From 42e175392e1248184e3addeccc4081ebb62bb45b Mon Sep 17 00:00:00 2001
From: Tim Heap <tim@timheap.me>
Date: Tue, 22 Jul 2014 17:11:58 +1000
Subject: [PATCH 1/9] Implement `Page.parent_page_types`

Similar to `Page.subpage_types`, but restricts which pages can have a
specific page type as a child.

Useful for Blog posts being restricted to Blog list pages, or similar
things.
---
 wagtail/wagtailadmin/views/pages.py |  2 +-
 wagtail/wagtailcore/models.py       | 78 +++++++++++++++++++++--------
 wagtail/wagtailcore/utils.py        | 28 +++++++++++
 3 files changed, 85 insertions(+), 23 deletions(-)

diff --git a/wagtail/wagtailadmin/views/pages.py b/wagtail/wagtailadmin/views/pages.py
index a7212cc3e2..20ddead472 100644
--- a/wagtail/wagtailadmin/views/pages.py
+++ b/wagtail/wagtailadmin/views/pages.py
@@ -68,7 +68,7 @@ def add_subpage(request, parent_page_id):
     if not parent_page.permissions_for_user(request.user).can_add_subpage():
         raise PermissionDenied
 
-    page_types = sorted(parent_page.clean_subpage_types(), key=lambda pagetype: pagetype.name.lower())
+    page_types = sorted(parent_page.allowed_subpage_types(), key=lambda pagetype: pagetype.name.lower())
 
     if len(page_types) == 1:
         # Only one page type is available - redirect straight to the create form rather than
diff --git a/wagtail/wagtailcore/models.py b/wagtail/wagtailcore/models.py
index 3db7a71a0e..9ce0061447 100644
--- a/wagtail/wagtailcore/models.py
+++ b/wagtail/wagtailcore/models.py
@@ -8,7 +8,7 @@ from six.moves.urllib.parse import urlparse
 from modelcluster.models import ClusterableModel, get_all_child_relations
 
 from django.db import models, connection, transaction
-from django.db.models import get_model, Q
+from django.db.models import Q
 from django.http import Http404
 from django.core.cache import cache
 from django.core.handlers.wsgi import WSGIRequest
@@ -26,7 +26,7 @@ from django.utils.encoding import python_2_unicode_compatible
 
 from treebeard.mp_tree import MP_Node
 
-from wagtail.wagtailcore.utils import camelcase_to_underscore
+from wagtail.wagtailcore.utils import camelcase_to_underscore, resolve_model_string
 from wagtail.wagtailcore.query import PageQuerySet
 from wagtail.wagtailcore.url_routing import RouteResult
 
@@ -236,6 +236,7 @@ class PageBase(models.base.ModelBase):
             cls.ajax_template = None
 
         cls._clean_subpage_types = None  # to be filled in on first call to cls.clean_subpage_types
+        cls._clean_parent_page_types = None  # to be filled in on first call to cls.clean_parent_page_types
 
         if not dct.get('is_abstract'):
             # subclasses are only abstract if the subclass itself defines itself so
@@ -513,36 +514,62 @@ class Page(six.with_metaclass(PageBase, MP_Node, ClusterableModel, index.Indexed
                 # if subpage_types is not specified on the Page class, allow all page types as subpages
                 res = get_page_types()
             else:
-                res = []
-                for page_type in cls.subpage_types:
-                    if isinstance(page_type, string_types):
-                        try:
-                            app_label, model_name = page_type.split(".")
-                        except ValueError:
-                            # If we can't split, assume a model in current app
-                            app_label = cls._meta.app_label
-                            model_name = page_type
-
-                        model = get_model(app_label, model_name)
-                        if model:
-                            res.append(ContentType.objects.get_for_model(model))
-                        else:
-                            raise NameError(_("name '{0}' (used in subpage_types list) is not defined.").format(page_type))
-
-                    else:
-                        # assume it's already a model class
-                        res.append(ContentType.objects.get_for_model(page_type))
+                try:
+                    models = [resolve_model_string(model_string, cls._meta.app_label)
+                              for model_string in subpage_types]
+                except (NameError,) as err:
+                    raise NameError(err.args[0] + ' (used in subpage_types')
+                res = map(ContentType.objects.get_for_model, models)
 
             cls._clean_subpage_types = res
 
         return cls._clean_subpage_types
 
+    @classmethod
+    def clean_parent_page_types(cls):
+        """
+            Returns the list of parent page types, with strings converted to
+            class objects where required
+        """
+        if cls._clean_parent_page_types is None:
+            parent_page_types = getattr(cls, 'parent_page_types', None)
+            if parent_page_types is None:
+                # if parent_page_types is not specified on the Page class, allow all page types as subpages
+                res = get_page_types()
+            else:
+                try:
+                    models = [resolve_model_string(model_string, cls._meta.app_label)
+                              for model_string in parent_page_types]
+                except NameError as err:
+                    raise NameError(err.args[0] + ' (used in parent_page_types)')
+                res = map(ContentType.objects.get_for_model, models)
+
+            cls._clean_parent_page_types = res
+
+        return cls._clean_parent_page_types
+
     @classmethod
     def allowed_parent_page_types(cls):
         """
             Returns the list of page types that this page type can be a subpage of
         """
-        return [ct for ct in get_page_types() if cls in ct.model_class().clean_subpage_types()]
+        cls_ct = ContentType.objects.get_for_model(cls)
+        return [ct for ct in cls.clean_parent_page_types()
+                if cls_ct in ct.model_class().clean_subpage_types()]
+
+    @classmethod
+    def allowed_subpage_types(cls):
+        """
+            Returns the list of page types that this page type can be a subpage of
+        """
+        # Special case the 'Page' class, such as the Root page or Home page -
+        # otherwise you can not add initial pages when setting up a site
+        if cls == Page:
+            return get_page_types()
+
+        cls_ct = ContentType.objects.get_for_model(cls)
+        return [ct for ct in cls.clean_subpage_types()
+                if cls_ct in ct.model_class().clean_parent_page_types()]
 
     @classmethod
     def allowed_parent_pages(cls):
@@ -551,6 +578,13 @@ class Page(six.with_metaclass(PageBase, MP_Node, ClusterableModel, index.Indexed
         """
         return Page.objects.filter(content_type__in=cls.allowed_parent_page_types())
 
+    @classmethod
+    def allowed_subpages(cls):
+        """
+            Returns the list of pages that this page type can be a parent page of
+        """
+        return Page.objects.filter(content_type__in=cls.allowed_subpage_types())
+
     @classmethod
     def get_verbose_name(cls):
         """
diff --git a/wagtail/wagtailcore/utils.py b/wagtail/wagtailcore/utils.py
index c5ad7ea8da..37691f547e 100644
--- a/wagtail/wagtailcore/utils.py
+++ b/wagtail/wagtailcore/utils.py
@@ -1,6 +1,34 @@
 import re
+from django.db.models import Model, get_model
+from django.utils.translation import ugettext_lazy as _
+from six import string_types
 
 
 def camelcase_to_underscore(str):
     # http://djangosnippets.org/snippets/585/
     return re.sub('(((?<=[a-z])[A-Z])|([A-Z](?![A-Z]|$)))', '_\\1', str).lower().strip('_')
+
+
+def resolve_model_string(model_string, default_app):
+    """
+        Resolve an 'app_label.model_name' string in to an actual model class.
+        If a model class is passed in, just return that.
+    """
+    if isinstance(model_string, string_types):
+        try:
+            app_label, model_name = model_string.split(".")
+        except ValueError:
+            # If we can't split, assume a model in current app
+            app_label = default_app
+            model_name = model_string
+
+        model = get_model(app_label, model_name)
+        if not model:
+            raise NameError(_("name '{0}' is not defined.").format(model_string))
+        return model
+
+    elif issubclass(model_string, Model):
+        return model
+
+    else:
+        raise ValueError(_("Can not resolve '{0!r}' in to a model").format(model_string))

From 4bcacfabf24df6c52f5f2b1dfeb8fd1013d94883 Mon Sep 17 00:00:00 2001
From: Tim Heap <tim@timheap.me>
Date: Wed, 23 Jul 2014 12:25:07 +1000
Subject: [PATCH 2/9] Add tests for new `Page.parent_page_types` setting

---
 wagtail/tests/models.py                       | 12 ++++++-
 .../wagtailadmin/tests/test_pages_views.py    | 31 +++++++++++++------
 2 files changed, 33 insertions(+), 10 deletions(-)

diff --git a/wagtail/tests/models.py b/wagtail/tests/models.py
index c708c452b8..66709b8978 100644
--- a/wagtail/tests/models.py
+++ b/wagtail/tests/models.py
@@ -376,7 +376,9 @@ class ZuluSnippet(models.Model):
 
 
 class StandardIndex(Page):
-    pass
+    """ Index for the site, not allowed to be placed anywhere """
+    parent_page_types = []
+
 
 StandardIndex.content_panels = [
     FieldPanel('title', classname="full title"),
@@ -387,14 +389,22 @@ StandardIndex.content_panels = [
 class StandardChild(Page):
     pass
 
+
 class BusinessIndex(Page):
+    """ Can be placed anywhere, can only have Business children """
     subpage_types = ['tests.BusinessChild', 'tests.BusinessSubIndex']
 
+
 class BusinessSubIndex(Page):
+    """ Can be placed under BusinessIndex, and have BusinessChild children """
     subpage_types = ['tests.BusinessChild']
+    parent_page_types = ['tests.BusinessIndex']
+
 
 class BusinessChild(Page):
+    """ Can only be placed under Business indexes, no children allowed """
     subpage_types = []
+    parent_page_types = ['tests.BusinessIndex', 'tests.BusinessSubIndex']
 
 
 class SearchTest(models.Model, index.Indexed):
diff --git a/wagtail/wagtailadmin/tests/test_pages_views.py b/wagtail/wagtailadmin/tests/test_pages_views.py
index ab231cc7ea..eb7668a6d9 100644
--- a/wagtail/wagtailadmin/tests/test_pages_views.py
+++ b/wagtail/wagtailadmin/tests/test_pages_views.py
@@ -8,7 +8,11 @@ from django.core import mail
 from django.core.paginator import Paginator
 from django.utils import timezone
 
-from wagtail.tests.models import SimplePage, EventPage, EventPageCarouselItem, StandardIndex, BusinessIndex, BusinessChild, BusinessSubIndex, TaggedPage, Advert, AdvertPlacement
+from wagtail.tests.models import (
+    SimplePage, EventPage, EventPageCarouselItem,
+    StandardIndex, StandardChild,
+    BusinessIndex, BusinessChild, BusinessSubIndex,
+    TaggedPage, Advert, AdvertPlacement)
 from wagtail.tests.utils import unittest, WagtailTestUtils
 from wagtail.wagtailcore.models import Page, PageRevision
 from wagtail.wagtailcore.signals import page_published, page_unpublished
@@ -1483,11 +1487,14 @@ class TestSubpageBusinessRules(TestCase, WagtailTestUtils):
         self.assertEqual(response.status_code, 200)
         self.assertContains(response, add_subpage_url)
 
-        # add_subpage should give us the full set of page types to choose
+        # add_subpage should give us choices of StandardChild, and BusinessIndex.
+        # BusinessSubIndex and BusinessChild are not allowed
         response = self.client.get(add_subpage_url)
         self.assertEqual(response.status_code, 200)
-        self.assertContains(response, 'Standard Child')
-        self.assertContains(response, 'Business Child')
+        self.assertContains(response, StandardChild.get_verbose_name())
+        self.assertContains(response, BusinessIndex.get_verbose_name())
+        self.assertNotContains(response, BusinessSubIndex.get_verbose_name())
+        self.assertNotContains(response, BusinessChild.get_verbose_name())
 
     def test_business_subpage(self):
         add_subpage_url = reverse('wagtailadmin_pages_add_subpage', args=(self.business_index.id, ))
@@ -1500,8 +1507,10 @@ class TestSubpageBusinessRules(TestCase, WagtailTestUtils):
         # add_subpage should give us a cut-down set of page types to choose
         response = self.client.get(add_subpage_url)
         self.assertEqual(response.status_code, 200)
-        self.assertNotContains(response, 'Standard Child')
-        self.assertContains(response, 'Business Child')
+        self.assertNotContains(response, StandardIndex.get_verbose_name())
+        self.assertNotContains(response, StandardChild.get_verbose_name())
+        self.assertContains(response, BusinessSubIndex.get_verbose_name())
+        self.assertContains(response, BusinessChild.get_verbose_name())
 
     def test_business_child_subpage(self):
         add_subpage_url = reverse('wagtailadmin_pages_add_subpage', args=(self.business_child.id, ))
@@ -1516,12 +1525,16 @@ class TestSubpageBusinessRules(TestCase, WagtailTestUtils):
         self.assertEqual(response.status_code, 403)
 
     def test_cannot_add_invalid_subpage_type(self):
-        # cannot add SimplePage as a child of BusinessIndex, as SimplePage is not present in subpage_types
-        response = self.client.get(reverse('wagtailadmin_pages_create', args=('tests', 'simplepage', self.business_index.id)))
+        # cannot add StandardChild as a child of BusinessIndex, as StandardChild is not present in subpage_types
+        response = self.client.get(reverse('wagtailadmin_pages_create', args=('tests', 'standardchild', self.business_index.id)))
         self.assertEqual(response.status_code, 403)
 
         # likewise for BusinessChild which has an empty subpage_types list
-        response = self.client.get(reverse('wagtailadmin_pages_create', args=('tests', 'simplepage', self.business_child.id)))
+        response = self.client.get(reverse('wagtailadmin_pages_create', args=('tests', 'standardchild', self.business_child.id)))
+        self.assertEqual(response.status_code, 403)
+
+        # cannot add BusinessChild to StandardIndex, as BusinessChild restricts is parent page types
+        response = self.client.get(reverse('wagtailadmin_pages_create', args=('tests', 'businesschild', self.standard_index.id)))
         self.assertEqual(response.status_code, 403)
 
         # but we can add a BusinessChild to BusinessIndex

From 9aae3a1a23062ae763c66ef413746d9fd14e59dd Mon Sep 17 00:00:00 2001
From: Tim Heap <tim@timheap.me>
Date: Wed, 23 Jul 2014 12:29:00 +1000
Subject: [PATCH 3/9] Restrict child page types when creating them

The list of allowed child page types was restricted, but if you could
guess the URL to create a disallowed page type, nothing would stop you
creating it. Fixes a failing test case.
---
 wagtail/wagtailadmin/views/pages.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/wagtail/wagtailadmin/views/pages.py b/wagtail/wagtailadmin/views/pages.py
index 20ddead472..53810fa3cc 100644
--- a/wagtail/wagtailadmin/views/pages.py
+++ b/wagtail/wagtailadmin/views/pages.py
@@ -136,7 +136,7 @@ def create(request, content_type_app_name, content_type_model_name, parent_page_
         raise Http404
 
     # page must be in the list of allowed subpage types for this parent ID
-    if content_type not in parent_page.clean_subpage_types():
+    if content_type not in parent_page.allowed_subpage_types():
         raise PermissionDenied
 
     page = page_class(owner=request.user)

From 7b89f283db0932c98031a7caf875b8be52b48dd5 Mon Sep 17 00:00:00 2001
From: Tim Heap <tim@timheap.me>
Date: Wed, 23 Jul 2014 16:45:12 +1000
Subject: [PATCH 4/9] Force `Page._clean_sub/parent_page_types` to be a list

---
 wagtail/wagtailcore/models.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/wagtail/wagtailcore/models.py b/wagtail/wagtailcore/models.py
index 9ce0061447..65d2930d27 100644
--- a/wagtail/wagtailcore/models.py
+++ b/wagtail/wagtailcore/models.py
@@ -519,7 +519,7 @@ class Page(six.with_metaclass(PageBase, MP_Node, ClusterableModel, index.Indexed
                               for model_string in subpage_types]
                 except (NameError,) as err:
                     raise NameError(err.args[0] + ' (used in subpage_types')
-                res = map(ContentType.objects.get_for_model, models)
+                res = list(map(ContentType.objects.get_for_model, models))
 
             cls._clean_subpage_types = res
 
@@ -542,7 +542,7 @@ class Page(six.with_metaclass(PageBase, MP_Node, ClusterableModel, index.Indexed
                               for model_string in parent_page_types]
                 except NameError as err:
                     raise NameError(err.args[0] + ' (used in parent_page_types)')
-                res = map(ContentType.objects.get_for_model, models)
+                res = list(map(ContentType.objects.get_for_model, models))
 
             cls._clean_parent_page_types = res
 

From 96e907989080bed7d35544dee6376a3a3fc277f4 Mon Sep 17 00:00:00 2001
From: Tim Heap <tim@timheap.me>
Date: Thu, 24 Jul 2014 10:40:39 +1000
Subject: [PATCH 5/9] Add `Page.parent_page_types` to the docs

---
 docs/core_components/pages/theory.rst | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/docs/core_components/pages/theory.rst b/docs/core_components/pages/theory.rst
index bcea079bb4..f4929f2926 100644
--- a/docs/core_components/pages/theory.rst
+++ b/docs/core_components/pages/theory.rst
@@ -52,7 +52,7 @@ A Parent node could provide its own function returning its descendant objects.
 
             return events
 
-This example makes sure to limit the returned objects to pieces of content which make sense, specifically ones which have been published through Wagtail's admin interface (``live()``) and are children of this node (``descendant_of(self)``). By setting a ``subpage_types`` class property in your model, you can specify which models are allowed to be set as children, but Wagtail will allow any ``Page``-derived model by default. Regardless, it's smart for a parent model to provide an index filtered to make sense.
+This example makes sure to limit the returned objects to pieces of content which make sense, specifically ones which have been published through Wagtail's admin interface (``live()``) and are children of this node (``descendant_of(self)``). By setting a ``subpage_types`` class property in your model, you can specify which models are allowed to be set as children, and by settings a ``parent_page_types`` class property, you can specify which models are allowed to parent certain children. Wagtail will allow any ``Page``-derived model by default. Regardless, it's smart for a parent model to provide an index filtered to make sense.
 
 
 Leaves
@@ -71,7 +71,7 @@ The model for the leaf could provide a function that traverses the tree in the o
             # Find closest ancestor which is an event index
             return self.get_ancestors().type(EventIndexPage).last()
 
-If defined, ``subpage_types`` will also limit the parent models allowed to contain a leaf. If not, Wagtail will allow any combination of parents and leafs to be associated in the Wagtail tree. Like with index pages, it's a good idea to make sure that the index is actually of the expected model to contain the leaf.
+If defined, ``subpage_types`` and ``parent_page_types`` will also limit the parent models allowed to contain a leaf. If not, Wagtail will allow any combination of parents and leafs to be associated in the Wagtail tree. Like with index pages, it's a good idea to make sure that the index is actually of the expected model to contain the leaf.
 
 
 Other Relationships

From 18909c834f11e5a1682c56088bd40daffb49aa74 Mon Sep 17 00:00:00 2001
From: Tim Heap <tim@timheap.me>
Date: Thu, 24 Jul 2014 10:49:30 +1000
Subject: [PATCH 6/9] Replace all calls to clean_subpage_types with
 allowed_subpage_types

`clean_subpage_types` should not be part of the public API any more, and
`allowed_subpage_types` should replace it in all instances.
---
 wagtail/wagtailcore/models.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/wagtail/wagtailcore/models.py b/wagtail/wagtailcore/models.py
index 65d2930d27..dd1bdb52c0 100644
--- a/wagtail/wagtailcore/models.py
+++ b/wagtail/wagtailcore/models.py
@@ -1057,7 +1057,7 @@ class PagePermissionTester(object):
     def can_add_subpage(self):
         if not self.user.is_active:
             return False
-        if not self.page.specific_class.clean_subpage_types():  # this page model has an empty subpage_types list, so no subpages are allowed
+        if not self.page.specific_class.allowed_subpage_types():  # this page model has an empty subpage_types list, so no subpages are allowed
             return False
         return self.user.is_superuser or ('add' in self.permissions)
 
@@ -1121,7 +1121,7 @@ class PagePermissionTester(object):
         """
         if not self.user.is_active:
             return False
-        if not self.page.specific_class.clean_subpage_types():  # this page model has an empty subpage_types list, so no subpages are allowed
+        if not self.page.specific_class.allowed_subpage_types():  # this page model has an empty subpage_types list, so no subpages are allowed
             return False
 
         return self.user.is_superuser or ('publish' in self.permissions)

From 999b052fe5b674f2928b67cb91762b16e4d5b137 Mon Sep 17 00:00:00 2001
From: Tim Heap <tim@timheap.me>
Date: Fri, 22 Aug 2014 09:18:00 +1000
Subject: [PATCH 7/9] Fix indentation of docstings

---
 wagtail/wagtailcore/models.py | 34 +++++++++++++++++-----------------
 wagtail/wagtailcore/utils.py  |  4 ++--
 2 files changed, 19 insertions(+), 19 deletions(-)

diff --git a/wagtail/wagtailcore/models.py b/wagtail/wagtailcore/models.py
index dd1bdb52c0..1fa436014a 100644
--- a/wagtail/wagtailcore/models.py
+++ b/wagtail/wagtailcore/models.py
@@ -58,15 +58,15 @@ class Site(models.Model):
     @staticmethod
     def find_for_request(request):
         """
-            Find the site object responsible for responding to this HTTP
-            request object. Try:
-             - unique hostname first
-             - then hostname and port
-             - if there is no matching hostname at all, or no matching
-               hostname:port combination, fall back to the unique default site,
-               or raise an exception
-            NB this means that high-numbered ports on an extant hostname may
-            still be routed to a different hostname which is set as the default
+        Find the site object responsible for responding to this HTTP
+        request object. Try:
+         - unique hostname first
+         - then hostname and port
+         - if there is no matching hostname at all, or no matching
+           hostname:port combination, fall back to the unique default site,
+           or raise an exception
+        NB this means that high-numbered ports on an extant hostname may
+        still be routed to a different hostname which is set as the default
         """
         try:
             hostname = request.META['HTTP_HOST'].split(':')[0] # KeyError here goes to the final except clause
@@ -505,8 +505,8 @@ class Page(six.with_metaclass(PageBase, MP_Node, ClusterableModel, index.Indexed
     @classmethod
     def clean_subpage_types(cls):
         """
-            Returns the list of subpage types, with strings converted to class objects
-            where required
+        Returns the list of subpage types, with strings converted to class objects
+        where required
         """
         if cls._clean_subpage_types is None:
             subpage_types = getattr(cls, 'subpage_types', None)
@@ -528,8 +528,8 @@ class Page(six.with_metaclass(PageBase, MP_Node, ClusterableModel, index.Indexed
     @classmethod
     def clean_parent_page_types(cls):
         """
-            Returns the list of parent page types, with strings converted to
-            class objects where required
+        Returns the list of parent page types, with strings converted to class
+        objects where required
         """
         if cls._clean_parent_page_types is None:
             parent_page_types = getattr(cls, 'parent_page_types', None)
@@ -551,7 +551,7 @@ class Page(six.with_metaclass(PageBase, MP_Node, ClusterableModel, index.Indexed
     @classmethod
     def allowed_parent_page_types(cls):
         """
-            Returns the list of page types that this page type can be a subpage of
+        Returns the list of page types that this page type can be a subpage of
         """
         cls_ct = ContentType.objects.get_for_model(cls)
         return [ct for ct in cls.clean_parent_page_types()
@@ -560,7 +560,7 @@ class Page(six.with_metaclass(PageBase, MP_Node, ClusterableModel, index.Indexed
     @classmethod
     def allowed_subpage_types(cls):
         """
-            Returns the list of page types that this page type can be a subpage of
+        Returns the list of page types that this page type can be a subpage of
         """
         # Special case the 'Page' class, such as the Root page or Home page -
         # otherwise you can not add initial pages when setting up a site
@@ -574,14 +574,14 @@ class Page(six.with_metaclass(PageBase, MP_Node, ClusterableModel, index.Indexed
     @classmethod
     def allowed_parent_pages(cls):
         """
-            Returns the list of pages that this page type can be a subpage of
+        Returns the list of pages that this page type can be a subpage of
         """
         return Page.objects.filter(content_type__in=cls.allowed_parent_page_types())
 
     @classmethod
     def allowed_subpages(cls):
         """
-            Returns the list of pages that this page type can be a parent page of
+        Returns the list of pages that this page type can be a parent page of
         """
         return Page.objects.filter(content_type__in=cls.allowed_subpage_types())
 
diff --git a/wagtail/wagtailcore/utils.py b/wagtail/wagtailcore/utils.py
index 37691f547e..52913bedac 100644
--- a/wagtail/wagtailcore/utils.py
+++ b/wagtail/wagtailcore/utils.py
@@ -11,8 +11,8 @@ def camelcase_to_underscore(str):
 
 def resolve_model_string(model_string, default_app):
     """
-        Resolve an 'app_label.model_name' string in to an actual model class.
-        If a model class is passed in, just return that.
+    Resolve an 'app_label.model_name' string in to an actual model class.
+    If a model class is passed in, just return that.
     """
     if isinstance(model_string, string_types):
         try:

From 7921abe924ed1c97ecf7df171c59f15983155b0e Mon Sep 17 00:00:00 2001
From: Tim Heap <tim@timheap.me>
Date: Fri, 22 Aug 2014 10:06:09 +1000
Subject: [PATCH 8/9] Fix errors raised with `resolve_model_string`

It now raises `ValueError` for a badly formatted string, and `NameError`
if it can not find the model. Error messages are not translated. Edit
handlers now use the function.
---
 wagtail/wagtailadmin/edit_handlers.py | 29 +++++++++------------------
 wagtail/wagtailcore/models.py         | 10 +++++----
 wagtail/wagtailcore/utils.py          | 20 ++++++++++--------
 3 files changed, 28 insertions(+), 31 deletions(-)

diff --git a/wagtail/wagtailadmin/edit_handlers.py b/wagtail/wagtailadmin/edit_handlers.py
index 3e463523d4..1c5ec6a098 100644
--- a/wagtail/wagtailadmin/edit_handlers.py
+++ b/wagtail/wagtailadmin/edit_handlers.py
@@ -19,8 +19,8 @@ from django.core.urlresolvers import reverse
 from django.utils.translation import ugettext_lazy
 
 from wagtail.wagtailcore.models import Page
-from wagtail.wagtailcore.utils import camelcase_to_underscore
 from wagtail.wagtailcore.fields import RichTextArea
+from wagtail.wagtailcore.utils import camelcase_to_underscore, resolve_model_string
 
 
 FORM_FIELD_OVERRIDES = {}
@@ -483,25 +483,16 @@ class BasePageChooserPanel(BaseChooserPanel):
     def target_content_type(cls):
         if cls._target_content_type is None:
             if cls.page_type:
-                if isinstance(cls.page_type, string_types):
-                    # translate the passed model name into an actual model class
-                    from django.db.models import get_model
-                    try:
-                        app_label, model_name = cls.page_type.split('.')
-                    except ValueError:
-                        raise ImproperlyConfigured("The page_type passed to PageChooserPanel must be of the form 'app_label.model_name'")
+                try:
+                    model = resolve_model_string(cls.page_type)
+                except NameError:
+                    raise ImproperlyConfigured("{0}.page_type must be of the form 'app_label.model_name', given {1!r}".format(
+                        cls.__name__, cls.page_type))
+                except ValueError:
+                    raise ImproperlyConfigured("{0}.page_type refers to model {1!r} that has not been installed".format(
+                        cls.__name__, cls.page_type))
 
-                    try:
-                        page_type = get_model(app_label, model_name)
-                    except LookupError:
-                        page_type = None
-
-                    if page_type is None:
-                        raise ImproperlyConfigured("PageChooserPanel refers to model '%s' that has not been installed" % cls.page_type)
-                else:
-                    page_type = cls.page_type
-
-                cls._target_content_type = ContentType.objects.get_for_model(page_type)
+                cls._target_content_type = ContentType.objects.get_for_model(model)
             else:
                 # TODO: infer the content type by introspection on the foreign key
                 cls._target_content_type = ContentType.objects.get_by_natural_key('wagtailcore', 'page')
diff --git a/wagtail/wagtailcore/models.py b/wagtail/wagtailcore/models.py
index 1fa436014a..6b13c61de6 100644
--- a/wagtail/wagtailcore/models.py
+++ b/wagtail/wagtailcore/models.py
@@ -20,7 +20,7 @@ from django.conf import settings
 from django.template.response import TemplateResponse
 from django.utils import timezone
 from django.utils.translation import ugettext_lazy as _
-from django.core.exceptions import ValidationError
+from django.core.exceptions import ValidationError, ImproperlyConfigured
 from django.utils.functional import cached_property
 from django.utils.encoding import python_2_unicode_compatible
 
@@ -517,8 +517,9 @@ class Page(six.with_metaclass(PageBase, MP_Node, ClusterableModel, index.Indexed
                 try:
                     models = [resolve_model_string(model_string, cls._meta.app_label)
                               for model_string in subpage_types]
-                except (NameError,) as err:
-                    raise NameError(err.args[0] + ' (used in subpage_types')
+                except NameError as err:
+                    raise ImproperlyConfigured("{0}.subpage_types must be a list of 'app_label.model_name' strings, given {1!r}".format(
+                        cls.__name__, err.args[1]))
                 res = list(map(ContentType.objects.get_for_model, models))
 
             cls._clean_subpage_types = res
@@ -541,7 +542,8 @@ class Page(six.with_metaclass(PageBase, MP_Node, ClusterableModel, index.Indexed
                     models = [resolve_model_string(model_string, cls._meta.app_label)
                               for model_string in parent_page_types]
                 except NameError as err:
-                    raise NameError(err.args[0] + ' (used in parent_page_types)')
+                    raise ImproperlyConfigured("{0}.parent_page_types must be a list of 'app_label.model_name' strings, given {1!r}".format(
+                        cls.__name__, err.args[1]))
                 res = list(map(ContentType.objects.get_for_model, models))
 
             cls._clean_parent_page_types = res
diff --git a/wagtail/wagtailcore/utils.py b/wagtail/wagtailcore/utils.py
index 52913bedac..d03d5ae756 100644
--- a/wagtail/wagtailcore/utils.py
+++ b/wagtail/wagtailcore/utils.py
@@ -1,6 +1,5 @@
 import re
 from django.db.models import Model, get_model
-from django.utils.translation import ugettext_lazy as _
 from six import string_types
 
 
@@ -9,7 +8,7 @@ def camelcase_to_underscore(str):
     return re.sub('(((?<=[a-z])[A-Z])|([A-Z](?![A-Z]|$)))', '_\\1', str).lower().strip('_')
 
 
-def resolve_model_string(model_string, default_app):
+def resolve_model_string(model_string, default_app=None):
     """
     Resolve an 'app_label.model_name' string in to an actual model class.
     If a model class is passed in, just return that.
@@ -18,17 +17,22 @@ def resolve_model_string(model_string, default_app):
         try:
             app_label, model_name = model_string.split(".")
         except ValueError:
-            # If we can't split, assume a model in current app
-            app_label = default_app
-            model_name = model_string
+            if default_app is not None:
+                # If we can't split, assume a model in current app
+                app_label = default_app
+                model_name = model_string
+            else:
+                raise ValueError("Can not resolve {0!r} in to a model. Model names "
+                                 "should be in the form app_label.model_name".format(
+                                     model_string), model_string)
 
         model = get_model(app_label, model_name)
         if not model:
-            raise NameError(_("name '{0}' is not defined.").format(model_string))
+            raise NameError("Can not resolve {0!r} in to a model".format(model_string), model_string)
         return model
 
-    elif issubclass(model_string, Model):
+    elif model_string is not None and issubclass(model_string, Model):
         return model
 
     else:
-        raise ValueError(_("Can not resolve '{0!r}' in to a model").format(model_string))
+        raise NameError("Can not resolve {0!r} in to a model".format(model_string), model_string)

From b8b79cd151f8c01bf1137e9ab148d62dffd2f2ea Mon Sep 17 00:00:00 2001
From: Tim Heap <tim@timheap.me>
Date: Fri, 5 Sep 2014 09:59:53 +1000
Subject: [PATCH 9/9] `resolve_model_string` now raises `LookupError`

Django 1.7 raises a `LookupError` when looking for a model that does not
exist. This brings the code in to line with Django. The `LookupError`
from Django is allowed to propagate in 1.7, and a `LookupError` is now
raised instead of a `NameError` in 1.6.

All code using `resolve_model_string` has been changed to catch the new
errors.
---
 wagtail/wagtailadmin/edit_handlers.py | 2 +-
 wagtail/wagtailcore/models.py         | 4 ++--
 wagtail/wagtailcore/utils.py          | 4 ++--
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/wagtail/wagtailadmin/edit_handlers.py b/wagtail/wagtailadmin/edit_handlers.py
index 1c5ec6a098..137bb207a4 100644
--- a/wagtail/wagtailadmin/edit_handlers.py
+++ b/wagtail/wagtailadmin/edit_handlers.py
@@ -485,7 +485,7 @@ class BasePageChooserPanel(BaseChooserPanel):
             if cls.page_type:
                 try:
                     model = resolve_model_string(cls.page_type)
-                except NameError:
+                except LookupError:
                     raise ImproperlyConfigured("{0}.page_type must be of the form 'app_label.model_name', given {1!r}".format(
                         cls.__name__, cls.page_type))
                 except ValueError:
diff --git a/wagtail/wagtailcore/models.py b/wagtail/wagtailcore/models.py
index 6b13c61de6..2c5bcaa158 100644
--- a/wagtail/wagtailcore/models.py
+++ b/wagtail/wagtailcore/models.py
@@ -517,7 +517,7 @@ class Page(six.with_metaclass(PageBase, MP_Node, ClusterableModel, index.Indexed
                 try:
                     models = [resolve_model_string(model_string, cls._meta.app_label)
                               for model_string in subpage_types]
-                except NameError as err:
+                except LookupError as err:
                     raise ImproperlyConfigured("{0}.subpage_types must be a list of 'app_label.model_name' strings, given {1!r}".format(
                         cls.__name__, err.args[1]))
                 res = list(map(ContentType.objects.get_for_model, models))
@@ -541,7 +541,7 @@ class Page(six.with_metaclass(PageBase, MP_Node, ClusterableModel, index.Indexed
                 try:
                     models = [resolve_model_string(model_string, cls._meta.app_label)
                               for model_string in parent_page_types]
-                except NameError as err:
+                except LookupError as err:
                     raise ImproperlyConfigured("{0}.parent_page_types must be a list of 'app_label.model_name' strings, given {1!r}".format(
                         cls.__name__, err.args[1]))
                 res = list(map(ContentType.objects.get_for_model, models))
diff --git a/wagtail/wagtailcore/utils.py b/wagtail/wagtailcore/utils.py
index d03d5ae756..403c79bf38 100644
--- a/wagtail/wagtailcore/utils.py
+++ b/wagtail/wagtailcore/utils.py
@@ -28,11 +28,11 @@ def resolve_model_string(model_string, default_app=None):
 
         model = get_model(app_label, model_name)
         if not model:
-            raise NameError("Can not resolve {0!r} in to a model".format(model_string), model_string)
+            raise LookupError("Can not resolve {0!r} in to a model".format(model_string), model_string)
         return model
 
     elif model_string is not None and issubclass(model_string, Model):
         return model
 
     else:
-        raise NameError("Can not resolve {0!r} in to a model".format(model_string), model_string)
+        raise LookupError("Can not resolve {0!r} in to a model".format(model_string), model_string)