hyperking/jinja_test.py

## jinja_test.py
from flask import Flask,render_template, render_template_string
from pprint import pprint
'''HTML JINJA TEMPLATE'''
# create a new test.html file with the jinjaTemplateString below to view the issue.
jinjaTemplateString = '''
    <html> <head></head> <body> <h1>Test template</h1>
    {% push 'js' %} ABC {% endpush %}

    {% push 'js' %} XYZ {% endpush %}

    {% push 'js' %} 123 {% endpush %}
    {{ pull }}<br>
    </body> </html>
    '''

'''custom jinja2 extension'''
from jinja2 import Markup, nodes
from jinja2.ext import Extension
from jinja2.nodes import ContextReference

class JavascriptBuilderExtension(Extension):
    tags = set(['push','pull'])

    def __init__(self, environment):
        super(JavascriptBuilderExtension, self).__init__(environment)
        self._myScope = {}
        self.callstring = ""

    def parse(self, parser):
        """Parse tokens """
        tag = parser.stream.__next__()
        ctx_ref = ContextReference()

        if tag.value == "push":
            args = [ctx_ref, parser.parse_expression(), nodes.Const(tag.lineno)]
            body = parser.parse_statements(['name:endpush'], drop_needle=True)
            callback = self.call_method('compiled', args)
        else:
            body = []
            self.callstring = parser.parse_expression().value
            callback = self.call_method('scope', [ctx_ref])

        return nodes.CallBlock(callback, [], [], body).set_lineno(tag.lineno)

    def scope(self, context, caller):
        if self.callstring:
            return str(context.vars["_myScope"].get(self.callstring) )
        return str(context.vars["_myScope"])

    def compiled(self, context, tagname, linenum, caller):
        tagname = "{}".format(tagname, linenum)
        if "_myScope" not in context.vars:
            context.vars["_myScope"] = {}
        if not context.vars["_myScope"].get(tagname):
            context.vars["_myScope"][tagname] = ""
        context.vars["_myScope"][tagname] += caller()
        return "<!-- moved {} from line {} -->".format(tagname, linenum)


'''initialize Flask app'''
app = Flask(__name__)
app.config['TEMPLATES_AUTO_RELOAD'] = True

'''include custom extension to flask app'''
app.jinja_env.add_extension(JavascriptBuilderExtension)

@app.route("/")
def hello():
    ''' using render template string appears to work as intended'''
    # return render_template_string(jinjaTemplateString, pull=pushedcontent)
    # ''' using render template renders duplicate content'''
    return render_template('test.html')

if __name__ == "__main__":
    app.run(debug=True)

## test.html
<html> <head></head> <body> <h1>Test template</h1>
{% push 'js' %} 123{% endpush %}
{% push 'js' %}xyz {% endpush %}
<h2>pull ouput bellow</h2>
{% pull 'js' %}

</body> </html>
	from flask import Flask,render_template, render_template_string
	from pprint import pprint
	'''HTML JINJA TEMPLATE'''
	# create a new test.html file with the jinjaTemplateString below to view the issue.
	jinjaTemplateString = '''
	<html> <head></head> <body> <h1>Test template</h1>
	{% push 'js' %} ABC {% endpush %}

	{% push 'js' %} XYZ {% endpush %}

	{% push 'js' %} 123 {% endpush %}
	{{ pull }}<br>
	</body> </html>
	'''

	'''custom jinja2 extension'''
	from jinja2 import Markup, nodes
	from jinja2.ext import Extension
	from jinja2.nodes import ContextReference

	class JavascriptBuilderExtension(Extension):
	tags = set(['push','pull'])

	def __init__(self, environment):
	super(JavascriptBuilderExtension, self).__init__(environment)
	self._myScope = {}
	self.callstring = ""

	def parse(self, parser):
	"""Parse tokens """
	tag = parser.stream.__next__()
	ctx_ref = ContextReference()

	if tag.value == "push":
	args = [ctx_ref, parser.parse_expression(), nodes.Const(tag.lineno)]
	body = parser.parse_statements(['name:endpush'], drop_needle=True)
	callback = self.call_method('compiled', args)
	else:
	body = []
	self.callstring = parser.parse_expression().value
	callback = self.call_method('scope', [ctx_ref])

	return nodes.CallBlock(callback, [], [], body).set_lineno(tag.lineno)

	def scope(self, context, caller):
	if self.callstring:
	return str(context.vars["_myScope"].get(self.callstring) )
	return str(context.vars["_myScope"])

	def compiled(self, context, tagname, linenum, caller):
	tagname = "{}".format(tagname, linenum)
	if "_myScope" not in context.vars:
	context.vars["_myScope"] = {}
	if not context.vars["_myScope"].get(tagname):
	context.vars["_myScope"][tagname] = ""
	context.vars["_myScope"][tagname] += caller()
	return "<!-- moved {} from line {} -->".format(tagname, linenum)


	'''initialize Flask app'''
	app = Flask(__name__)
	app.config['TEMPLATES_AUTO_RELOAD'] = True

	'''include custom extension to flask app'''
	app.jinja_env.add_extension(JavascriptBuilderExtension)

	@app.route("/")
	def hello():
	''' using render template string appears to work as intended'''
	# return render_template_string(jinjaTemplateString, pull=pushedcontent)
	# ''' using render template renders duplicate content'''
	return render_template('test.html')

	if __name__ == "__main__":
	app.run(debug=True)
	<html> <head></head> <body> <h1>Test template</h1>
	{% push 'js' %} 123{% endpush %}
	{% push 'js' %}xyz {% endpush %}
	<h2>pull ouput bellow</h2>
	{% pull 'js' %}

	</body> </html>