How to use Django template variable on attr or set_data

[andreccorrea]

Is there any way to use a template variable as param for attr or set_data tags?

Something like:

{% render_field field|set_data:"my-data:{{ template_variable }}" %}

Doing the above passes literally the string '{{ template_variable }}' to my-data attribute and not the variable value as expected.

[bblanchon]

It seems the only option is to use render_field, see #68.

[danielniccoli]

@bblanchon I have the same need. I am not sure if I understand your reply, because OP is already using {% render_field ... %}.

I would need a way to add a string that contains a string and the value from a variable, much like OP. Specifically, to render the aria-labelledby attribute

Both these solutions don't work:

{{ field|attr:"aria-labelledby:{{ field.label}}Help" }}
{% render_field field|aria-labelledby:"{{ field.label}}Help" %}

# Needed to link the label to the help text
{% if field.help_text %}
    <div id="{{ field.label }}Help" class="form-text">
        {{ field.help_text | safe }}
    </div>
{% endif %}

[bblanchon]

I think what I meant to say is that @andreccorrea's only option was to do this:

{% render_field field my-data=template_variable %}

However, in your case @danielniccoli, you must append "help" to the string before passing it to {% render_field %}.
As far as I know, you cannot do this in one shot, so you need to create an additional context variable using {% with %}, like so:

{% with help_id=form.name.id_for_label|add:'_help' %}
{% render_field field aria-labelledby=help_id %}
<div id="{{ help_id }}" class="form-text">{{ field.help_text }}</div>
{% endwith %}

[danielniccoli]

{% with help_id=form.name.id_for_label|add:'_help' %}
                                       ^^^                                              

That solved my problem! I wasn't aware I could use |add that way. Thank you!