I would like to detect if a header in the current request is present and obtain its value, directly within a Twig template.
I know that craft.app.request gives access to a few variables like isAjax that directly check the headers content, but I haven't found a method to directly retrieve a specific header.
Can this be achieved in some way? (preferably not by writing a plugin)
By checking the code, I could find a method named getHeaders() that will return all the headers of the current request.
So if you want to retrieve the content of the foo header, just use:
{% set headers = craft.app.request.getHeaders() %}
{% set fooHeader = headers['foo'] %}
headers variable as an array will result in a Twig Runtime Error, specifically Key "foo" in object with ArrayAccess of class "yii\web\HeaderCollection" does not exist.. Using the get method for the HeaderCollection is recommend, as follows, {{ headers.get('foo') }}
craft.app.request.getHeaders() returns an instance of yii\web\HeaderCollection, which has a number of public methods you can use from a Twig template.
For example, to see if an isAjax header is present:
{# Get the header collection #}
{% set headers = craft.app.request.getHeaders() %}
{# Test for specific header #}
{% set isAjaxRequest = headers.has('isAjax') %}
{% if isAjaxRequest %}
{# Do something... #}
{% endif %}
If you need to read the value of a header, use the get() method.
