NON_FIELD_ERRORS should be accessible via Form.errors.as_data() in a template

[sebastian.annies@…]

A naive developer would try to access the non-field errors in a template like that:

{% for messages in form.errors.as_data.__all__ %}
    {% for message in messages %}
            <div class="alert alert-error">{{ message }}</div>
    {% endfor %}
{% endfor %}

Unfortunately this is not possible as

Variables and attributes may not begin with underscores: 'form.errors.as_data.__all__'

The key should not start with underscore to make the data accessible in templates

[Matthias Erll]

The behavior is intentional, and it should not be necessary to access this field in a template directly. In order to render non-field-errors in templates, use non_field_errors() instead; alternatively iterating over all errors in the errors attribute is still possible. The new methods as_data() and as_json() are more useful for other output formats such as JSON responses.