Custom templates in python
Question
I am trying to implement custom template formatting in python accomplishing two things
Django like delimiter
{{ placeholder }}
eg.
from string import Template
class MyTemplate(Template):
delimiter="{{..}}" #it is only for clarification purpose, though it is invalid
mt = MyTemplate("HELLO {{ world }}")
mt.substitute(world="WORLD")
If there is key error or value error, skip that identifier.
class MyTemplate(Template): delimiter="{{..}}" #it is only for clarification purpose
data = "HELLO {{ world }}, this is 1st program {{ program }}"
mt = MyTemplate(data)
mt.substitute(world="WORLD")
then o/p should be,
HELLO WORLD, this is 1st program
As per my knowledge, we can use templates engines like jinja2 but that is my last option. I am preferring to do it using python native libraries.
Though if you want to suggest any template engine (if possible with example), then it will be also good.
Thanks in advance.
1 answers
solution1
1 2014-06-12 12:43:43
If all you want is to just do simple string formatting, python includes the str.format() method as well as Template Strings .
Straight from the docs
>>> from string import Template
>>> s = Template('$who likes $what')
>>> s.substitute(who='tim', what='kung pao')
'tim likes kung pao'
>>> d = dict(who='tim')
>>> Template('Give $who $100').substitute(d)
Traceback (most recent call last):
...
ValueError: Invalid placeholder in string: line 1, col 11
>>> Template('$who likes $what').substitute(d)
Traceback (most recent call last):
...
KeyError: 'what'
>>> Template('$who likes $what').safe_substitute(d)
'tim likes $what'
If you need to introduce any sort of logic into the templates, then I would be so bold as to say it will be way over your head to write yourself properly and you'll want to use a library. Jinja2 is an excellent template library for general purpose use. If you've ever used Django's templating system, it will be a breeze to use as Jinja2 is based on Django.
Some code I've used with Jinja2
import jinja2
jinja2.env = jinja2.Environment(
loader=jinja2.PackageLoader(package_name=__name__,
package_path='templates'),
trim_blocks=True,
extensions=[
'jinja2.ext.with_', # add the with tag
],
)
context = {
'results': results,
'javascript': js,
'css': css,
'version': '.'.join(str(n) for n in __version__),
}
template = env.get_template('my_template.html')
rendered_template = template.render(context)
In my_template.html
<html>
<head>
<title>Hello World</title>
<style>{{ css }}</style>
<script>{{ javascript }}</script>
</head>
<body>
<h1>Hello world</h1>
<ul>
{% for result in results %}
<div>
{{ result.winner_name }}<br />
{{ result.get_score() }}
</div>
{% endfor %}
</ul>
</body>
</html>
One difference between Django templating and Jinja2 templating is that Jinja2's philosophy wasn't about making it easy for designers to use; so, function calls are allowed within templates.
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