如何在 Symfony2 Twig 模板中调用静态函数

Question

How to call my static function in twig template without passing through controller?

For example:

...
{{ MyStaticClass::getData() }}
...

My Static Class:

class MyStaticClass {
    const v1 = 'Value1';
    const v2 = 'Value2';
    ...

    public static function getData() {
        ...

        return $data;
    }
}

Answer 1

Instead of writing a Twig extension an easier / less bloated solution can sometimes be to simply pass a new instance of the class with the static methods to twig.

eg

// ...
$viewVars['MyStaticClass'] = new MyStaticClass();
// ...
$html = $twig->render('myTemplate.html.twig', $viewVars);

and in twig:

{{ MyStaticClass.getData() }}

Answer 2

You cannot directly call PHP in a twig template. You'll need to create a filter or function to do what you're looking.

$twig         = new Twig_Environment($loader, $params);
$twigFunction = new Twig_SimpleFunction('MyStaticClass', function($method) {
    MyStaticClass::$method
});
$twig->addFunction($twigFunction);

Then in your twig template just do:

{{ MyStaticClass('getData') }}

Of course the above example assumes MyStaticClass is within the scope of wherever you're twig.

Symfony Example

You must create a twig extentions. Example below:

namespace PurpleNeve\Web\PNWebBundle\Extensions;

use PurpleNeve\Web\PNWebBundle\DependencyInjection\CurrencyConverter;

class TwigCurrency extends \Twig_Extension
{
    private $converter;

    public function __construct(CurrencyConverter $converter)
    {
      $this->converter = $converter;
    }

    public function getName()
    {
        return 'currency';
    }

    public function getFilters()
    {
        return array(
            'convertCurrency' => new \Twig_Filter_Method($this, 'getConversionBetween')
        );
    }

    public function getConversionBetween($amount, $isoFrom, $isoTo="USD")
    {
        try {
          $value = $this->converter->convertAmount($amount, $isoFrom, $isoTo);
          return round($value,2);
        } catch(\Exception $e) {
          return "?";
        }
    }
}

This is an example of an extension I created to convert currency from one currency to another in twig.

To implement it, you need to create a service object for it in your services.yml

parameters:
    currency_converter.class: PurpleNeve\Web\PNWebBundle\DependencyInjection\CurrencyConverter

services:
    currency_converter:
        class: "%currency_converter.class%"
        arguments : [@doctrine.orm.entity_manager]

    twig.extension.currency:
        class: PurpleNeve\Web\PNWebBundle\Extensions\TwigCurrency
        tags:
            - { name: 'twig.extension' }
        arguments : [ @currency_converter ]

Then as above, within twig I can call that class and function using {{ convertCurrency(55505, 'CAD', 'USD) }}

Answer 3

A generic approach is to register a Twig helper function named callstatic to make the call.

$twig->addFunction(new \Twig_SimpleFunction('callstatic', function ($class, $method, ...$args) {
    if (!class_exists($class)) {
        throw new \Exception("Cannot call static method $method on Class $class: Invalid Class");
    }

    if (!method_exists($class, $method)) {
        throw new \Exception("Cannot call static method $method on Class $class: Invalid method");
    }

    return forward_static_call_array([$class, $method], $args);
}));

The main advantage of this approach is that it will work with any class and method combination.

Usage:

{# This will call \Mynamespace\Mypackage\Myclass::getStuff(); #}
{% set result = callstatic('\\Mynamespace\\Mypackage\\Myclass', 'getStuff') %}

It also supports arguments:

{# This will call \Mynamespace\Mypackage\Myclass::getStuff('arg1', 'arg2'); #}
{% set result = callstatic('\\Mynamespace\\Mypackage\\Myclass', 'getStuff', 'arg1', 'arg2') %}