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Jinja Custom extension for moving block content into the footer
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| 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) |
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| <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> |
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