reverseadmin.py

"""
adminreverse from here http://djangosnippets.org/snippets/2032/
changed for working with ForeignKeys
Fixed for Django 1.6 by @andybak

reverseadmin
============
Module that makes django admin handle OneToOneFields in a better way.

A common use case for one-to-one relationships is to "embed" a model
inside another one. For example, a Person may have multiple foreign
keys pointing to an Address entity, one home address, one business
address and so on. Django admin displays those relations using select
boxes, letting the user choose which address entity to connect to a
person. A more natural way to handle the relationship is using
inlines. However, since the foreign key is placed on the owning
entity, django admins standard inline classes can't be used. Which is
why I created this module that implements "reverse inlines" for this
use case.

Example:

    from django.db import models
    class Address(models.Model):
        street = models.CharField(max_length = 255)
        zipcode = models.CharField(max_length = 10)
        city = models.CharField(max_length = 255)
    class Person(models.Model):
        name = models.CharField(max_length = 255)
        business_addr = models.ForeignKey(Address,
                                             related_name = 'business_addr')
        home_addr = models.OneToOneField(Address, related_name = 'home_addr')
        other_addr = models.OneToOneField(Address, related_name = 'other_addr')

This is how standard django admin renders it:

    http://img9.imageshack.us/i/beforetz.png/

Here is how it looks when using the reverseadmin module:

    http://img408.imageshack.us/i/afterw.png/

You use reverseadmin in the following way:

    from django.contrib import admin
    from django.db import models
    from models import Person
    from reverseadmin import ReverseModelAdmin
    class AddressForm(models.Form):
        pass
    class PersonAdmin(ReverseModelAdmin):
        inline_type = 'tabular'
        inline_reverse = ('business_addr', ('home_addr', AddressForm), ('other_addr' (
            'form': OtherForm
            'exclude': ()
        )))
    admin.site.register(Person, PersonAdmin)

inline_type can be either "tabular" or "stacked" for tabular and
stacked inlines respectively.

The module is designed to work with Django 1.6. Since it hooks into
the internals of the admin package, it may not work with later Django
versions.
"""

# TODO
# Never got this working but might come back to it
# class PurchaseOrderAdmin(ReverseModelAdmin):
#
#     inline_type = 'stacked'
#     inline_reverse = (
#         ('arrival', {
#             'fields': (
#                 ('start_location', 'time_at_start'),
#                 ('end_location', 'time_at_end'),
#                 ('transit_company', 'transit_person'),
#             ),
#         },),
#     )


from django.contrib.admin import helpers, ModelAdmin
from django.contrib.admin.options import InlineModelAdmin, csrf_protect_m, IS_POPUP_VAR
from django.contrib.admin.util import flatten_fieldsets, unquote
from django.core.urlresolvers import reverse
from django.db import transaction, models
from django.db.models import OneToOneField, ForeignKey
from django.forms import ModelForm
from django.forms.formsets import all_valid
from django.forms.models import BaseModelFormSet, modelformset_factory
from django.http import Http404
from django.utils.encoding import force_unicode, force_text
from django.utils.functional import curry
from django.utils.html import escape
from django.utils.safestring import mark_safe
from django.utils.translation import ugettext as _
from django.core.exceptions import PermissionDenied

class ReverseInlineFormSet(BaseModelFormSet):
    """
    A formset with either a single object or a single empty
    form. Since the formset is used to render a required OneToOne
    relation, the forms must not be empty.
    """
    model = None
    parent_fk_name = ''

    def __init__(
            self,
            data=None,
            files=None,
            instance=None,
            prefix=None,
            queryset=None,
            save_as_new=False):

        object = getattr(instance, self.parent_fk_name)

        if object:
            qs = self.model.objects.filter(pk = object.id)
            self.extra = 0
            self.max_num = 0
        else:
            qs = self.model.objects.filter(pk = -1)
            self.extra = 0
            self.max_num = 0

        super(ReverseInlineFormSet, self).__init__(
            data,
            files,
            prefix=prefix,
            queryset=qs
        )

        for form in self.forms:
            form.empty_permitted = False

def reverse_inlineformset_factory(
        model,
        parent_fk_name,
        form=ModelForm,
        fields=None,
        exclude=None,
        formfield_callback=lambda f: f.formfield()):

    kwargs = {
        'form': form,
        'formfield_callback': formfield_callback,
        'formset': ReverseInlineFormSet,
        'extra': 0,
        'can_delete': False,
        'can_order': False,
        'fields': fields,
        'exclude': exclude,
        'max_num': 0,
    }

    FormSet = modelformset_factory(model, **kwargs)
    FormSet.parent_fk_name = parent_fk_name
    return FormSet

class ReverseInlineModelAdmin(InlineModelAdmin):
    """
    Use the name and the help_text of the owning models field to
    render the verbose_name and verbose_name_plural texts.
    """
    def __init__(
            self,
            parent_model,
            parent_fk_name,
            model,
            admin_site,
            inline_type):

        self.template = 'admin/edit_inline/%s.html' % inline_type
        self.parent_fk_name = parent_fk_name
        self.model = model
        field_descriptor = getattr(parent_model, self.parent_fk_name)
        field = field_descriptor.field

        self.verbose_name_plural = field.verbose_name.title()
        self.verbose_name = field.help_text

        if not self.verbose_name:
            self.verbose_name = self.verbose_name_plural

        super(ReverseInlineModelAdmin, self).__init__(parent_model, admin_site)

    def has_add_permission(self, request):
        return False

    def get_formset(self, request, obj=None, **kwargs):

        if self.declared_fieldsets:
            fields = flatten_fieldsets(self.declared_fieldsets)
        else:
            fields = None
        if self.exclude is None:
            exclude = []
        else:
            exclude = list(self.exclude)

        # if exclude is an empty list we use None, since that's the actual
        # default
        exclude = (exclude + kwargs.get("exclude", [])) or None

        defaults = {
            "form": self.form,
            "fields": fields,
            "exclude": exclude,
            "formfield_callback": curry(self.formfield_for_dbfield, request=request),
        }

        defaults.update(kwargs)
        return reverse_inlineformset_factory(
            self.model,
            self.parent_fk_name,
            **defaults
        )

class ReverseModelAdmin(ModelAdmin):
    """
    Patched ModelAdmin class. The add_view method is overridden to
    allow the reverse inline formsets to be saved before the parent
    model.
    """
    def __init__(self, model, admin_site):

        super(ReverseModelAdmin, self).__init__(model, admin_site)

        # Initialize reverse_inline_instances

        if self.exclude is None:
            self.exclude = []

        self.reverse_inline_instances = []

        for field_config in self.inline_reverse:
            kwargs = {}
            if isinstance(field_config, tuple):
                field_name = field_config[0]
                if isinstance(field_config[1], dict):
                    kwargs = field_config[1]
                elif isinstance(field_config[1], ModelForm):
                    kwargs['form'] = field_config[1]
            else:
                field_name = field_config
            field = model._meta.get_field(field_name)

            if isinstance(field, (OneToOneField, ForeignKey)):
                name = field.name
                parent = field.related.parent_model
                inline = ReverseInlineModelAdmin(
                    model,
                    name,
                    parent,
                    admin_site,
                    self.inline_type
                )

                if kwargs:
                    inline.__dict__.update(kwargs)

                self.reverse_inline_instances.append(inline)
                self.exclude.append(name)

    def get_inline_instances(self, request, obj=None):
        inline_instances = super(ReverseModelAdmin, self).get_inline_instances(request, obj)
        return self.reverse_inline_instances + inline_instances

    @csrf_protect_m
    @transaction.atomic
    def add_view(self, request, form_url='', extra_context=None):
        "The 'add' admin view for this model."
        model = self.model
        opts = model._meta

        if not self.has_add_permission(request):
            raise PermissionDenied

        ModelForm = self.get_form(request)
        formsets = []
        inline_instances = self.get_inline_instances(request, None)
        if request.method == 'POST':
            form = ModelForm(request.POST, request.FILES)
            if form.is_valid():
                new_object = self.save_form(request, form, change=False)
                form_validated = True
            else:
                form_validated = False
                new_object = self.model()
            prefixes = {}
            for FormSet, inline in zip(self.get_formsets(request), inline_instances):
                prefix = FormSet.get_default_prefix()
                prefixes[prefix] = prefixes.get(prefix, 0) + 1
                if prefixes[prefix] != 1 or not prefix:
                    prefix = "%s-%s" % (prefix, prefixes[prefix])
                formset = FormSet(data=request.POST, files=request.FILES,
                                  instance=new_object,
                                  save_as_new="_saveasnew" in request.POST,
                                  prefix=prefix, queryset=inline.get_queryset(request))
                formsets.append(formset)

            if all_valid(formsets) and form_validated:

                # Here is the modified code.

                for formset, inline in zip(formsets, self.get_inline_instances(request)):
                    if not isinstance(inline, ReverseInlineModelAdmin):
                        continue
                    objects = formset.save()
                    if len(objects)==1:
                        setattr(new_object, inline.parent_fk_name, objects[0])

                # End modified code

                self.save_model(request, new_object, form, False)
                self.save_related(request, form, formsets, False)

                self.log_addition(request, new_object)
                return self.response_add(request, new_object)
        else:
            # Prepare the dict of initial data from the request.
            # We have to special-case M2Ms as a list of comma-separated PKs.
            initial = dict(request.GET.items())
            for k in initial:
                try:
                    f = opts.get_field(k)
                except models.FieldDoesNotExist:
                    continue
                if isinstance(f, models.ManyToManyField):
                    initial[k] = initial[k].split(",")
            form = ModelForm(initial=initial)
            prefixes = {}
            for FormSet, inline in zip(self.get_formsets(request), inline_instances):
                prefix = FormSet.get_default_prefix()
                prefixes[prefix] = prefixes.get(prefix, 0) + 1
                if prefixes[prefix] != 1 or not prefix:
                    prefix = "%s-%s" % (prefix, prefixes[prefix])
                formset = FormSet(instance=self.model(), prefix=prefix,
                                  queryset=inline.get_queryset(request))
                formsets.append(formset)

        adminForm = helpers.AdminForm(form, list(self.get_fieldsets(request)),
            self.get_prepopulated_fields(request),
            self.get_readonly_fields(request),
            model_admin=self)
        media = self.media + adminForm.media

        inline_admin_formsets = []
        for inline, formset in zip(inline_instances, formsets):
            fieldsets = list(inline.get_fieldsets(request))
            readonly = list(inline.get_readonly_fields(request))
            prepopulated = dict(inline.get_prepopulated_fields(request))
            inline_admin_formset = helpers.InlineAdminFormSet(inline, formset,
                fieldsets, prepopulated, readonly, model_admin=self)
            inline_admin_formsets.append(inline_admin_formset)
            media = media + inline_admin_formset.media

        context = {
            'title': _('Add %s') % force_text(opts.verbose_name),
            'adminform': adminForm,
            'is_popup': IS_POPUP_VAR in request.REQUEST,
            'media': media,
            'inline_admin_formsets': inline_admin_formsets,
            'errors': helpers.AdminErrorList(form, formsets),
            'app_label': opts.app_label,
            'preserved_filters': self.get_preserved_filters(request),
        }
        context.update(extra_context or {})
        return self.render_change_form(request, context, form_url=form_url, add=True)

    # TODO Not sure we need this
    #
    # @csrf_protect_m
    # @transaction.atomic
    # def change_view(self, request, object_id, form_url='', extra_context=None):
    #     "The 'change' admin view for this model."
    #     model = self.model
    #     opts = model._meta
    #
    #     obj = self.get_object(request, unquote(object_id))
    #
    #     if not self.has_change_permission(request, obj):
    #         raise PermissionDenied
    #
    #     if obj is None:
    #         raise Http404(_('%(name)s object with primary key %(key)r does not exist.') % {'name': force_text(opts.verbose_name), 'key': escape(object_id)})
    #
    #     if request.method == 'POST' and "_saveasnew" in request.POST:
    #         return self.add_view(request, form_url=reverse('admin:%s_%s_add' %
    #                                 (opts.app_label, opts.model_name),
    #                                 current_app=self.admin_site.name))
    #
    #     ModelForm = self.get_form(request, obj)
    #     formsets = []
    #     inline_instances = self.get_inline_instances(request, obj)
    #     if request.method == 'POST':
    #         form = ModelForm(request.POST, request.FILES, instance=obj)
    #         if form.is_valid():
    #             form_validated = True
    #             new_object = self.save_form(request, form, change=True)
    #         else:
    #             form_validated = False
    #             new_object = obj
    #         prefixes = {}
    #         for FormSet, inline in zip(self.get_formsets(request, new_object), inline_instances):
    #             prefix = FormSet.get_default_prefix()
    #             prefixes[prefix] = prefixes.get(prefix, 0) + 1
    #             if prefixes[prefix] != 1 or not prefix:
    #                 prefix = "%s-%s" % (prefix, prefixes[prefix])
    #             formset = FormSet(request.POST, request.FILES,
    #                               instance=new_object, prefix=prefix,
    #                               queryset=inline.get_queryset(request))
    #
    #             formsets.append(formset)
    #
    #         if all_valid(formsets) and form_validated:
    #
    #             # Here is the modified code.
    #
    #             for formset, inline in zip(formsets, self.get_inline_instances(request)):
    #                 if not isinstance(inline, ReverseInlineModelAdmin):
    #                     continue
    #                 objects = formset.save()
    #                 if len(objects)==1:
    #                     setattr(new_object, inline.parent_fk_name, objects[0])
    #             # End modified code
    #
    #
    #             self.save_model(request, new_object, form, True)
    #             self.save_related(request, form, formsets, True)
    #             change_message = self.construct_change_message(request, form, formsets)
    #             self.log_change(request, new_object, change_message)
    #             return self.response_change(request, new_object)
    #
    #     else:
    #         form = ModelForm(instance=obj)
    #         prefixes = {}
    #         for FormSet, inline in zip(self.get_formsets(request, obj), inline_instances):
    #             prefix = FormSet.get_default_prefix()
    #             prefixes[prefix] = prefixes.get(prefix, 0) + 1
    #             if prefixes[prefix] != 1 or not prefix:
    #                 prefix = "%s-%s" % (prefix, prefixes[prefix])
    #             formset = FormSet(instance=obj, prefix=prefix,
    #                               queryset=inline.get_queryset(request))
    #             formsets.append(formset)
    #
    #     adminForm = helpers.AdminForm(form, self.get_fieldsets(request, obj),
    #         self.get_prepopulated_fields(request, obj),
    #         self.get_readonly_fields(request, obj),
    #         model_admin=self)
    #     media = self.media + adminForm.media
    #
    #     inline_admin_formsets = []
    #     for inline, formset in zip(inline_instances, formsets):
    #         fieldsets = list(inline.get_fieldsets(request, obj))
    #         readonly = list(inline.get_readonly_fields(request, obj))
    #         prepopulated = dict(inline.get_prepopulated_fields(request, obj))
    #         inline_admin_formset = helpers.InlineAdminFormSet(inline, formset,
    #             fieldsets, prepopulated, readonly, model_admin=self)
    #         inline_admin_formsets.append(inline_admin_formset)
    #         media = media + inline_admin_formset.media
    #
    #     context = {
    #         'title': _('Change %s') % force_text(opts.verbose_name),
    #         'adminform': adminForm,
    #         'object_id': object_id,
    #         'original': obj,
    #         'is_popup': IS_POPUP_VAR in request.REQUEST,
    #         'media': media,
    #         'inline_admin_formsets': inline_admin_formsets,
    #         'errors': helpers.AdminErrorList(form, formsets),
    #         'app_label': opts.app_label,
    #         'preserved_filters': self.get_preserved_filters(request),
    #     }
    #     context.update(extra_context or {})
    #     return self.render_change_form(request, context, change=True, obj=obj, form_url=form_url)
    #

Tested and working wonderfully. I got it working with fieldsets too: https://gist.github.com/andybak/80e860673485f5ffdb08