Template Syntax
Now that we’ve seen a simple example of templates in action, let’s go into a bit more detail about how they work. Templates in Tornado are simply text files marked up with Python expressions and control sequences. The syntax of Tornado templates is fairly straightforward and simple. Users familiar with Django, Liquid, or similar frameworks will find a lot of similarities, and should find it easy to pick up.
In Simple Example: Poem Maker Pro, we showed how to use the
render method in a web application to
send HTML to the browser. You can try out the templating system outside of
a Tornado application by importing the template module in the Python
interpreter, and printing the output directly.
>>>from tornado.template import Template>>>content = Template("<html><body><h1>{{ header }}</h1></body></html>")>>>print content.generate(header="Welcome!")<html><body><h1>Welcome!</h1></body></html>
Interpolating Expressions
In Example 2-1, we demonstrated the use of double curly braces to interpolate the value of Python variables into a template. It turns out that you can put any Python expression inside double curly braces. Tornado will insert a string containing whatever that expression evaluated to into the output. Here are a few examples of what’s possible:
>>>from tornado.template import Template>>>print Template("{{ 1+1 }}").generate()2 >>>print Template("{{ 'scrambled eggs'[-4:] }}").generate()eggs >>>print Template("{{ ', '.join([str(x*x) for x in range(10)]) ...
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