rangevaluesfilterspec.py

# Author: wgollino (wgollino@yahoo.com)
# Contributors: ssbarnea
# File: rangevaluesfilterspec.py
# Version: 1.01
#
# Adds filtering by ranges of values in the admin filter sidebar. The example below results in this filter:
#
# By store price
#   All
#   < 100
#   100 - 200
#   200 - 500
#   500 - 2000
#   >= 200
#
#
# Example:
#
# from django.db import models
# import rangevaluesfilterspec
#
# class Product(models.Model):
#     store_price = models.DecimalField(max_digits=10, decimal_places=2)
#     store_price.list_filter_range = [100, 200, 500, 2000]
#
#     class Admin:
#         list_filter = ['store_price']


from django.utils.translation import ugettext as _
from django.utils.safestring import mark_safe
from django.contrib.admin.filterspecs import FilterSpec

class RangeValuesFilterSpec(FilterSpec):
	"""
	Adds filtering by ranges of values in the admin filter sidebar.
	Set range split points in the model field attribute 'list_filter_range'.

	my_model_field.list_filter_range = [100, 200, 300]

	Will define the ranges:
	  my_model_field < 100
	  my_model_field >= 100 AND my_model_field < 200
	  my_model_field >= 200 AND my_model_field < 300
	  my_model_field >= 300
	"""
	def __init__(self, f, request, params, model, model_admin, field_path=None):
		super(RangeValuesFilterSpec, self).__init__(f, request, params, model, model_admin, field_path=field_path)

		self.field_generic = '%s__' % self.field.name
		self.parsed_params = dict([(k, v) for k, v in params.items() if k.startswith(self.field_generic)])

		self.links = [(_('All'), {})]

		last_value = None
		for max_value in sorted(f.list_filter_range):
			max_value = str(max_value)
			if last_value == None:
				label = '&lt; ' + max_value
				range = {'%s__lt' % f.name: max_value}
			else:
				label = last_value + ' - ' + max_value
				range = {'%s__gte' % self.field.name: last_value, '%s__lt' % f.name: max_value}
			self.links.append((_(mark_safe(label)), range))
			last_value = max_value
		self.links.append((_(mark_safe('&ge; ' + max_value)), {'%s__gte' % f.name: max_value}))

	def choices(self, cl):
		for title, param_dict in self.links:
			yield {'selected': self.parsed_params == param_dict,
				   'query_string': cl.get_query_string(param_dict, [self.field_generic]),
				   'display': title}

# register the filter before the default filter
FilterSpec.filter_specs.insert(-1, (lambda f: hasattr(f, 'list_filter_range'), RangeValuesFilterSpec))