Override label class in Bootstrap 3 horizontal layout in Symfony Twig Bridge

bootstrap_3_horizontal_layout.html.twig

{% use "bootstrap_3_layout.html.twig" %}

{% block form_start -%}
    {% set attr = attr|merge({class: (attr.class|default('') ~ ' form-horizontal')|trim}) %}
    {{- parent() -}}
{%- endblock form_start %}

{# Labels #}

{% block form_label -%}
{% spaceless %}
    {% if label is same as(false) %}
        <div class="{{ block('form_label_class') }}"></div>
    {% else %}
        {% set label_attr = label_attr|merge({class: (label_attr.class|default('') ~ ' ' ~ block('form_label_class'))|trim}) %}
        {{- parent() -}}
    {% endif %}
{% endspaceless %}
{%- endblock form_label %}

{% block form_label_class -%}
col-sm-2
{%- endblock form_label_class %}

{# Rows #}

{% block form_row -%}
    <div class="form-group{% if (not compound or force_error|default(false)) and not valid %} has-error{% endif %}">
        {{- form_label(form) -}}
        <div class="{{ block('form_group_class') }}">
            {{- form_widget(form) -}}
            {{- form_errors(form) -}}
        </div>
{##}</div>
{%- endblock form_row %}

{% block checkbox_row -%}
    {{- block('checkbox_radio_row') -}}
{%- endblock checkbox_row %}

{% block radio_row -%}
    {{- block('checkbox_radio_row') -}}
{%- endblock radio_row %}

{% block checkbox_radio_row -%}
{% spaceless %}
    <div class="form-group{% if not valid %} has-error{% endif %}">
        <div class="{{ block('form_label_class') }}"></div>
        <div class="{{ block('form_group_class') }}">
            {{ form_widget(form) }}
            {{ form_errors(form) }}
        </div>
    </div>
{% endspaceless %}
{%- endblock checkbox_radio_row %}

{% block submit_row -%}
{% spaceless %}
    <div class="form-group">
        <div class="{{ block('form_label_class') }}"></div>
        <div class="{{ block('form_group_class') }}">
            {{ form_widget(form) }}
        </div>
    </div>
{% endspaceless %}
{% endblock submit_row %}

{% block reset_row -%}
{% spaceless %}
    <div class="form-group">
        <div class="{{ block('form_label_class') }}"></div>
        <div class="{{ block('form_group_class') }}">
            {{ form_widget(form) }}
        </div>
    </div>
{% endspaceless %}
{% endblock reset_row %}

{% block form_group_class -%}
col-sm-10
{%- endblock form_group_class %}

fields.html.twig

{% block form_label_class -%}
col-sm-4
{%- endblock form_label_class %}

form.html.twig

{% extends 'SonataAdminBundle::standard_layout.html.twig' %}

{% block content %}

{% form_theme form 'bootstrap_3_horizontal_layout.html.twig' %}

{{ form_start(form, {'attr': {'novalidate': 'novalidate'} } ) }}

{{ form_widget(form.foo) }}

{{ form_row(form._token) }}

{{ form_end(form, {'render_rest': false}) }}

{% endblock %}

This way the label_class will not change. It still uses col-sm-2 instead of col-sm-2 defined here:
https://github.com/symfony/twig-bridge/blob/master/Resources/views/Form/bootstrap_3_horizontal_layout.html.twig#L21-L23

Any idea?

Original discussion:
https://twitter.com/webdevilopers/status/704774817963237376

Any idea @MatTheCat @lyrixx @javiereguiluz?

I solved this by creating my own form theme and extending the bootstrap_3_horizontal_layout theme:

{# app/Resources/views/Form/updated_bootstrap_3_horizontal_layout.html.twig #}

{% use "bootstrap_3_horizontal_layout.html.twig" %}

{% block form_label_class %}
col-sm-4
{% endblock %}

{% block form_group_class %}
col-sm-8
{% endblock %}

Then in the output file, use your new custom theme:

{% form_theme myForm 'Form/bootstrap_3_updated_horizontal_layout.html.twig' %}

Use this param horizontal_label_class to set class or false in form elements.