Custom list_editable field in django admin change list, which doesn't correspond directly to a model field

Question

Assuming my model looks like this (this is a simplified example):

class Person(Model):
  first_name = CharField(...)
  last_name = CharField(...)

  def name():
    return first_name + ' ' + last_name

Displaying the name as a single column in the admin change list is easy enough. However, I need a single, editable "name" field that is editable from the list page, which I can then parse to extract and set the model field values. The parsing isn't a concern. I am just wondering how to have an editable form field on the list page that doesn't correspond directly to a model field.

Answer 1

You should be able to do this in pure Python with a bit of work. Basically, you need to use the get_changelist_form method on the admin class to tell it to use a custom form rather than a default ModelForm for your instances, then initialize the custom field's value properly (most conveniently in the form's __init__ method) and specialize the save behavior of that form to set the first_name and last_name values.

Something like this should be a start:

class PersonChangeListForm(forms.ModelForm):
    class Meta:
        model = Person
    name = forms.CharField()

    def __init__(self, *args, **kwargs):
        instance = kwargs.get('instance')
        if instance:
            initial = kwargs.get('initial', {})
            initial['name'] = '%s %s' % (instance.first_name, instance.last_name)
            kwargs['initial'] = initial
        super(PersonChangeListForm, self).__init__(*args, **kwargs)

    def save(self, *args, **kwargs):
        # use whatever parsing you like here
        first_name, last_name = self.cleaned_data['name'].split(None, 1)
        self.cleaned_data['first_name'] = first_name
        self.cleaned_data['last_name'] = last_name
        return super(PersonChangeListForm, self).save(*args, **kwargs)

class PersonAdmin(admin.ModelAdmin):
    def get_changelist_form(self, request, **kwargs):
        return PersonChangeListForm

You will also need to declare a list_editable value that evaluates to True when tested as a boolean - some of the admin processing short-circuits without using the formset if list_editable does not evaluate as True .

If you have no other fields you want to be editable, this gets more complicated. The class validation requires that everything in the list_editable sequence be an editable field that's declared in list_display as well and is not a display link field. I think the options there are either to override the admin class's changelist_view method to use the full processing even if list_editable is not true, or to define a custom subclass of list or tuple that evaluates to True even when empty so it can pass validation. The former would require repeating a great deal of standard code and significantly increase your maintenance burden if you ever upgrade, while the latter is a counterintuitive hack and would not at all surprise me if it had unexpected consequences.

Neither are good options, so I hope you have at least one other field that makes sense to include in list_editable .

Answer 2

I just tried a quick mock-up of the problem in the admin. It seems that the admin validation fails for a field which is in list_editable that is not defined on the model. In short, the answer to your question seems to be no.

However, that doesn't mean it's not doable. With a bit of Javascript, you could use X-editable

(or roll your own), and make the "Name" column editable. Create a view to validate the data and save it to the model. Set X-editable field 'url' parameter to post to this URL. Obviously decorate your view with login_required / permissions_required etc, to make sure no-one else can edit the data.

Answer 3

Addition to @Peter DeGlopper answer: you may add other model field in list_editable (for example last_name ), then override change_list.html (look this answer How to override templates and add to the end of file some javascrip code: templates/admin/ your_app /person/change_list.html :

{% extends "admin/base_site.html" %}
{% load i18n admin_urls static admin_list %}
...

{% block content %}
...
{% endblock %}

{% block footer %}
{{ block.super }}
<script>
    var last_names = document.querySelectorAll('.field-last_name');

    last_names.forEach(function(el) {
        var input = el.children[0];
        var text = input.value;
        input.hidden = true;
        input.style.display = 'none';
        el.append(text);
    });
</script>
{% endblock %}