def render_options(self, *args):
"""Render only selected options and set QuerySet from :class:`ModelChoiceIterator`."""
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)
python类ModelChoiceIterator()的实例源码
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):
# Mejora significativa de rendimiernto con esta condición
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)
def __init__(self, *args, **kwargs):
queryset = kwargs.pop('queryset', None)
self.many = kwargs.pop('many', self.many)
if self.many:
self.widget = self.many_widget
self.form_field_class = self.many_form_field_class
kwargs['read_only'] = kwargs.pop('read_only', self.read_only)
super(RelatedField, self).__init__(*args, **kwargs)
if not self.required:
# Accessed in ModelChoiceIterator django/forms/models.py:1034
# If set adds empty choice.
self.empty_label = BLANK_CHOICE_DASH[0][1]
self.queryset = queryset
def choices(self, value):
""" ??????????? ??????, ?? ??????? ???????????? ??????? """
self._choices = value
if isinstance(value, ModelChoiceIterator):
self.app_label = value.queryset.model._meta.app_label
self.model_name = value.queryset.model._meta.model_name
else:
raise TypeError('choices for AutocompleteWidget must be an instance of ModelChoiceIterator')
def _get_choices(self):
# If self._choices is set, then somebody must have manually set
# the property self.choices. In this case, just return self._choices.
if hasattr(self, '_choices'):
return self._choices
# Otherwise, execute the QuerySet in self.queryset to determine the
# choices dynamically. Return a fresh ModelChoiceIterator that has not been
# consumed. Note that we're instantiating a new ModelChoiceIterator *each*
# time _get_choices() is called (and, thus, each time self.choices is
# accessed) so that we can ensure the QuerySet has not been consumed. This
# construct might look complicated but it allows for lazy evaluation of
# the queryset.
return ModelChoiceIterator(self)
