How to combine change_list_template in ModelAdmin mixin

[ecas]

I would like to create a mixin to extend the ModelAdmin class that adds a description text to the view, overriding the default change_list_template.

[admin_extra.py]

class DescriptionAdminMixin(object)

change_list_template = "description_change_list.html"

...

    def changelist_view(self, request, extra_context=None):

        extra_context = extra_context or {}

        extra_context.update({

            'description': self.description,

        })

        return super(DescriptionAdminMixin, self).changelist_view(request, extra_context=extra_context)

[description_change_list.html]

{% extends "admin/change_list.html" %}

{% block object-tools %}

{% block description %}

{% if description %}{{ description }}{% endif %}

{% endblock description %}

{{ block.super }}

{% endblock %}

This works fine if used on a ModelAdmin, but it fails if used on an already subclassed ModelAdmin that also defines change_list_template, as it gets overwritten.

Ex. adding django-import-export mixin:

class MyModelAdmin(DescriptionAdminMixin, ExportMixin, ModelAdmin): 

...

where ExportMixin is defined as:

class ExportMixin(ImportExportMixinBase):

...

    change_list_template = 'admin/import_export/change_list_export.html'

    ...

Is there a preferred way to combine both templates?

The solution I use for now is defining a parent_template in the context, and use that in the template to extend from it

[admin_extra.py]

class DescriptionAdminMixin(object)

    change_list_template = "description_change_list.

    ...

    def changelist_view(self, request, extra_context=None):

        # Define parent object template, or use the default admin change list template

        opts = self.model._meta

        app_label = opts.app_label

        parent_template_list = super(DescriptionAdminMixin, self).change_list_template or [

            'admin/%s/%s/change_list.html' % (app_label, opts.model_name),

            'admin/%s/change_list.html' % app_label,

            'admin/change_list.html'

            ]

        parent_template = SimpleTemplateResponse(None).resolve_template(parent_template_list)

        extra_context = extra_context or {}

        extra_context.update({

            'description': self.description,

            'parent_template': parent_template,

        })

        return super(DescriptionAdminMixin, self).changelist_view(request, extra_context=extra_context)

[description_change_list.html]

{% extends parent_template %}

{% block object-tools %}

{% block description %}

{% if description %}{{ description }}{% endif %}

{% endblock description %}

{{ block.super }}

{% endblock %}

Is there any better solution? Is there a way for the AdminObject to provide the default template, something like get_change_list_template() to avoid doing the template resolution? Or even better some built-in way of getting the template of the parent class?