $a);
    }
}

// services.php
$di->set('modelHelper', function() {
    return new ModelHelper;
});

// some/view.volt
{{ modelHelper.findFirst('SomeModel', ['conditions'=>'id=2'])->getName() }}