Override block within included template in Twig - symfony

Question

Currently using Symfony2 and Twig, I'm trying to override block within an included template. Let me explain :
{# base.html.twig #}
{% block content %}{% endblock content %}
<!--Some html Code -->
{% block javascripts %}
<!--Some scripts included like jQuery-->
{% endblock javascripts %}
In a other file:
{# page.html.twig #}
{% extends 'base.html.twig' %}
{% block content %}
{% include 'form.html.twig' %}
{% endblock content %}
And finally:
{# form.html.twig #}
<form method="post" action="something">
</form>
{# I am trying somehow to override the "javascripts" block here,
unfortunately I didn't figured out how to to that
#}
{% block javascripts %}
{{ parent() }}
<!--Some JS here-->
{% endblock javascripts %}
Is there a way to do what I want ?

Answer 1

What you need here is multiple inheritance. But just like php, twig does not have multiple inheritance. And just like php has traits, twig has a palliative for this called use. Remember that twig is compiled to php. I think a block that is used in a use statement ends up compiled in a trait.
First, create your a "trait" with the blocks you want to reuse in different places:
{% block my_form %}
<form method="post" action="something">
</form>
{% endblock %}
{% block form_specific_javascript %}
<!--Some JS here-->
{% endblock}
Then, in your page template, call the "trait", and reuse the blocks:
{# page.html.twig #}
{% extends 'base.html.twig' %}
{% block content %}
{% use 'form.html.twig' %}
{{ block('my_form') }}
{% endblock content %}
{# override the javascript block #}
{% block javascripts %}
{{parent()}}
{{block('form_specific_javascript')}}
{% endblock %}
So as you see, you can't do it all from the form template, you have to do some
wiring in your page template. Still, calling a block is better than copy / pasting
its contents, isn't it ?

Answer 2

Since i was looking for the same answer and actually found the solution.
It lies within TWIG with the embed tag.
Available in twig version 1.8, embed tag allows us to "include" a template, which has its own defined blocks who can then be overriden.
More information here: http://twig.sensiolabs.org/doc/tags/embed.html

Answer 3

You could just simply include form.html.twig within the javascripts block
base.html.twig
{% block content %}
<!--Some html Code -->
{% endblock content %}
{% block javascripts %}
<!--Some scripts included like jQuery-->
{% endblock javascripts %}
page.html.twig
{% extends 'base.html.twig' %}
{% block javascripts %}
{{ parent() }}
{% include 'form.html.twig' %}
{% endblock javascripts %}
form.html.twig
<!--Some JS here-->

Answer 4

I have exactly the same problem. I was looking for solution, but I didn't find any. Unfortunately include, embed and use does not solve this problem. But I figured two possible workarounds.
Option 1 (simpler, but needs more code)
Separate form into two files _form.html.twig and _form_js.html.twig and import them in the appropriate blocks.
Option 2
Invert hierarchy of templates. Extend form directly from base.
# form.html.twig
{% extends 'layouts/base.html.twig' %}
{% block body %}
{{ block('page_header') }}
{{ form_start(form) }}
{{ form_widget(form) }}
{{ form_end(form) }}
{% endblock %}
{% block javascripts %}
{{ parent() }}
<script>
# ...
</script>
{% endblock %}
And then extend form in other templates like new and edit.
# new.twig.html
{% extends 'form.html.twig' %}
{% block page_header %}
# custom content here
{% endblock %}

Answer 5

Using your own files, this is the approach I used and it worked for me:
{# base.html.twig #}
{% block content %}
{% endblock %}
<!--Some html Code -->
{% block javascripts %}
<script>console.log('1st print')</script>
{% endblock %}
In other file:
{# page.html.twig #}
{% extends 'base.html.twig' %}
{% block content %}
<h1>Welcome to page.html.twig.</h1>
<p>Here is a form for you to complete:</p>
{{ block("content", "form.html.twig") }}
{% endblock %}
{% block javascripts %}
{{ parent() }}
<script>console.log('2nd print')</script>
{{ block("formjavascripts", "form.html.twig") }}
{% endblock %}
And finally:
{# form.html.twig #}
{% block content %}
<form method="post" action="something">
</form>
{% endblock %}
{% block formjavascripts %}
<script>console.log('3rd print')</script>
{% endblock %}
Please notice the use of block function, you can find more info here https://twig.symfony.com/doc/3.x/functions/block.html
Also notice I used "formjavascripts" you could have used "javascripts" as well because that is the block name being retrieved from forms.html.twig file.
Note: You could try using Block function again in forms.html.twig and see if you can do a 4th print and call a 4th twig file! (Not sure if this last thing will work though :P)