Question

I need to render data with unknown type with filters that specific on each data type:

the rendered structures looks like:

array(
    "value"  => "value-to-render",
    "filter" => "filter-to-apply",
)

{% for item in items %}
    {{ item.value|item.filter|raw}}
{% endfor %}

So My Question is: How can I get twig to use item.filter as a filter on the value?

Answer 1

You have to write your filter, which will call filters by passing name to it.

How to initially write you Extension you can read here.

Assuming that you have created you extension, you have define your custom function, (e.g., customFilter).

//YourTwigFilterExtension.php

public function getFunctions()
{
    return array(
        ...
        'custom_filter' => new \Twig_Function_Method($this, 'customFilter'),
    );
}

Then, you have to define this function

public function customFilter($context, $filterName)
{
    // handle parameters here, by calling the 
    // appropriate filter and pass $context there
}

After this manipulations you’ll be able to call in Twig:

{% for item in items %}
    {{ custom_filter(item.value, item.filter)|raw  }}
{% endfor %}

Or, if you’ve defined your filter as filter (not as function):

{% for item in items %}
    {{ item.value|custom_filter(item.filter)|raw  }}
{% endfor %}