Display custom message for checkbox (terms of service/privacy) - php

Question

I am still new to Symfony and Php, so I am using the CheckboxType code from Symfony docs.
Currently no message is appearing if a user attempts to register and the checkbox is unchecked, but it will still prevent the user from making a account.
(1) I would like a error message to appear next to the checkbox in red stating the box must be checked in order to proceed. I would also like to customize this message.
Thank you!
Register.html
{% extends 'base.html.twig' %}
{% block body %}
<div class="container">
<div class="row">
<div class="col-xs-12">
<h1>Register!</h1>
{{ form_start(form) }}
{{ form_row(form.username) }}
{{ form_row(form.email) }}
{{ form_row(form.plainPassword.first, {
'label': 'Password'
}) }}
{{ form_row(form.plainPassword.second, {
'label': 'Repeat Password'
}) }}
Terms of service
{{ form_widget(form.termsAccepted) }}
cancel
<button type="submit" class="btn btn-primary" formnovalidate>
Register
</button>
<br></br>
<p>Privacy Policy
{{ form_end(form) }}
</div>
</div>
</div>
{% endblock %}
RegistrationForm.php
class UserRegistrationForm extends AbstractType
{
public function buildForm(FormBuilderInterface $builder, array $options)
{
$builder
->add('email', EmailType::class)
->add('username', TextType::class)
->add('plainPassword', RepeatedType::class, ['type' => PasswordType::class])
->add('termsAccepted', CheckboxType::class, array(
'mapped' => false,
'constraints' => new IsTrue(),));
}
public function configureOptions(OptionsResolver $resolver)
{
$resolver->setDefaults([
'data_class' => User::class,
'validation_groups' => ['Default', 'Registration']
]);
}
}

Answer 1

The problem is that you are using:
{{ form_widget(form.termsAccepted) }}
for rendering the checkbox. This will only render the widget, whereas:
{{ form_row(form.termsAccepted) }}
as is used by all the user fields would contain the label, the widget and the error message. If you want to keep the widget, e.g. because using form_row messes up the template somehow you could render the errors individually using:
{{ form_errors(form.termsAccepted) }}
You might also want to check out the documentation on Form Customization.