Mezzanine comes with the ability to use different sets of templates depending on the device being used to access the website. For example one set of templates may be used for desktop browsers with a corresponding set of templates being used for mobile phones.
Devices are grouped into types with each type being named after the sub-directory containing its specific set of templates. Each device is then defined by a list of strings that could be found in the user agent that matches the particular device. This mapping of device sub-directory names to user agent strings is defined in the setting DEVICE_USER_AGENTS:
DEVICE_USER_AGENTS = ( ("mobile", ("Android", "BlackBerry", "iPhone")), ("desktop", ("Windows", "Macintosh", "Linux")), )
Given the above example value for DEVICE_USER_AGENTS suppose a view or template referenced the template blog/index.html. If an iPhone made the request to the website, the template mobile/blog/index.html would be searched for, and if a Windows OS made the request then the template desktop/blog/index.html would be searched for.
If the device specific templates don’t exist or a user agent isn’t matched to any of the device specific strings, then the original template name (blog/index.html in the above example) will be used as per usual with Django. This means that supporting device specific templates is entirely optional.
You can also specify which device should be treated as the default by defining the setting DEVICE_DEFAULT. For example to ensure templates for the mobile device group are used even when no matching user agent is found, simply define the following in your project’s settings module:
DEVICE_DEFAULT = "mobile"
Mezzanine includes the app mezzanine.mobile which contains a full set of default templates and assets for creating a mobile version of your site. Simply add mezzanine.mobile to your INSTALLED_APPS setting to use it.
Using the DEVICE_USER_AGENTS setting, Mezzanine simply prefixes any referenced template path with the device specific sub-directory name if a user agent matches one of the strings specified for the device. For example if a user agent matches the mobile device set of templates, a reference to blog/index.html will be changed to the list ["mobile/blog/index.html", "blog/index.html"] under the hood.
To achieve this, the middleware mezzanine.core.middleware.TemplateForDeviceMiddleware catches Django TemplateResponse responses, and changes the template list prior to the response being rendered. As such, any views you implement should return TemplateResponse objects. The table below lists Mezzanine versions of Django features that can be used to ensure a TemplateResponse is returned.