form_errors(form) symfony2 twig - forms

Question

Using Symfony2.3.4 and Twig
I bet it's an easy peasy for anybody but I just can't get it done.
I'm trying to show only one error alert with always the same message, always at the beginnig of the form, everytime there are errors regardless which field contains the invalid input.
I thought I could do it like this:
//../Professor/Resources/new.html.twig
{% extends 'AdminBundle:Default:admin.html.twig' %}
{% block content -%}
<h1>New professor</h1>
{% if form_errors(form) is not null %} {#<------------------------------------#}
<div class="alert alert-error">
<i class="glyphicon-ban-circle"></i> Message.
</div>
{% endif %}
<div class="row-fluid">
<form id="prof_create" class="form-horizontal sf_admin_form_area" action="{{ path('professor_create') }}"
method="post" {{ form_enctype(form) }}>
{{ form_widget(form) }}
<div class="row-fluid">
<div class="span8"></div>
</div>
<div class="form-actions">
<button class="btn btn-primary">
<i class="icon-ok"></i> {{'Create' | trans}}</button>
<a class="btn" href="{{ path('professor') }}">
<i class="icon-ban-circle"></i> {{'Cancel' | trans }}</a>
</div>
</form>
</div>
{% endblock %}
{% if form_errors(form) is not null %} is not working, meaning:
when I show the create form for the first time before entering any data in the fields,the error alert shows although there is no data in the fields.
I also tried {% if form_errors(form) %} which is also useless but the other way around, it doesn't matter if there are or not errors, the alert just won't show.
There's obviously a lot about form_errors(form) that I don't know.
Appreciate any tips or even completely different solutions.
Thanks

Answer 1

Have you try this ?
{% if form_errors(form.content) is not empty %}

Answer 2

try:
{% if form_errors(form) != '' %}
...
{% endif %}
You will also need to make sure that the error_bubbling option on all of your fields is set to true. If you dont the error only exists on the child. So the main form wouldnt have any errors even though some of the children do.
To set the error bubbling you need to do it to each field:
//Some FormType that you have created
class CustomFormType extends AbstractType
{
public function buildForm(FormBuilderInterface $builder, array $options)
{
$builder->add('test', 'text', array('error_bubbling'=>true);
}
}
Your other option is to override the form_errors block like suggested in the accepted answer here:
{% block form_errors %}
{% spaceless %}
{% set a = false %}
{% for child in form.children %}
{% if child.get("errors") %}
{% set a = 'true' %}
{% endif %}
{% endfor %}
{% if a == true %}
<div class="alert">
{% for children in form.children %}
{{ form_errors(children) }}
{% endfor %}
</div>
{% endif %}
{% if errors|length > 0 %}
<ul>
{% for error in errors %}
{{
error.messagePluralization is null
? error.messageTemplate|trans(error.messageParameters, 'validators')
: error.messageTemplate|transchoice(error.messagePluralization, error.messageParameters, 'validators')
}}
{% endfor %}
</ul>
{% endif %}
{% endspaceless %}
{% endblock form_errors %}

Answer 3

try
{% if form.vars.errors|length %}

Answer 4

{% if not form.vars.valid %}
<div class="alert alert-error">
{{ form_errors(form) }}
</div>
{% endif %}
from https://stackoverflow.com/a/17826389/511514