Created
August 26, 2013 21:56
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A Django Template tag used to construct urls with current querystring parameters. This is based on some code that I've written some years ago. Enjoy.
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from django import template | |
from django.http import QueryDict | |
from django.utils.safestring import mark_safe | |
from django.template.loader import get_template | |
register = template.Library() | |
class QueryStringNode(template.Node): | |
def __init__(self, to_add, to_remove): | |
self.to_add = to_add | |
self.to_remove = to_remove | |
def render(self, context): | |
if 'request' not in context: | |
raise template.TemplateSyntaxError( | |
"'django.core.context_processors.request' not in TEMPLATE_CONTEXT_PROCESSORS" | |
) | |
querydict = context['request'].GET.copy() | |
return self.get_querystring(querydict, self.to_add, self.to_remove, context) | |
def parse_to_remove(self, to_remove): | |
if not to_remove: | |
return [] | |
return [r.strip() for r in to_remove.strip('"').split(',')] | |
def parse_to_add(self, to_add): | |
kw = {} | |
to_add = to_add.strip('"') | |
if to_add == '': | |
return kw | |
for a in to_add.split(','): | |
k, v = a.strip().split('=') | |
kw[k] = v | |
return kw | |
def get_querystring(self, querydict, to_add, to_remove, context): | |
new_querydict = QueryDict(querydict.urlencode(), mutable=True) | |
try: | |
to_add = self.parse_to_add(to_add) | |
to_remove = self.parse_to_remove(to_remove) | |
except ValueError: | |
raise | |
raise template.TemplateSyntaxError("Unable to parse arguments") | |
for r in to_remove: | |
try: | |
del new_querydict[r] | |
except KeyError: | |
pass | |
for k, v in to_add.items(): | |
if v.startswith('ctx:'): | |
v = v.replace('ctx:', '') | |
try: | |
value = template.Variable(v).resolve(context) | |
except template.VariableDoesNotExist: | |
value = None | |
if value: | |
new_querydict[k] = value | |
else: | |
new_querydict[k] = v | |
return new_querydict.urlencode() | |
@register.tag | |
def get_querystring(parser, token): | |
""" | |
First argument contains a list of variables that will be added to querystring. | |
If value starts with "ctx:", the value will be taken from template context:: | |
{% get_querystring "pk=ctx:object.pk,a=1" %} | |
Second (optional) argument contains a list of variables that will be removed | |
from the querystring:: | |
{% get_querystring "pk=ctx:object.pk,a=1" "b,c" %} | |
""" | |
bits = token.split_contents() | |
if len(bits) < 2: | |
raise template.TemplateSyntaxError("%s takes at least one argument" % bits[0]) | |
to_add = bits[1] | |
try: | |
to_remove = bits[2] | |
except IndexError: | |
to_remove = None | |
return QueryStringNode(to_add, to_remove) |
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