` element in the `site_header.html` file and only close it in `site_footer.html` file.
Besides, as in any other Trac Jinja2 template, you can use some Trac specific features, for example the `${href.chrome('site/style.css')}` attribute references `style.css` in the environment's `htdocs/` directory. In a similar fashion `${chrome.htdocs_location}` is used to specify the common `htdocs/` directory belonging to a Trac installation. That latter location can however be overridden using the [TracIni#trac-htdocs_location-option "[trac] htdocs_location"] setting.
Example snippet of adding introduction text to the new ticket form (but not shown during preview):
- first we need to introduce the extra "content" of this notice, if it's appropriate for the request. For that, we add this snippet in the `site_footer.html` placeholder file:
{{{#!xml
# if req.path_info == '/newticket' and 'preview' not in req.args:
Please make sure to search for existing tickets before reporting a new one!
# endif
}}}
- second, we need to dynamically alter the rest of the content in order to position that notice at the desired location. For that, we add this snippet to the `site_head.html` placeholder file:
{{{#!xml
}}}
This example illustrates a technique of using `req.path_info` to limit scope of changes to one view only. For instance, to make changes only for timeline and avoid modifying other sections, use `req.path_info == '/timeline'` as the condition in a `# if` test.
More examples snippets for placeholder files can be found at [trac:wiki:CookBook/SiteHtml CookBook/SiteHtml].
Example snippets for `style.css` can be found at [trac:wiki:CookBook/SiteStyleCss CookBook/SiteStyleCss].
=== Sharing Templates in Multiple Environments
The `site_*.html` templates, despite their name, can be put in a shared templates directory, see the [[TracIni#inherit-templates_dir-option|[inherit] templates_dir]] option. This could provide easier maintenance, as global `site_head.html`, `site_header.html` and `site_footer.html` files can be made to `# include` any other local existing header, footer and newticket snippets.
== Project List #ProjectList
You can use a custom Genshi template to display the list of projects if you are using Trac with multiple projects.
The following is the basic template used by Trac to display a list of links to the projects. For projects that could not be loaded, it displays an error message. You can use this as a starting point for your own index template:
FIXME
{{{#!text/html
Available Projects
Available Projects
}}}
Once you've created your custom template you will need to configure the webserver to tell Trac where the template is located:
For [wiki:TracModWSGI mod_wsgi]:
{{{#!python
os.environ['TRAC_ENV_INDEX_TEMPLATE'] = '/path/to/template.html'
}}}
For [TracFastCgi FastCGI]:
{{{#!apache
FastCgiConfig -initial-env TRAC_ENV_PARENT_DIR=/parent/dir/of/projects \
-initial-env TRAC_ENV_INDEX_TEMPLATE=/path/to/template
}}}
For [TracModPython mod_python]:
{{{#!apache
PythonOption TracEnvParentDir /parent/dir/of/projects
PythonOption TracEnvIndexTemplate /path/to/template
}}}
For [TracCgi CGI]:
{{{#!apache
SetEnv TRAC_ENV_INDEX_TEMPLATE /path/to/template
}}}
For TracStandalone, you'll need to set up the `TRAC_ENV_INDEX_TEMPLATE` environment variable in the shell used to launch tracd:
- Unix:
{{{#!sh
$ export TRAC_ENV_INDEX_TEMPLATE=/path/to/template
}}}
- Windows:
{{{#!sh
$ set TRAC_ENV_INDEX_TEMPLATE=/path/to/template
}}}
== Project Templates
The appearance of each individual Trac environment, ie instance of a project, can be customized independently of other projects, even those hosted on the same server. The recommended way is to use `site_{head,header,footer}.html` templates whenever possible, see [#SiteAppearance]. Using `site_{head,header,footer}.html` means changes are made to the original templates as they are rendered, and you should not normally need to redo modifications whenever Trac is upgraded. If you do make a copy of `theme.html` or any other Trac template, you need to migrate your modifications to the newer version. If not, new Trac features or bug fixes may not work as expected.
With that word of caution, any Trac template may be copied and customized. The default Trac templates are located in the Trac egg or wheel, such as `/usr/lib/pythonVERSION/site-packages/Trac-VERSION.egg/trac/templates, ../trac/ticket/templates, ../trac/wiki/templates`. The [#ProjectList] template file is called `index.html`, while the template responsible for main layout is called `theme.html`. Page assets such as images and CSS style sheets are located in the egg's or wheel's `trac/htdocs` directory.
However, do not edit templates or site resources inside the Trac egg/wheel. Reinstalling Trac overwrites your modifications. Instead use one of these alternatives:
* For a modification to one project only, copy the template to project `templates` directory.
* For a modification shared by several projects, copy the template to a shared location and have each project point to this location using the [[TracIni#inherit-templates_dir-option|[inherit] templates_dir]] option.
Trac resolves requests for a template by first looking inside the project, then in any inherited templates location, and finally inside the Trac egg or wheel.
Trac caches templates in memory by default to improve performance. To apply a template you need to restart the web server.
----
See also TracIni, TracNavigation