# -*- coding: utf-8 -*-
"""
Django-Select2 Widgets.
These components are responsible for rendering
the necessary HTML data markups. Since this whole
package is to render choices using Select2 JavaScript
library, hence these components are meant to be used
with choice fields.
Widgets are generally of two types:
1. **Light** --
They are not meant to be used when there
are too many options, say, in thousands.
This is because all those options would
have to be pre-rendered onto the page
and JavaScript would be used to search
through them. Said that, they are also one
the most easiest to use. They are a
drop-in-replacement for Django's default
select widgets.
2. **Heavy** --
They are suited for scenarios when the number of options
are large and need complex queries (from maybe different
sources) to get the options.
This dynamic fetching of options undoubtedly requires
Ajax communication with the server. Django-Select2 includes
a helper JS file which is included automatically,
so you need not worry about writing any Ajax related JS code.
Although on the server side you do need to create a view
specifically to respond to the queries.
3. **Model** --
Model-widgets are a further specialized versions of Heavies.
These do not require views to serve Ajax requests.
When they are instantiated, they register themselves
with one central view which handles Ajax requests for them.
Heavy widgets have the word 'Heavy' in their name.
Light widgets are normally named, i.e. there is no
'Light' word in their names.
.. inheritance-diagram:: django_select2.forms
:parts: 1
"""
from __future__ import absolute_import, unicode_literals
from functools import reduce
from itertools import chain
from pickle import PicklingError
from django import forms
from django.core import signing
from django.core.urlresolvers import reverse
from django.db.models import Q
from django.forms.models import ModelChoiceIterator
from django.utils.encoding import force_text
from django.utils.six.moves.cPickle import PicklingError as cPicklingError
from .cache import cache
from .conf import settings
[docs]class Select2Mixin(object):
"""
The base mixin of all Select2 widgets.
This mixin is responsible for rendering the necessary
data attributes for select2 as well as adding the static
form media.
"""
[docs] def build_attrs(self, extra_attrs=None, **kwargs):
"""Add select2 data attributes."""
attrs = super(Select2Mixin, self).build_attrs(extra_attrs=extra_attrs, **kwargs)
if self.is_required:
attrs.setdefault('data-allow-clear', 'false')
else:
attrs.setdefault('data-allow-clear', 'true')
attrs.setdefault('data-placeholder', '')
attrs.setdefault('data-minimum-input-length', 0)
if 'class' in attrs:
attrs['class'] += ' django-select2'
else:
attrs['class'] = 'django-select2'
return attrs
[docs] def render_options(self, *args, **kwargs):
"""Render options including an empty one, if the field is not required."""
output = '<option></option>' if not self.is_required and not self.allow_multiple_selected else ''
output += super(Select2Mixin, self).render_options(*args, **kwargs)
return output
def _get_media(self):
"""
Construct Media as a dynamic property.
.. Note:: For more information visit
https://docs.djangoproject.com/en/1.8/topics/forms/media/#media-as-a-dynamic-property
"""
return forms.Media(
js=(settings.SELECT2_JS, 'django_select2/django_select2.js'),
css={'screen': (settings.SELECT2_CSS,)}
)
media = property(_get_media)
[docs]class Select2TagMixin(object):
"""Mixin to add select2 tag functionality."""
[docs] def build_attrs(self, extra_attrs=None, **kwargs):
"""Add select2's tag attributes."""
self.attrs.setdefault('data-minimum-input-length', 1)
self.attrs.setdefault('data-tags', 'true')
self.attrs.setdefault('data-token-separators', '[",", " "]')
return super(Select2TagMixin, self).build_attrs(extra_attrs, **kwargs)
[docs]class HeavySelect2Mixin(object):
"""Mixin that adds select2's AJAX options and registers itself on Django's cache."""
def __init__(self, **kwargs):
"""
Return HeavySelect2Mixin.
Args:
data_view (str): URL pattern name
data_url (str): URL
"""
self.data_view = kwargs.pop('data_view', None)
self.data_url = kwargs.pop('data_url', None)
if not (self.data_view or self.data_url):
raise ValueError('You must ether specify "data_view" or "data_url".')
self.userGetValTextFuncName = kwargs.pop('userGetValTextFuncName', 'null')
super(HeavySelect2Mixin, self).__init__(**kwargs)
[docs] def get_url(self):
"""Return URL from instance or by reversing :attr:`.data_view`."""
if self.data_url:
return self.data_url
return reverse(self.data_view)
[docs] def build_attrs(self, extra_attrs=None, **kwargs):
"""Set select2's AJAX attributes."""
attrs = super(HeavySelect2Mixin, self).build_attrs(extra_attrs=extra_attrs, **kwargs)
# encrypt instance Id
self.widget_id = signing.dumps(id(self))
attrs['data-field_id'] = self.widget_id
attrs.setdefault('data-ajax--url', self.get_url())
attrs.setdefault('data-ajax--cache', "true")
attrs.setdefault('data-ajax--type', "GET")
attrs.setdefault('data-minimum-input-length', 2)
attrs['class'] += ' django-select2-heavy'
return attrs
[docs] def render(self, *args, **kwargs):
"""Render widget and register it in Django's cache."""
output = super(HeavySelect2Mixin, self).render(*args, **kwargs)
self.set_to_cache()
return output
def _get_cache_key(self):
return "%s%s" % (settings.SELECT2_CACHE_PREFIX, id(self))
[docs] def set_to_cache(self):
"""
Add widget object to Django's cache.
You may need to overwrite this method, to pickle all information
that is required to serve your JSON response view.
"""
try:
cache.set(self._get_cache_key(), {
'widget': self,
'url': self.get_url(),
})
except (PicklingError, cPicklingError, AttributeError):
msg = "You need to overwrite \"set_to_cache\" or ensure that %s is serialisable."
raise NotImplementedError(msg % self.__class__.__name__)
[docs] def render_options(self, *args):
"""Render only selected options."""
try:
selected_choices, = args
except ValueError: # Signature contained `choices` prior to Django 1.10
choices, selected_choices = args
choices = chain(self.choices, choices)
else:
choices = self.choices
output = ['<option></option>' if not self.is_required and not self.allow_multiple_selected else '']
selected_choices = {force_text(v) for v in selected_choices}
choices = [(k, v) for k, v in choices if force_text(k) in selected_choices]
for option_value, option_label in choices:
output.append(self.render_option(selected_choices, option_value, option_label))
return '\n'.join(output)
# Auto Heavy widgets
[docs]class ModelSelect2Mixin(object):
"""Widget mixin that provides attributes and methods for :class:`.AutoResponseView`."""
model = None
queryset = None
search_fields = []
"""
Model lookups that are used to filter the QuerySet.
Example::
search_fields = [
'title__icontains',
]
"""
max_results = 25
"""Maximal results returned by :class:`.AutoResponseView`."""
def __init__(self, *args, **kwargs):
"""
Overwrite class parameters if passed as keyword arguments.
Args:
model (django.db.models.Model): Model to select choices from.
queryset (django.db.models.QuerySet): QuerySet to select choices from.
search_fields (list): List of model lookup strings.
max_results (int): Max. JsonResponse view page size.
"""
self.model = kwargs.pop('model', self.model)
self.queryset = kwargs.pop('queryset', self.queryset)
self.search_fields = kwargs.pop('search_fields', self.search_fields)
self.max_results = kwargs.pop('max_results', self.max_results)
defaults = {'data_view': 'django_select2-json'}
defaults.update(kwargs)
super(ModelSelect2Mixin, self).__init__(*args, **defaults)
[docs] def set_to_cache(self):
"""
Add widget's attributes to Django's cache.
Split the QuerySet, to not pickle the result set.
"""
queryset = self.get_queryset()
cache.set(self._get_cache_key(), {
'queryset':
[
queryset.none(),
queryset.query,
],
'cls': self.__class__,
'search_fields': self.search_fields,
'max_results': self.max_results,
'url': self.get_url(),
})
[docs] def filter_queryset(self, term, queryset=None):
"""
Return QuerySet filtered by search_fields matching the passed term.
Args:
term (str): Search term
Returns:
QuerySet: Filtered QuerySet
"""
if queryset is None:
queryset = self.get_queryset()
search_fields = self.get_search_fields()
select = Q()
term = term.replace('\t', ' ')
term = term.replace('\n', ' ')
for t in [t for t in term.split(' ') if not t == '']:
select &= reduce(lambda x, y: x | Q(**{y: t}), search_fields,
Q(**{search_fields[0]: t}))
return queryset.filter(select).distinct()
[docs] def get_queryset(self):
"""
Return QuerySet based on :attr:`.queryset` or :attr:`.model`.
Returns:
QuerySet: QuerySet of available choices.
"""
if self.queryset is not None:
queryset = self.queryset
elif self.model is not None:
queryset = self.model._default_manager.all()
else:
raise NotImplementedError(
"%(cls)s is missing a QuerySet. Define "
"%(cls)s.model, %(cls)s.queryset, or override "
"%(cls)s.get_queryset()." % {
'cls': self.__class__.__name__
}
)
return queryset
[docs] def get_search_fields(self):
"""Return list of lookup names."""
if self.search_fields:
return self.search_fields
raise NotImplementedError('%s, must implement "search_fields".' % self.__class__.__name__)
[docs] def render_options(self, *args):
"""Render only selected options and set QuerySet from :class:`ModelChoicesIterator`."""
try:
selected_choices, = args
except ValueError:
choices, selected_choices = args
choices = chain(self.choices, choices)
else:
choices = self.choices
selected_choices = {force_text(v) for v in selected_choices}
output = ['<option></option>' if not self.is_required and not self.allow_multiple_selected else '']
if isinstance(self.choices, ModelChoiceIterator):
if self.queryset is None:
self.queryset = self.choices.queryset
selected_choices = {c for c in selected_choices
if c not in self.choices.field.empty_values}
choices = [(obj.pk, self.label_from_instance(obj))
for obj in self.choices.queryset.filter(pk__in=selected_choices)]
else:
choices = [(k, v) for k, v in choices if force_text(k) in selected_choices]
for option_value, option_label in choices:
output.append(self.render_option(selected_choices, option_value, option_label))
return '\n'.join(output)
[docs] def label_from_instance(self, obj):
"""
Return option label representation from instance.
Can be overridden to change the representation of each choice.
Example usage::
class MyWidget(ModelSelect2Widget):
def label_from_instance(obj):
return force_text(obj.title).upper()
Args:
obj (django.db.models.Model): Instance of Django Model.
Returns:
str: Option label.
"""
return force_text(obj)