field_type filter is not a valid input for add_class filter

[jossperdomo]

Hi! I try add the field_type filter as a class to a field as a follow:

{% with "{{field|field_type}}" as field_type %} {% render_field field class+="form-control {{field_type}}" required="true" %} {% endwith %}

But this way doesn't work.

Please, anyone could tell me how add this filter as a field's class?

Thanks!

PD: I'm sorry for my English!