Properly validate unique_together. (fixes inueni#7).

Author: sect2k

.gitignore

@@ -1,6 +1,7 @@
 .DS_Store
 *.pyc
 .vscode
+.python-version
 /dist
 /*.egg-info
 /build

README.md

@@ -80,6 +80,14 @@ admin.site.register(MailingList, MailingListAdmin)
 
 With just a few lines of code you get a fully functional `ModelAdmin`, that will automatically pull in just the relevant related objects, based on `ForeignKey` relation between the two models, it will also auto set `ForeignKey` fields for nested relations and exclude them from change form when adding and editing objects on subadmin.
 
+
+### Caveats
+
+In order to properly support unique field validation (see #7), `SubAdmin` will inject a small mixin into the form. This is done in the `get_form` method and if you override this method in your own classes, make sure to call `super()` or `perp_subadmin_form()` directly. See `subadmin` source code for more details.
+
+Also, the injected mixin `SubAdminFormMixin` overrides `validate_unique` on the form. If your custom form overrides this method as well, have a look at `subadmin` source code for ways in which it differs from stock `ModelForm` implementation.
+
+
 ### Screenshots
 
 ![alt text](https://github.com/inueni/django-subadmin-example/raw/master/screenshots/subadmin_screenshot_1.png?raw=true)
@@ -100,7 +108,6 @@ When adding or editing objects with `SubAdmin`, `ForeignKey` fields to parent in
 
 > If you want to see it in action, or get a more in-depth look at how to set everything up, check out <https://github.com/inueni/django-subadmin-example>.
 
-
 ## Stability
 
 `django-subadmin` has evolved from code that has been running on production servers since early 2014 without any issues. The code is provided **as-is** and the developers bear no responsibility for any issues stemming from it's use.

subadmin/__init__.py

@@ -4,6 +4,7 @@
 from urllib.parse import parse_qsl, urlparse, urlunparse
 
 from django.urls import path, re_path, include
+from django.core.exceptions import ValidationError
 from django.contrib.admin.options import IS_POPUP_VAR, TO_FIELD_VAR
 from django.contrib.admin.utils import unquote, quote
 from django.contrib import admin
@@ -14,19 +15,18 @@
 from django.forms.models import _get_foreign_key
 from django.http import HttpResponseRedirect
 from django.shortcuts import get_object_or_404
-from django.template.response import SimpleTemplateResponse, TemplateResponse
+from django.template.response import TemplateResponse
 from django.utils.decorators import method_decorator
 from django.utils.functional import cached_property
 from django.utils.html import format_html
 from django.utils.http import urlencode, urlquote
 from django.utils.translation import ugettext as _
 from django.views.decorators.csrf import csrf_protect
 from django.urls import Resolver404, get_script_prefix, resolve, reverse
-from .forms import get_form
 
 csrf_protect_m = method_decorator(csrf_protect)
 
-__all__ = ('SubAdmin', 'RootSubAdmin', 'SubAdminMixin', 'RootSubAdminMixin', 'SubAdminChangeList', 'SubAdminHelper')
+__all__ = ('SubAdmin', 'RootSubAdmin', 'SubAdminMixin', 'RootSubAdminMixin', 'SubAdminChangeList', 'SubAdminHelper', 'SubAdminFormMixin')
 
 
 class SubAdminHelper(object):
@@ -87,6 +87,38 @@ def url_for_result(self, result):
         return self.model_admin.reverse_url('change', *self.model_admin.get_base_url_args(self.request) + [pk])
 
 
+class SubAdminFormMixin(object):
+    def _post_clean(self):
+        validate_unique = self._validate_unique
+        self._validate_unique = False
+        super()._post_clean()
+
+        for fk_field, fk_instance in self._related_instances_fields.items():
+            setattr(self.instance, fk_field, fk_instance)
+
+        self._validate_unique = validate_unique
+        if self._validate_unique:
+            self.validate_unique()
+
+        
+    def validate_unique(self):
+        exclude = self._get_subadmin_validation_exclusions()
+
+        try:
+            self.instance.validate_unique(exclude=exclude)
+        except ValidationError as e:
+            self._update_errors(e)
+
+    def _get_subadmin_validation_exclusions(self):
+        return [f for f in self._get_validation_exclusions() if f not in self._related_instances_fields.keys()]
+
+    @cached_property
+    def _related_instances_fields(self):
+        return {
+            key: self._related_instances[key] for key in self._related_instances.keys() if key in self._meta.model._meta._forward_fields_map.keys()
+        }
+
+
 class SubAdminBase(object):
     subadmins = None
 
@@ -198,13 +230,17 @@ def get_exclude(self, request, obj=None):
         exclude.extend(request.subadmin.related_instances.keys())
         return list(set(exclude))
 
+    def prep_subadmin_form(self, request, form):
+        attrs = {'_related_instances': request.subadmin.related_instances}
+        return type(form)(form.__name__, (SubAdminFormMixin, form), attrs)
+
+    def get_form(self, request, obj=None, **kwargs):
+        form = super().get_form(request, obj, **kwargs)
+        return self.prep_subadmin_form(request, form)
+
     def get_changelist_form(self, request, **kwargs):
         form = super().get_changelist_form(request, **kwargs)
-        return get_form(form, self.model, request.subadmin.related_instances)
-
-    def get_form(self, request, obj=None, change=False, **kwargs):
-        form = super().get_form(request, obj, change, **kwargs)
-        return get_form(form, self.model, request.subadmin.related_instances)
+        return self.prep_subadmin_form(request, form)
 
     def get_base_viewname(self):
         if hasattr(self.parent_admin, 'get_base_viewname'):
@@ -408,7 +444,11 @@ def response_change(self, request, obj):
                 'obj': str(obj),
                 'new_value': str(new_value),
             })
-            return SimpleTemplateResponse('admin/popup_response.html', {
+            return TemplateResponse(request, self.popup_response_template or [
+                'admin/%s/%s/popup_response.html' % (opts.app_label, opts.model_name),
+                'admin/%s/popup_response.html' % opts.app_label,
+                'admin/popup_response.html',
+            ], {
                 'popup_response_data': popup_response_data,
             })
 
@@ -487,7 +527,11 @@ def response_delete(self, request, obj_display, obj_id):
                 'action': 'delete',
                 'value': str(obj_id),
             })
-            return SimpleTemplateResponse('admin/popup_response.html', {
+            return TemplateResponse(request, self.popup_response_template or [
+                'admin/%s/%s/popup_response.html' % (opts.app_label, opts.model_name),
+                'admin/%s/popup_response.html' % opts.app_label,
+                'admin/popup_response.html',
+            ], {
                 'popup_response_data': popup_response_data,
             })