The TG2 quickstart command produces this basic TG site. Here's how it works.
When you want a model for storing favorite links or wiki content, the /model folder in your site is ready to go.
You can build a dynamic site without any data model at all. There still be a default data-model template for you if you didn't enable authentication and authorization in quickstart. If you have enabled authorization, the auth data-model is ready-made.
The "root.py" file under the /controllers folder has your URLs. When you called this url (about), the command went through the RootController class to the about() method.
Those Python methods are responsible to create the dictionary of variables that will be used in your web views (template).
A web page viewed by user could be constructed by single or several reusable templates under /templates. Take 'about' page for example, each reusable templates generating a part of the page. We'll cover them in the order of where they are found, listed near the top of the about.html template
header.html - The "header.html" template contains the HTML code to display the 'header': The div, the h1 tag, and the subtitle are there, and the the blue gradient, TG2 logo, are placed by way of the .css file (from style.css) are all at the top of every page it is included on. When the "about.html" template is called, it includes this "header.html" template (and the others) with a <xi:include /> tag, part of the Genshi templating system. The "header.html" template is not a completely static HTML -- it also includes (via <xi:include/> tag) "master.html", which dynamically displays the current page name with a Genshi template method called "replace" with the code: <span py:replace="page"/>. It means replace this <span /> region with the contents found in the variable 'page' that has been sent in the dictionary to this "about.html" template, and is available through that namespace for use by this "header.html" template. That's how it changes in the header depending on what page you are visiting.
sidebars.html - The
sidebars (navigation areas on the right side of the page) are
generated as two separate py:def blocks
in the "sidebars.html" template. The py:def
construct is best thought of as a "macro" code... a simple way to
separate and reuse common code snippets. All it takes to include
these on the "about.html" page template is to write
$${sidebar_top()}
$${sidebar_bottom()}
in the page where they are wanted. CSS styling (in
"/public/css/style.css") floats them off to the right side. You can
remove a sidebar or add more of them, and the CSS will place them one
atop the other.
This is, of course, also exactly how the header and footer templates are also displayed in their proper places, but we'll cover that in the "master.html" template below.
Oh, and in sidebar_top we've added a dynamic menu that shows the link to this page at the top when you're at the "index" page, and shows a link to the Home (index) page when you're here. Study the "sidebars.html" template to see how we used py:choose for that.
footer.html - The "footer.html" block is simple, but also utilizes a special "replace" method to set the current YEAR in the footer copyright message. The code is: <span py:replace="now.strftime('%Y')"> and it uses the variable "now" that was passed in with the dictionary of variables. But because "now" is a datetime object, we can use the Python "strftime()" method with the "replace" call to say "Just Display The Year Here". Simple, elegant; we format the date display in the template (the View in the Model/View/Controller architecture) rather than formatting it in the Controller method and sending it to the template as a string variable.
master.html - The "master.html" template is called last, by design. The "master.html" template controls the overall design of the page we're looking at, calling first the "header" py:def macro, then the putting everything from this "about.html" template into the "main_content" div, and then calling the "footer" macro at the end. Thus the "master.html" template provides the overall architecture for each page in this site.
But why then shouldn't we call it first? Isn't it the most important? Perhaps, but that's precisely why we call it LAST. The "master.html" template needs to know where to find everything else, everything that it will use in py:def macros to build the page. So that means we call the other templates first, and then call "master.html".
There's more to the "master.html" template... study it to see how the <title> tags and static JS and CSS files are brought into the page. Templating with Genshi is a powerful tool and we've only scratched the surface. There are also a few little CSS tricks hidden in these pages, like the use of a "clearingdiv" to make sure that your footer stays below the sidebars and always looks right. That's not TG2 at work, just CSS. You'll need all your skills to build a fine web app, but TG2 will make the hard parts easier so that you can concentrate more on good design and content rather than struggling with mechanics.
Good luck with TurboGears 2!