Twig variables in twig variable - twig

Question

I have a twig variable html. To show it in a twig template I do {{html}}.
That variable looks like:
<div>{{region_top}}</div><div>{{region_center}}</div>
region_* is a variable too. When Twig parses my html variable, it doesn't parse the inner variables (regions).
What I should do?

Answer 1

I have twig variable html. To show it in twig template I do {{html}}. That variable look like {{region_top}}{{region_center}}. region_* is variables too. When twig parse my html variable he didn't parse inner variables (regions). What can I should do?
Twig takes your strings as a literal string, meaning you'll see the content of the variable, escaped. If you want it to be able to display {{region_top}} as well, I'd recommend something like this:
{{html|replace({'{{region_top}}': region_top, '{{region_center}}': region_center})}}
If the content of your html variable is also dynamic (meaning it can contain more than just those two variables), I'd write a twig plugin which can do what you want. Writing plugins is pretty easy to do.
EDIT: Here's the extension I just finished writing.
EDIT 2: The extension now uses the environment to render the string, so it evaluates the string, instead of just replacing variables. This means your variable can contain anything a template can, and it will be render and escaped by Twig itself. I'm awesome.
<?php
/**
* A twig extension that will add an "evaluate" filter, for dynamic evaluation.
*/
class EvaluateExtension extends \Twig_Extension {
/**
* Attaches the innervars filter to the Twig Environment.
*
* #return array
*/
public function getFilters( ) {
return array(
'evaluate' => new \Twig_Filter_Method( $this, 'evaluate', array(
'needs_environment' => true,
'needs_context' => true,
'is_safe' => array(
'evaluate' => true
)
))
);
}
/**
* This function will evaluate $string through the $environment, and return its results.
*
* #param array $context
* #param string $string
*/
public function evaluate( \Twig_Environment $environment, $context, $string ) {
$loader = $environment->getLoader( );
$parsed = $this->parseString( $environment, $context, $string );
$environment->setLoader( $loader );
return $parsed;
}
/**
* Sets the parser for the environment to Twig_Loader_String, and parsed the string $string.
*
* #param \Twig_Environment $environment
* #param array $context
* #param string $string
* #return string
*/
protected function parseString( \Twig_Environment $environment, $context, $string ) {
$environment->setLoader( new \Twig_Loader_String( ) );
return $environment->render( $string, $context );
}
/**
* Returns the name of this extension.
*
* #return string
*/
public function getName( ) {
return 'evaluate';
}
}
Example usage:
$twig_environment->addExtension( new EvaluateExtension( ) );
In the template:
{% set var = 'inner variable' %}
{{'this is a string with an {{var}}'|evaluate}}

Answer 2

See http://twig.sensiolabs.org/doc/functions/template_from_string.html
It seems that this is frequently missed as most folks think (and search for) "eval" when expecting a filter/function to evaluate in the current language they're drafting in. Template from string isn't the first search query that comes to mind.

Answer 3

One option is to render your templates as strings. You can do that like this:
$env = new \Twig_Environment(new \Twig_Loader_String());
echo $env->render(
"Hello {{ name }}",
array("name" => "World")
);
I'll leave it to you to decide how exactly to structure your code to make this work, but it might go something like this:
1) Fetch the inner template text that contains the variables that aren't being replaced.
2) Render that inner template text into an $html variable. Be sure to pass in any vars you need.
3) Render your original template that contains {{html}}. Be sure to pass in 'html' => $html in the vars array

Answer 4

You can also pass an array or an object to the view, and then use the twig attribute() method: http://twig.sensiolabs.org/doc/functions/attribute.html
{% if attribute(array, key) is defined %}
{{ attribute(array, key) }}
{% endif %}