Integrating 3rd party apps into your site

With FeinCMS come a set of standard views which you might want to check out before starting to write your own. Included is a standard view for pages, and a set of generic view drop-in replacements which know about the CMS.

Default page handler

The default CMS handler view is feincms.views.cbv.handler. You can add the following as last line in your urls.py to make a catch-all for any pages which were not matched before:

from feincms.views.cbv.views import Handler
handler = Handler.as_view()

urlpatterns += patterns('',
    url(r'^$', handler, name='feincms_home'),
    url(r'^(.*)/$', handler, name='feincms_handler'),
)

Note that this default handler can also take a keyword parameter path to specify which url to render. You can use that functionality to implement a default page by adding another entry to your urls.py:

from feincms.views.cbv.views import Handler
handler = Handler.as_view()

...
    url(r'^$', handler, {'path': '/rootpage'},
        name='feincms_home')
...

Please note that it’s easier to include feincms.urls at the bottom of your own URL patterns like this:

# ...

urlpatterns += patterns('',
    url(r'', include('feincms.urls')),
)

The URLconf entry names feincms_home and feincms_handler must both exist somewhere in your project. The standard feincms.urls contains definitions for both. If you want to provide your own view, it’s your responsability to create correct URLconf entries.

Generic and custom views

If you use FeinCMS to manage your site, chances are that you still want to use generic and/or custom views for certain parts. You probably still need a feincms_page object inside your template to generate the navigation and render regions not managed by the generic views. The best way to ensure the presence of a feincms_page instance in the template context is to add feincms.context_processors.add_page_if_missing to your TEMPLATE_CONTEXT_PROCESSORS setting.

Integrating 3rd party apps

Third party apps such as django-registration can be integrated in the CMS too. ApplicationContent lets you delegate a subset of your page tree to a third party application. The only thing you need is specifying a URLconf file which is used to determine which pages exist below the integration point.

Adapting the 3rd party application for FeinCMS

The integration mechanism is very flexible. It allows the website administrator to add the application in multiple places or move the integration point around at will. Obviously, this flexibility puts several constraints on the application developer. It is therefore probable, that you cannot just drop in a 3rd party application and expect it to work. Modifications of urls.py and the templates will be required.

The following examples all assume that we want to integrate a news application into FeinCMS. The ApplicationContent will be added to the page at /news/, but that’s not too important really, because the 3rd party app’s assumption about where it will be integrated can be too easily violated.

An example urls.py follows:

from django.conf.urls import patterns, include, url
from django.views.generic.detail import DetailView
from django.views.generic.list import ListView
from news.models import Entry


urlpatterns = patterns('',
    url(r'^$', ListView.as_view(
        queryset=Entry.objects.all(),
        ), name='entry_list'),
    url(r'^(?P<slug>[^/]+)/$', DetailView.as_view(
        queryset=Entry.objects.all(),
        ), name='entry_detail'),
)

Please note that you should not add the news/ prefix here. You should not reference this urls.py file anywhere in a include statement.

Registering the 3rd party application with FeinCMS’ ApplicationContent

It’s as simple as that:

from feincms.content.application.models import ApplicationContent
from feincms.module.page.models import Page

Page.create_content_type(ApplicationContent, APPLICATIONS=(
    ('news.urls', 'News application'),
    ))

Writing the models

Because the URLconf entries entry_list and entry_detail aren’t reachable through standard means (remember, they aren’t included anywhere) it’s not possible to use standard reverse calls to determine the absolute URL of a news entry. FeinCMS provides its own app_reverse function (see More on reversing URLs for details) and permalink decorator mimicking the interface of Django’s standard functionality:

from django.db import models
from feincms.content.application import models as app_models

class Entry(models.Model):
   title = models.CharField(max_length=200)
   slug = models.SlugField()
   description = models.TextField(blank=True)

   class Meta:
       ordering = ['-id']

   def __unicode__(self):
       return self.title

   @app_models.permalink
   def get_absolute_url(self):
       return ('entry_detail', 'news.urls', (), {
           'slug': self.slug,
           })

The only difference is that you do not only have to specify the view name (entry_detail) but also the URLconf file (news.urls) for this specific permalink decorator. The URLconf string must correspond to the specification used in the APPLICATIONS list in the create_content_type call.

Note

Previous FeinCMS versions only provided a monkey patched reverse method with a slightly different syntax for reversing URLs. This behavior is still available and as of now (FeinCMS 1.5) still active by default. It is recommended to start using the new way right now and add FEINCMS_REVERSE_MONKEY_PATCH = False to your settings file.

Returning content from views

Three different types of return values can be handled by the application content code:

Unicode data is inserted verbatim into the output. HttpResponse instances are returned directly to the client under the following circumstances:

  • The HTTP status code differs from 200 OK (Please note that 404 errors may be ignored if more than one content type with a process method exists on the current CMS page.)
  • The resource was requested by XmlHttpRequest (that is, request.is_ajax returns True)
  • The response was explicitly marked as standalone by the feincms.views.decorators.standalone() view decorator
  • The mimetype of the response was not text/plain or text/html

Otherwise, the content of the response is unpacked and inserted into the CMS output as unicode data as if the view returned the content directly, not wrapped into a HttpResponse instance.

If you want to customize this behavior, provide your own subclass of ApplicationContent with an overridden send_directly method. The described behavior is only a sane default and might not fit everyone’s use case.

Note

The string or response returned should not contain <html> or <body> tags because this would invalidate the HTML code returned by FeinCMS.

Letting the application content use the full power of Django’s template inheritance

If returning a simple unicode string is not enough and you’d like to modify different blocks in the base template, you have to ensure two things:

  • Use the class-based page handler. This is already the default if you include feincms.urls or feincms.views.cbv.urls.
  • Make sure your application views use the third return value type described above: A tuple consisting of a template and a context dict.

The news application views would then look as follows. Please note the absence of any template rendering calls:

views.py:

from django.shortcuts import get_object_or_404
from news.models import Entry

def entry_list(request):
    # Pagination should probably be added here
    return 'news/entry_list.html', {'object_list': Entry.objects.all()}

def entry_detail(request, slug):
    return 'news/entry_detail', {'object': get_object_or_404(Entry, slug=slug)}

urls.py:

from django.conf.urls.defaults import patterns, include, url

urlpatterns = patterns('news.views',
    url(r'^$', 'entry_list', name='entry_list'),
    url(r'^(?P<slug>[^/]+)/$', 'entry_detail', name='entry_detail'),
)

The two templates referenced, news/entry_list.html and news/entry_detail.html, should now extend a base template. The recommended notation is as follows:

{% extends feincms_page.template.path|default:"base.html" %}

{% block ... %}
{# more content snipped #}

This ensures that the the selected CMS template is still used when rendering content.

Note

Older versions of FeinCMS only offered fragments for a similar purpose. They are still suported, but it’s recommended you switch over to this style instead.

Warning

If you add two application content blocks on the same page and both use this mechanism, the later ‘wins’.

More on reversing URLs

Application content-aware URL reversing is available both for Python and Django template code.

The function works almost like Django’s own reverse() method except that it resolves URLs from application contents. The second argument, urlconf, has to correspond to the URLconf parameter passed in the APPLICATIONS list to Page.create_content_type:

from feincms.content.application.models import app_reverse
app_reverse('mymodel-detail', 'myapp.urls', args=...)

or:

app_reverse('mymodel-detail', 'myapp.urls', kwargs=...)

The template tag has to be loaded from the applicationcontent_tags template tag library first:

{% load applicationcontent_tags %}
{% app_reverse "mymodel_detail" "myapp.urls" arg1 arg2 %}

or:

{% load applicationcontent_tags %}
{% app_reverse "mymodel_detail" "myapp.urls" name1=value1 name2=value2 %}

Storing the URL in a context variable is supported too:

{% load applicationcontent_tags %}
{% app_reverse "mymodel_detail" "myapp.urls" arg1 arg2 as url %}

Additional customization possibilities

The ApplicationContent offers additional customization possibilites for those who need them. All of these must be specified in the APPLICATIONS argument to create_content_type.

  • urls: Making it easier to swap the URLconf file:

    You might want to use logical names instead of URLconf paths when you create your content types, so that the ApplicationContent apps aren’t tied to a particular urls.py file. This is useful if you want to override a few URLs from a 3rd party application, f.e. replace registration.urls with yourapp.registration_urls:

    Page.create_content_type(ApplicationContent, APPLICATIONS=(
      ('registration', 'Account creation and management', {
          'urls': 'yourapp.registration_urls',
          }),
      )
  • admin_fields: Adding more fields to the application content interface:

    Some application contents might require additional configuration parameters which should be modifyable by the website administrator. admin_fields to the rescue!

    def registration_admin_fields(form, *args, **kwargs):
      return {
          'exclusive_subpages': forms.BooleanField(
              label=_('Exclusive subpages'),
              required=False,
              initial=form.instance.parameters.get('exclusive_subpages', True),
              help_text=_('Exclude everything other than the application\'s content when rendering subpages.'),
              ),
          }
    
    Page.create_content_type(ApplicationContent, APPLICATIONS=(
      ('registration', 'Account creation and management', {
          'urls': 'yourapp.registration_urls',
          'admin_fields': registration_admin_fields,
          }),
      )

    The form fields will only be visible after saving the ApplicationContent for the first time. They are stored inside a JSON-encoded field. The values are added to the template context indirectly when rendering the main template by adding them to request._feincms_extra_context.

  • path_mapper: Customize URL processing by altering the perceived path of the page:

    The applicaton content uses the remainder of the URL to resolve the view inside the 3rd party application by default. This works fine most of the time, sometimes you want to alter the perceived path without modifying the URLconf file itself.

    If provided, the path_mapper receives the three arguments, request.path, the URL of the current page and all application parameters, and must return a tuple consisting of the path to resolve inside the application content and the path the current page is supposed to have.

    This path_mapper function can be used to do things like rewrite the path so you can pretend that an app is anchored deeper than it actually is (e.g. /path/to/page is treated as “/<slug>/” using a parameter value rather than “/” by the embedded app)

  • view_wrapper: Decorate every view inside the application content:

    If the customization possibilites above aren’t sufficient, view_wrapper can be used to decorate each and every view inside the application content with your own function. The function specified with view_wrapper receives an additional parameters besides the view itself and any arguments or keyword arguments the URLconf contains, appcontent_parameters containing the application content configuration.

Letting 3rd party apps define navigation entries

Short answer: You need the feincms.module.page.extensions.navigation extension module. Activate it like this:

Page.register_extensions('feincms.module.page.extensions.navigation')

Please note however, that this call needs to come after all NavigationExtension subclasses have been processed, because otherwise they will not be available for selection in the page administration! (Yes, this is lame and yes, this is going to change as soon as we find a better solution. In the meantime, stick your subclass definition before the register_extensions call.)

Because the use cases for extended navigations are so different, FeinCMS does not go to great lengths trying to cover them all. What it does though is to let you execute code to filter, replace or add navigation entries when generating a list of navigation entries.

If you have a blog and you want to display the blog categories as subnavigation entries, you could do it as follows:

  1. Create a navigation extension for the blog categories
  2. Assign this navigation extension to the CMS page where you want these navigation entries to appear

You don’t need to do anything else as long as you use the built-in feincms_nav template tag – it knows how to handle extended navigations.

from feincms.module.page.extensions.navigation import NavigationExtension, PagePretender

class BlogCategoriesNavigationExtension(NavigationExtension):
    name = _('blog categories')

    def children(self, page, **kwargs):
        for category in Category.objects.all():
            yield PagePretender(
                title=category.name,
                url=category.get_absolute_url(),
                )

class PassthroughExtension(NavigationExtension):
    name = 'passthrough extension'

    def children(self, page, **kwargs):
        for p in page.children.in_navigation():
            yield p

Page.register_extensions('feincms.module.page.extensions.navigation')

Note that the objects returned should at least try to mimic a real page so navigation template tags as siblings_along_path_to and friends continue to work, ie. at least the following attributes should exist:

title     = '(whatever)'
url       = '(whatever)'

# Attributes that MPTT assumes to exist
parent_id = page.id
tree_id   = page.tree_id
level     = page.level+1
lft       = page.lft
rght      = page.rght