pass block into embed and forward to another embed?

Question

I'm trying to achieve some modularity using embeds, but with the possiblity to extend/inject customizations from the including template.

Consider the following scenario:

Have a modular partial which contains a form, say form.twig I want the ability to add new form fields at the end of the form, but using the otherwise common form.twig, so I add a {% block form_extension %} in form.twig

I have another page template, that includes/embed that partial, say page.twig. Now, this works, I just add a block when embedding, and it gets injected.

But, I also have another modular partial, say partial_with_form.twig, that embeds form.twig. And I want to be able to define the form_extension block, when embedding partial_with_form.

Is this even possible? I have tried with parent() and block(), but none of them can give me the content of the supplied block unless I specify the targeting block in partial_with_form. But then it will be outputted there...

Answer 1

If partial_with_form.twig isn’t making any of its own customizations to form.twig, then I’d just include the form.twig template using an {% include %} tag, and wrap that whole thing with a {% block %}, so if a template wants to include the partial and make changes to the form, they can just redefine the form themselves.

partial_with_form.twig:

{% block form %}
  {% include 'form' %}
{% endblock %}

Other template:

{% embed `partial_with_form` %}
  {% block form %}
    {% embed 'form' %}
      {% block form_extension %}
        <!-- ... -->
      {% endblock %}
    {% endembed %}
  {% endblock %}
{% endembed %}

Answer 2

Hm, seems like you can use block() but it can't be within the embed block. Putting it in a variable first and use that variable in the embed block works.

{% set petition_after_fields_block = block('petition_after_fields') is defined ? block('petition_after_fields') %}
{% embed 'form' %}
    {% block petition_after_fields %}
        {{ petition_after_fields_block|raw }}
        {# {{ block('petition_after_fields') }} -- This doesn't work, nor using a different block name #}
    {% endblock %}
{% endembed %}