escape

The escape filter escapes a string using strategies that depend on the context. By default, it uses the HTML escaping strategy:

<p>
  {{ user.username | escape }}
</p>

For convenience, the e filter is defined as an alias:

<p>
  {{ user.username | e }}
</p>

The escape filter can also be used in other contexts than HTML thanks to an optional argument which defines the escaping strategy to use:

{{ user.username | e }}
{# is equivalent to #}
{{ user.username | e('html') }}

And here is how to escape variables included in JavaScript code:

{{ user.username | escape('js') }}
{{ user.username | e('js') }}

The escape filter supports the following escaping strategies for HTML documents:

  • html: escapes a string for the HTML body context.
  • js: escapes a string for the JavaScript context.
  • css: escapes a string for the CSS context. CSS escaping can be applied to any string being inserted into CSS and escapes everything except alphanumerics.
  • url: escapes a string for the URI or parameter contexts. This should not be used to escape an entire URI; only a subcomponent being inserted.
  • html_attr: escapes a string for the HTML attribute context.

Note that doing contextual escaping in HTML documents is hard and choosing the right escaping strategy depends on a lot of factors. Please, read related documentation like the OWASP prevention cheat sheet to learn more about this topic.

When using automatic escaping, Canvas tries to not double-escape a variable when the automatic escaping strategy is the same as the one applied by the escape filter; but that does not work when using a variable as the escaping strategy:

{% set strategy = 'html' %}

{% autoescape 'html' %}
  {{ var | escape('html') }} {# won't be double-escaped #}
  {{ var | escape(strategy) }} {# will be double-escaped #}
{% endautoescape %}

When using a variable as the escaping strategy, you should disable automatic escaping:

{% set strategy = 'html' %}

{% autoescape 'html' %}
  {{ var | escape(strategy) | raw }} {# won't be double-escaped #}
{% endautoescape %}

Arguments

Argument Description Type
strategy The escaping strategy String
charset The string charset String