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# Why Jinja?

Jinja provides yet another template rendering solution for TurboGears, but it has a couple of advantages for specific situations:

> - It is super fast,

> - It’s syntax was inspired by django-templates and dojo’s DTL so if you are migrating from Django it’s the natural choice.

> - It lacks some of the most hated (anti)features of django templates.
>     - you can do template logic
>     - Autoescaping is off by default.

> - It is sandboxable, so it’s possible to let non-trusted users edit the templates.

## TurboGears features missing in Jinja

### Dotted Notation

Currently Jinja does not support dotted notation so if you’re using Jinja you will have to turn it off in app_cfg.py:

    base_config.use_dotted_templatenames = False

This means you’ll write expose statements with path strings:

    @expose('index.html')

The standard start location is assumed to be your templates directiory, so if you have admin page templates under an admin directory inside templates you’d do:

    @expose('/admin/index.html')

### Jinja1

The current TG renderer is for jinja2 and will not work with jinja1, jinja1 is deprecated and the author wants everyone to move to jinja2 :)

## Using Jinja in TG2

TurboGears allows you to setup and use jinja templates by simply adding it to the list of renderers to prepare in base_config:

    base_config.renderers.append('jinja')

You can also set it as the default renderer by setting:

    base_config.default_renderer = "jinja"

The Jinja docs cover template syntax very well, so we’ll not repeat it here. Instead, we refer you to their site.

### Extensions

Jinja2 supports loading extensions to add new tags, this is supported on TG2 by adding the import name to the extension list in base_config:

    base_config.jinja_extensions = ['jinja2.ext.i18n', 'jinja2.ext.loopcontrols']

The setting jinja_extensions is a list of strings, each string is the import name of one extension, in this example ‘jinja2.ext.i18n’ is a module in our python installation (which comes with jinja2).

More on jinja extensions on the Jinja extension section from the jinja documents.

### Filters

Jinja2 supports loading functions to add new filters, this is supported on TG2 by adding the function directly to the filter dictionary in base_config, where they key is the name the template will use to lookup the filter:

    base_config.jinja_filters = {'my_filter': my_filter, 'other_filter_function': other_filter_function}

As you can see here we are using the functions directly, you can also have jinja2 autoload your filters by creating a file called jinja_filters.py inside the folder templatetools on you lib filter of you application. If you use the jinja_filters.py file, try to keep module namespace pollution to a minimum, a good alternative is to use the __all__ variable to hide all functions and imports and only expose the filter functions to the auto importer mechanism.

More on jinja filters on the Jinja custom filter section from the jinja documents.