django-layers-hr 1.10.0.0

Installation

1. Install or add django-layers-hr to your Python path.

2. Add layers after django.contrib.static to your INSTALLED_APPS setting.

3. Ensure the app that you will be creating layers for appears first in INSTALLED_APPS else template override won’t work.

Example

Note: there is a working example in the example subdirectory.

We have sites example.com, basic.example.com and smart.example.com. Each of the sites have their own settings.py, thus different Django processes.

templates
    - basic
        - foo.html (1)
        - bar.html (2)
    - smart
        - bar.html (3)
    - web
        - bar.html (4)

static
    - basic
        - foo.css (5)
        - bar.css (6)
    - smart
        - bar.css (7)
    - web
        - bar.css (8)

LAYERS = {'tree': ['basic', ['smart'], ['web']]}

LAYERS = {'tree': ['basic', ['smart', ['web']]]}

LAYERS = {'tree': ['basic', ['smart'], ['web']], 'current': 'web'}

INSTALLED_APPS = (
    'myapp',
    'layers',
    ...
)

TEMPLATE_LOADERS = (
    'layers.loaders.filesystem.Loader',
    'django.template.loaders.filesystem.Loader',
    'layers.loaders.app_directories.Loader',
    'django.template.loaders.app_directories.Loader',
)

STATICFILES_FINDERS = (
    'layers.finders.FileSystemFinder',
    'django.contrib.staticfiles.finders.FileSystemFinder',
    'layers.finders.AppDirectoriesFinder',
    'django.contrib.staticfiles.finders.AppDirectoriesFinder',
)

Overriding templates from other apps

The normal template resolution rules apply. Creating eg. templates/web/registration/login.html will override the login page for web only.

Collectstatic

Collectstatic remains unaffected. The collector delegates to finders, so all layer aware resources end up with partial paths under the STATIC_ROOT directory.

Decorators

A user could follow a link that leads him to a layer that serves a broken page. For example a web site is served on www.site.com with an accompanying basic site m.site.com. Visiting www.site.com/flashy-dashboard with a basic device like a Samsung E250 will result in the user being redirected to m.site.com/flashy-dashboard. That page probably does not exist for basic devices because it can’t render it well enough. In such a case a decorator exclude_from_layers is provided that renders a friendly page instead of a 404 or 500 error:

class WebOnlyView(TemplateView):
    template_name = "layers/web_only_view.html"

    @exclude_from_layers(layers=("basic",))
    def get(self, *args, **kwargs):
        return super(WebOnlyView, self).get(*args, **kwargs)

Request based layer lookup

The preferred way of layer lookup is through the presense of an X-Django-Layer header in the request. Django Layers layer lookup is very similar to the site object lookup done in django.contrib.sites. If a layer is explicitly defined in settings then that is used, else the request headers are inspected.

During development you will likely define the layer in your settings file, but in a production environment you don’t want a Django process per layer, so request based lookups are preferred.

Layer objects

The management command load_layers creates a Layer object for each layer in your project. It is useful for doing layer based filtering at database level.

Can I add my own layers?

Yes! Basic, smart and web are just exmaples. You can define any hierarchy with any names.

Authors

• Hedley Roos

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