lsemel/capture_extension.py

## capture_extension.py
from jinja2 import nodes
from jinja2.ext import Extension

class CaptureExtension(Extension):
    """
    Generic HTML capture, inspired by Rails' capture helper

    In any template, you can capture an area of content and store it in a global
    variable:

    {% contentfor 'name_of_variable' %}
        blah blah blah
    {% endcontentfor %}

    To display the result
    {{ capture.name_of_variable }}

    Multiple contentfor blocks will append additional content to any previously
    captured content.

    The context is global, and works within macros as well, so it's useful for letting macros define
    javascript or <head> tag content that needs to go at a particular position
    on the base template.

    IMPORTANT: Make sure that whater function you use to render Jinja templates clears the 'capture' global each time it runs
    or else you'll get captured content from previous renders

    Inspired by http://stackoverflow.com/questions/4292630/insert-javascript-at-top-of-including-file-in-jinja-2
    and http://api.rubyonrails.org/classes/ActionView/Helpers/CaptureHelper.html
    """
    tags = set(['contentfor'])

    def __init__(self, environment):
        super(CaptureExtension, self).__init__(environment)

    def parse(self, parser):
        """Parse tokens """
        tag = parser.stream.next()
        args = [parser.parse_expression()]
        body = parser.parse_statements(['name:endcontentfor'], drop_needle=True)
        return nodes.CallBlock(self.call_method('_capture', args),[], [], body).set_lineno(tag.lineno)

    def _capture(self, name, caller):
        if 'capture' not in self.environment.globals:
            self.environment.globals['capture'] = {}
        if name not in self.environment.globals['capture']:
            self.environment.globals['capture'][name] = ''
        self.environment.globals['capture'][name] += caller()
        return ""
	from jinja2 import nodes
	from jinja2.ext import Extension

	class CaptureExtension(Extension):
	"""
	Generic HTML capture, inspired by Rails' capture helper

	In any template, you can capture an area of content and store it in a global
	variable:

	{% contentfor 'name_of_variable' %}
	blah blah blah
	{% endcontentfor %}

	To display the result
	{{ capture.name_of_variable }}

	Multiple contentfor blocks will append additional content to any previously
	captured content.

	The context is global, and works within macros as well, so it's useful for letting macros define
	javascript or <head> tag content that needs to go at a particular position
	on the base template.

	IMPORTANT: Make sure that whater function you use to render Jinja templates clears the 'capture' global each time it runs
	or else you'll get captured content from previous renders

	Inspired by http://stackoverflow.com/questions/4292630/insert-javascript-at-top-of-including-file-in-jinja-2
	and http://api.rubyonrails.org/classes/ActionView/Helpers/CaptureHelper.html
	"""
	tags = set(['contentfor'])

	def __init__(self, environment):
	super(CaptureExtension, self).__init__(environment)

	def parse(self, parser):
	"""Parse tokens """
	tag = parser.stream.next()
	args = [parser.parse_expression()]
	body = parser.parse_statements(['name:endcontentfor'], drop_needle=True)
	return nodes.CallBlock(self.call_method('_capture', args),[], [], body).set_lineno(tag.lineno)

	def _capture(self, name, caller):
	if 'capture' not in self.environment.globals:
	self.environment.globals['capture'] = {}
	if name not in self.environment.globals['capture']:
	self.environment.globals['capture'][name] = ''
	self.environment.globals['capture'][name] += caller()
	return ""