Django snippets

import copy

from django import template
from django import forms
from django.utils.datastructures import SortedDict

register = template.Library()

def get_fieldset(parser, token):
    try:
        name, fields, as_, variable_name, from_, form = token.split_contents()
    except ValueError:
        raise template.TemplateSyntaxError('bad arguments for %r'  % token.split_contents()[0])

    return FieldSetNode(fields.split(','), variable_name, form)

get_fieldset = register.tag(get_fieldset)


class FieldSetNode(template.Node):
    def __init__(self, fields, variable_name, form_variable):
        self.fields = fields
        self.variable_name = variable_name
        self.form_variable = form_variable

    def render(self, context):
        
        form = template.Variable(self.form_variable).resolve(context)
        new_form = copy.copy(form)        
        new_form.fields = SortedDict([(key, value) for key, value in form.fields.items() if key in self.fields])

        context[self.variable_name] = new_form

        return u''