Django: Displaying formset errors correctly

Question

I have an inline formset for a model, which has a unique_together constraint. And so, when I input data, which doesn't fulfill this constraint, it displays:

__all__Please correct the duplicate values below.

The code, which does this is:

    {% for error in formset.errors %}
        {{ error }}<br/>
    {% endfor %}

I don't much like the __all__ at the beginning of the error and it is quite clearly the dictionary key, so I tried:

    {% for key, error in formset.errors %}
        {{ key }}: {{ error }}<br/>
    {% endfor %}

But then all I get is:

__all__:

{{ error }} won't display at all. So what's going on here? And how do I display the error correctly?

Answer 1

I think the problem here is that formset.errors is a list of dictionaries, not a single dictionary.

From the Django docs page on formsets:

>>> formset.errors
[{}, {'pub_date': [u'This field is required.']}]

See if something like this fixes the problem: (Updated based on the askers comments)

{% for dict in formset.errors %}
    {% for error in dict.values %}
        {{ error }}
    {% endfor %}
{% endfor %}

If that fails, I'd try using manage.py shell, and try to reproduce your situation in the python shell... that way it will be easy to inspect the various values and figure out what you need to do.

Answer 2

The for loops are unnecessary, these errors should be correctly displayed with the following:

{{ formset.non_form_errors }}

Answer 3

Here is a clarification for anyone encountering similar issues of errors not being rendered in template:

If you have and error regarding the formset as a whole, use:

{{ formset.non_form_errors }}

this basically returns errors in __all__ entry from formset.errors. It is documented as:

    """
    Returns an ErrorList of errors that aren't associated with a particular
    form -- i.e., from formset.clean(). Returns an empty ErrorList if there
    are none.
    """

However if you are rendering forms from formset and some errors are not being renderd, you are probably missing:

{% for form in formset.forms %}
    {# ... #}
    {{ form.non_field_errors }}
{% endfor %}

this returns errors in __all__ entry from form.errors. Those are, analogous to the non_form_errors, the errors that aren't associated with a particular field, but rather with the field relations. For example if you had a form with fields From and To, and you validate if From value is smaller then To value, the tag {{ form.non_field_errors }} could render the following error:

'The From value must be smaller than the To value'

Answer 4

Django 1.6 formsets have a new method, BaseFormSet.total_error_count. Using this in a template conditional ensures you only will output errors and markup if at least one error exists in the formset.

{% if formset.total_error_count %}
    <ul class="errorList">
    {% for dict in formset.errors %}
        {% for error in dict.values %}
        <li>{{ error }}</li>
        {% endfor %}
    {% endfor %}
    </ul>
{% endif %}

See the Django docs page for v1.6+.