Refactor forms.py: quite elegant and reusable Page _and_ Section forms. Both

work with the same edit.html template. Finally you can edit sections
individually!

cms/forms.py

@@ -10,12 +10,13 @@ Section = swapper.load_model('cms', 'Section')
 class PageForm(forms.ModelForm):
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
+        self.label_suffix = ''
         extra = 1 if self.instance.pk else 2
+
         self.formsets = [forms.inlineformset_factory(
             parent_model = Page,
             model = Section,
             form = SectionForm,
-            formset = BaseSectionFormSet,
             extra=extra,
         )(
             data=self.data if self.is_bound else None,
@@ -33,8 +34,6 @@ class PageForm(forms.ModelForm):
         super().clean()
         if not self.formsets[0].is_valid():
             self.add_error(None, _('There’s a problem saving one of the sections'))
-        if not self.instance and not self.formsets[0].has_changed():
-            self.add_error(None, _('You can’t save a new page without adding any sections!'))
 
     def save(self, *args, **kwargs):
         page = super().save()
@@ -55,18 +54,48 @@ class SectionForm(forms.ModelForm):
 
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
+        self.label_suffix = ''
+        self.fields['DELETE'] = forms.BooleanField(label=_('Delete'), required=False)
 
         # Repopulate the 'choices' attribute of the type field from
         # the child model.
         self.fields['type'].choices = self._meta.model.TYPES
         self.fields['type'].initial = self._meta.model.TYPES[0][0]
 
-    def delete(self):
-        instance = super().save()
-        instance.delete()
+        section = self.instance
+        self.formsets = []
+        for field in section._meta.get_fields():
+            if field.one_to_many:
+                extra = 1 if getattr(section, field.name).exists() else 2
+                formset = forms.inlineformset_factory(
+                    Section, field.related_model,
+                    fields='__all__',
+                    extra=extra,
+                )(
+                    instance=section,
+                    data=self.data if self.is_bound else None,
+                    files=self.files if self.is_bound else None,
+                    prefix=f'{self.prefix}-{field.name}',
+                    form_kwargs={'label_suffix': self.label_suffix},
+                )
+                formset.name = field.name
+                self.formsets.append(formset)
+
+    def is_valid(self):
+        result = super().is_valid()
+        if self.is_bound:
+            for formset in self.formsets:
+                result = result and formset.is_valid()
+        return result
 
     def save(self, commit=True):
-        section = super().save()
+        section = super().save(commit=commit)
+
+        if self.cleaned_data['DELETE']:
+            section.delete()
+            if section.page.slug and not section.page.sections.exists():
+                section.page.delete()
+            return
 
         # Explanation: get the content type of the model that the user
         # supplied when filling in this form, and save it's id to the
@@ -80,72 +109,15 @@ class SectionForm(forms.ModelForm):
 
         if commit:
             section.save()
+        for formset in self.formsets:
+            formset.save(commit=commit)
+
         return section
 
-    core_field_names = ['title', 'type', 'number', 'content', 'image', 'video', 'href']
-
-    def core_fields(self):
-        return [field for field in self.visible_fields() if field.name in self.core_field_names]
-
-    def extra_fields(self):
-        return [field for field in self.visible_fields() if field.name not in self.core_field_names]
-
     class Meta:
         model = Section
         exclude = ['page']
 
-class BaseSectionFormSet(forms.BaseInlineFormSet):
-    '''If a swappable Section model defines one-to-many fields, (i.e. has
-    foreign keys pointing to it) formsets will be generated for the
-    related models and stored in the form.formsets array.
-
-    Based on this logic for nested formsets:
-    https://www.yergler.net/2013/09/03/nested-formsets-redux/
-
-    Typical usecases could be:
-    - an images section that displays multiple images
-    - a column section that displays separate colums
-    - a calendar section that displays calendar events
-    - etc...
-
-    '''
-    def add_fields(self, form, index):
-        super().add_fields(form, index)
-        section = form.instance
-        form.formsets = []
-        for field in section._meta.get_fields():
-            if field.one_to_many:
-                extra = 1 if getattr(section, field.name).exists() else 2
-
-                formset = forms.inlineformset_factory(
-                    Section, field.related_model,
-                    fields='__all__',
-                    extra=extra,
-                )(
-                    instance=section,
-                    data=form.data if self.is_bound else None,
-                    files=form.files if self.is_bound else None,
-                    prefix=f'{form.prefix}-{field.name}',
-                    form_kwargs=self.form_kwargs,
-                )
-                formset.name = field.name
-                form.formsets.append(formset)
-
-    def is_valid(self):
-        result = super().is_valid()
-        if self.is_bound:
-            for form in self.forms:
-                for formset in form.formsets:
-                    result = result and formset.is_valid()
-        return result
-
-    def save(self, commit=True):
-        result = super().save(commit=commit)
-        for form in self:
-            for formset in form.formsets:
-                formset.save(commit=commit)
-        return result
-
 class ContactForm(forms.Form):
     sender = forms.EmailField(label=_('Your email address'))
     spam_protection = forms.CharField(label=_('Your message'), widget=forms.Textarea())

cms/models.py

@@ -22,11 +22,14 @@ class Numbered:
     def number_with_respect_to(self):
         return self.__class__.objects.all()
 
+    def get_field_name(self):
+        return self.__class__._meta.ordering[-1].lstrip('-')
+
     def _renumber(self):
         '''Renumbers the queryset while preserving the instance's number'''
 
         queryset = self.number_with_respect_to()
-        field_name = self.__class__._meta.ordering[-1].lstrip('-')
+        field_name = self.get_field_name()
         this_nr = getattr(self, field_name)
         if this_nr is None:
             this_nr = len(queryset) + 1
@@ -55,8 +58,9 @@ class Numbered:
         super().save(*args, **kwargs)
 
     def delete(self, *args, **kwargs):
-        super().delete(*args, **kwargs)
+        setattr(self, self.get_field_name(), 9999) # hack
         self._renumber()
+        super().delete(*args, **kwargs)
 
 class BasePage(Numbered, models.Model):
     '''Abstract base model for pages'''

cms/templates/cms/edit.html

@@ -98,6 +98,7 @@
     function setEventHandlers() {
         for (let typefield of document.querySelectorAll('select[name$=-type]')) {
             let formId = typefield.name.replace(/-type$/, '');
+            console.log(formId + 'huh');
             let form = document.getElementById(formId);
             let type = typefield.value.toLowerCase();
             showRelevantFields(form, type);

cms/urls.py

@@ -1,12 +1,15 @@
 from django.urls import path
-from .views import PageView, CreatePage, UpdatePage
+from .views import PageView, CreatePage, UpdatePage, CreateSection, UpdateSection
 
 app_name = 'cms'
 
 urlpatterns = [
     path('new/', CreatePage.as_view(), name='createpage'),
-    path('edit/', UpdatePage.as_view(), name='updatepage'),
+    path('edit/', UpdatePage.as_view(), kwargs={'slug': ''}, name='updatepage'),
+    path('edit/<int:number>/', UpdateSection.as_view(), kwargs={'slug': ''}, name='updatesection'),
     path('<slug:slug>/edit/', UpdatePage.as_view(), name='updatepage'),
+    path('<slug:slug>/edit/new/', CreateSection.as_view(), name='createsection'),
+    path('<slug:slug>/edit/<int:number>/', UpdateSection.as_view(), name='updatesection'),
     path('', PageView.as_view(), name='page'),
     path('<slug:slug>/', PageView.as_view(), name='page'),
 ]

cms/views.py

@@ -10,7 +10,7 @@ from django.contrib.contenttypes.models import ContentType
 from django.contrib.auth.mixins import UserPassesTestMixin
 
 from .decorators import register_view
-from .forms import PageForm
+from .forms import PageForm, SectionForm
 
 Page = swapper.load_model('cms', 'Page')
 Section = swapper.load_model('cms', 'Section')
@@ -143,16 +143,10 @@ class EditPage(UserPassesTestMixin, edit.ModelFormMixin, base.TemplateResponseMi
         app, model = swapper.get_model_name('cms', 'page').lower().split('.')
         return self.request.user.has_perm('f{app}_{model}_change')
 
-    def setup(self, *args, slug='', **kwargs):
-        '''Supply a default argument for slug'''
-        super().setup(*args, slug=slug, **kwargs)
-
     def get_form_kwargs(self):
         kwargs = super().get_form_kwargs()
-        kwargs.update({
-            'label_suffix': '',
-            'initial': {'slug': self.kwargs['slug']},
-        })
+        if 'slug' in self.kwargs:
+            kwargs.update({'initial': {'slug': self.kwargs['slug']}})
         return kwargs
 
     def get_context_data(self, **kwargs):
@@ -194,7 +188,77 @@ class EditPage(UserPassesTestMixin, edit.ModelFormMixin, base.TemplateResponseMi
 
 class CreatePage(EditPage):
     def get_object(self):
-        pass
+        return Page()
 
 class UpdatePage(EditPage):
     pass
+
+class EditSection(UserPassesTestMixin, edit.ModelFormMixin, base.TemplateResponseMixin, base.View):
+    model = Section
+    form_class = SectionForm
+    template_name = 'cms/edit.html'
+
+    def test_func(self):
+        app, model = swapper.get_model_name('cms', 'section').lower().split('.')
+        return self.request.user.has_perm('f{app}_{model}_change')
+
+    def get_form_kwargs(self):
+        kwargs = super().get_form_kwargs()
+        kwargs.update({
+            'prefix': 'section',
+        })
+        return kwargs
+
+    def get_context_data(self, **kwargs):
+        context = super().get_context_data(**kwargs)
+        fields_per_type = {}
+        for model, _ in Section.TYPES:
+            ctype = ContentType.objects.get(
+                app_label = Section._meta.app_label,
+                model = model.lower(),
+            )
+            fields_per_type[ctype.model] = ['type', 'number'] + ctype.model_class().fields
+
+        context.update({
+            'fields_per_type': json.dumps(fields_per_type),
+        })
+        return context
+
+    def get_object(self, queryset=None):
+        try:
+            self.page = Page.objects.get(slug=self.kwargs['slug'])
+        except Page.DoesNotExist:
+            raise Http404()
+        return self.get_section()
+
+    def get_section(self):
+        try:
+            section = self.page.sections.get(number=self.kwargs['number'])
+        except Section.DoesNotExist:
+            raise Http404()
+        return section
+
+    def get(self, request, *args, **kwargs):
+        self.object = self.get_object()
+        return self.render_to_response(self.get_context_data())
+
+    def post(self, request, *args, **kwargs):
+        self.object = self.get_object()
+        form = self.get_form()
+
+        if form.is_valid():
+            section = form.save()
+            if section:
+                return HttpResponseRedirect(section.page.get_absolute_url())
+            elif self.page.sections.exists():
+                return HttpResponseRedirect(self.page.get_absolute_url())
+            else:
+                return HttpResponseRedirect('/')
+        return self.render_to_response(self.get_context_data(form=form))
+
+class CreateSection(EditSection):
+    def get_section(self):
+        return Section(page=self.page)
+
+class UpdateSection(EditSection):
+    pass