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models.py
616 lines (542 loc) · 24.5 KB
/
models.py
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"""
Helper functions for creating Form classes from Django models
and database field objects.
"""
from warnings import warn
from django.utils.translation import ugettext_lazy as _
from django.utils.encoding import smart_unicode
from django.utils.datastructures import SortedDict
from util import ValidationError, ErrorList
from forms import BaseForm, get_declared_fields
from fields import Field, ChoiceField, IntegerField, EMPTY_VALUES
from widgets import Select, SelectMultiple, HiddenInput, MultipleHiddenInput
from widgets import media_property
from formsets import BaseFormSet, formset_factory, DELETION_FIELD_NAME
__all__ = (
'ModelForm', 'BaseModelForm', 'model_to_dict', 'fields_for_model',
'save_instance', 'form_for_model', 'form_for_instance', 'form_for_fields',
'ModelChoiceField', 'ModelMultipleChoiceField',
)
def save_instance(form, instance, fields=None, fail_message='saved',
commit=True):
"""
Saves bound Form ``form``'s cleaned_data into model instance ``instance``.
If commit=True, then the changes to ``instance`` will be saved to the
database. Returns ``instance``.
"""
from django.db import models
opts = instance._meta
if form.errors:
raise ValueError("The %s could not be %s because the data didn't"
" validate." % (opts.object_name, fail_message))
cleaned_data = form.cleaned_data
for f in opts.fields:
if not f.editable or isinstance(f, models.AutoField) \
or not f.name in cleaned_data:
continue
if fields and f.name not in fields:
continue
f.save_form_data(instance, cleaned_data[f.name])
# Wrap up the saving of m2m data as a function.
def save_m2m():
opts = instance._meta
cleaned_data = form.cleaned_data
for f in opts.many_to_many:
if fields and f.name not in fields:
continue
if f.name in cleaned_data:
f.save_form_data(instance, cleaned_data[f.name])
if commit:
# If we are committing, save the instance and the m2m data immediately.
instance.save()
save_m2m()
else:
# We're not committing. Add a method to the form to allow deferred
# saving of m2m data.
form.save_m2m = save_m2m
return instance
def make_model_save(model, fields, fail_message):
"""Returns the save() method for a Form."""
def save(self, commit=True):
return save_instance(self, model(), fields, fail_message, commit)
return save
def make_instance_save(instance, fields, fail_message):
"""Returns the save() method for a Form."""
def save(self, commit=True):
return save_instance(self, instance, fields, fail_message, commit)
return save
def form_for_model(model, form=BaseForm, fields=None,
formfield_callback=lambda f: f.formfield()):
"""
Returns a Form class for the given Django model class.
Provide ``form`` if you want to use a custom BaseForm subclass.
Provide ``formfield_callback`` if you want to define different logic for
determining the formfield for a given database field. It's a callable that
takes a database Field instance and returns a form Field instance.
"""
warn("form_for_model is deprecated. Use ModelForm instead.",
PendingDeprecationWarning, stacklevel=3)
opts = model._meta
field_list = []
for f in opts.fields + opts.many_to_many:
if not f.editable:
continue
if fields and not f.name in fields:
continue
formfield = formfield_callback(f)
if formfield:
field_list.append((f.name, formfield))
base_fields = SortedDict(field_list)
return type(opts.object_name + 'Form', (form,),
{'base_fields': base_fields, '_model': model,
'save': make_model_save(model, fields, 'created')})
def form_for_instance(instance, form=BaseForm, fields=None,
formfield_callback=lambda f, **kwargs: f.formfield(**kwargs)):
"""
Returns a Form class for the given Django model instance.
Provide ``form`` if you want to use a custom BaseForm subclass.
Provide ``formfield_callback`` if you want to define different logic for
determining the formfield for a given database field. It's a callable that
takes a database Field instance, plus **kwargs, and returns a form Field
instance with the given kwargs (i.e. 'initial').
"""
warn("form_for_instance is deprecated. Use ModelForm instead.",
PendingDeprecationWarning, stacklevel=3)
model = instance.__class__
opts = model._meta
field_list = []
for f in opts.fields + opts.many_to_many:
if not f.editable:
continue
if fields and not f.name in fields:
continue
current_value = f.value_from_object(instance)
formfield = formfield_callback(f, initial=current_value)
if formfield:
field_list.append((f.name, formfield))
base_fields = SortedDict(field_list)
return type(opts.object_name + 'InstanceForm', (form,),
{'base_fields': base_fields, '_model': model,
'save': make_instance_save(instance, fields, 'changed')})
def form_for_fields(field_list):
"""
Returns a Form class for the given list of Django database field instances.
"""
fields = SortedDict([(f.name, f.formfield())
for f in field_list if f.editable])
return type('FormForFields', (BaseForm,), {'base_fields': fields})
# ModelForms #################################################################
def model_to_dict(instance, fields=None, exclude=None):
"""
Returns a dict containing the data in ``instance`` suitable for passing as
a Form's ``initial`` keyword argument.
``fields`` is an optional list of field names. If provided, only the named
fields will be included in the returned dict.
``exclude`` is an optional list of field names. If provided, the named
fields will be excluded from the returned dict, even if they are listed in
the ``fields`` argument.
"""
# avoid a circular import
from django.db.models.fields.related import ManyToManyField
opts = instance._meta
data = {}
for f in opts.fields + opts.many_to_many:
if not f.editable:
continue
if fields and not f.name in fields:
continue
if exclude and f.name in exclude:
continue
if isinstance(f, ManyToManyField):
# If the object doesn't have a primry key yet, just use an empty
# list for its m2m fields. Calling f.value_from_object will raise
# an exception.
if instance.pk is None:
data[f.name] = []
else:
# MultipleChoiceWidget needs a list of pks, not object instances.
data[f.name] = [obj.pk for obj in f.value_from_object(instance)]
else:
data[f.name] = f.value_from_object(instance)
return data
def fields_for_model(model, fields=None, exclude=None, formfield_callback=lambda f: f.formfield()):
"""
Returns a ``SortedDict`` containing form fields for the given model.
``fields`` is an optional list of field names. If provided, only the named
fields will be included in the returned fields.
``exclude`` is an optional list of field names. If provided, the named
fields will be excluded from the returned fields, even if they are listed
in the ``fields`` argument.
"""
# TODO: if fields is provided, it would be nice to return fields in that order
field_list = []
opts = model._meta
for f in opts.fields + opts.many_to_many:
if not f.editable:
continue
if fields and not f.name in fields:
continue
if exclude and f.name in exclude:
continue
formfield = formfield_callback(f)
if formfield:
field_list.append((f.name, formfield))
return SortedDict(field_list)
class ModelFormOptions(object):
def __init__(self, options=None):
self.model = getattr(options, 'model', None)
self.fields = getattr(options, 'fields', None)
self.exclude = getattr(options, 'exclude', None)
class ModelFormMetaclass(type):
def __new__(cls, name, bases, attrs):
formfield_callback = attrs.pop('formfield_callback',
lambda f: f.formfield())
try:
parents = [b for b in bases if issubclass(b, ModelForm)]
except NameError:
# We are defining ModelForm itself.
parents = None
new_class = super(ModelFormMetaclass, cls).__new__(cls, name, bases,
attrs)
if not parents:
return new_class
if 'media' not in attrs:
new_class.media = media_property(new_class)
declared_fields = get_declared_fields(bases, attrs, False)
opts = new_class._meta = ModelFormOptions(getattr(new_class, 'Meta', None))
if opts.model:
# If a model is defined, extract form fields from it.
fields = fields_for_model(opts.model, opts.fields,
opts.exclude, formfield_callback)
# Override default model fields with any custom declared ones
# (plus, include all the other declared fields).
fields.update(declared_fields)
else:
fields = declared_fields
new_class.declared_fields = declared_fields
new_class.base_fields = fields
return new_class
class BaseModelForm(BaseForm):
def __init__(self, data=None, files=None, auto_id='id_%s', prefix=None,
initial=None, error_class=ErrorList, label_suffix=':',
empty_permitted=False, instance=None):
opts = self._meta
if instance is None:
# if we didn't get an instance, instantiate a new one
self.instance = opts.model()
object_data = {}
else:
self.instance = instance
object_data = model_to_dict(instance, opts.fields, opts.exclude)
# if initial was provided, it should override the values from instance
if initial is not None:
object_data.update(initial)
super(BaseModelForm, self).__init__(data, files, auto_id, prefix, object_data,
error_class, label_suffix, empty_permitted)
def save(self, commit=True):
"""
Saves this ``form``'s cleaned_data into model instance
``self.instance``.
If commit=True, then the changes to ``instance`` will be saved to the
database. Returns ``instance``.
"""
if self.instance.pk is None:
fail_message = 'created'
else:
fail_message = 'changed'
return save_instance(self, self.instance, self._meta.fields, fail_message, commit)
class ModelForm(BaseModelForm):
__metaclass__ = ModelFormMetaclass
def modelform_factory(model, form=ModelForm, fields=None, exclude=None,
formfield_callback=lambda f: f.formfield()):
# HACK: we should be able to construct a ModelForm without creating
# and passing in a temporary inner class
class Meta:
pass
setattr(Meta, 'model', model)
setattr(Meta, 'fields', fields)
setattr(Meta, 'exclude', exclude)
class_name = model.__name__ + 'Form'
return ModelFormMetaclass(class_name, (form,), {'Meta': Meta,
'formfield_callback': formfield_callback})
# ModelFormSets ##############################################################
class BaseModelFormSet(BaseFormSet):
"""
A ``FormSet`` for editing a queryset and/or adding new objects to it.
"""
model = None
def __init__(self, data=None, files=None, auto_id='id_%s', prefix=None,
queryset=None, **kwargs):
self.queryset = queryset
defaults = {'data': data, 'files': files, 'auto_id': auto_id, 'prefix': prefix}
if self.max_num > 0:
qs = self.get_queryset()[:self.max_num]
else:
qs = self.get_queryset()
defaults['initial'] = [model_to_dict(obj) for obj in qs]
defaults.update(kwargs)
super(BaseModelFormSet, self).__init__(**defaults)
def get_queryset(self):
if self.queryset is not None:
return self.queryset
return self.model._default_manager.get_query_set()
def save_new(self, form, commit=True):
"""Saves and returns a new model instance for the given form."""
return save_instance(form, self.model(), commit=commit)
def save_existing(self, form, instance, commit=True):
"""Saves and returns an existing model instance for the given form."""
return save_instance(form, instance, commit=commit)
def save(self, commit=True):
"""Saves model instances for every form, adding and changing instances
as necessary, and returns the list of instances.
"""
if not commit:
self.saved_forms = []
def save_m2m():
for form in self.saved_forms:
form.save_m2m()
self.save_m2m = save_m2m
return self.save_existing_objects(commit) + self.save_new_objects(commit)
def save_existing_objects(self, commit=True):
self.changed_objects = []
self.deleted_objects = []
if not self.get_queryset():
return []
# Put the objects from self.get_queryset into a dict so they are easy to lookup by pk
existing_objects = {}
for obj in self.get_queryset():
existing_objects[obj.pk] = obj
saved_instances = []
for form in self.initial_forms:
obj = existing_objects[form.cleaned_data[self.model._meta.pk.attname]]
if self.can_delete and form.cleaned_data[DELETION_FIELD_NAME]:
self.deleted_objects.append(obj)
obj.delete()
else:
if form.changed_data:
self.changed_objects.append((obj, form.changed_data))
saved_instances.append(self.save_existing(form, obj, commit=commit))
if not commit:
self.saved_forms.append(form)
return saved_instances
def save_new_objects(self, commit=True):
self.new_objects = []
for form in self.extra_forms:
if not form.has_changed():
continue
# If someone has marked an add form for deletion, don't save the
# object.
if self.can_delete and form.cleaned_data[DELETION_FIELD_NAME]:
continue
self.new_objects.append(self.save_new(form, commit=commit))
if not commit:
self.saved_forms.append(form)
return self.new_objects
def add_fields(self, form, index):
"""Add a hidden field for the object's primary key."""
if self.model._meta.has_auto_field:
self._pk_field_name = self.model._meta.pk.attname
form.fields[self._pk_field_name] = IntegerField(required=False, widget=HiddenInput)
super(BaseModelFormSet, self).add_fields(form, index)
def modelformset_factory(model, form=ModelForm, formfield_callback=lambda f: f.formfield(),
formset=BaseModelFormSet,
extra=1, can_delete=False, can_order=False,
max_num=0, fields=None, exclude=None):
"""
Returns a FormSet class for the given Django model class.
"""
form = modelform_factory(model, form=form, fields=fields, exclude=exclude,
formfield_callback=formfield_callback)
FormSet = formset_factory(form, formset, extra=extra, max_num=max_num,
can_order=can_order, can_delete=can_delete)
FormSet.model = model
return FormSet
# InlineFormSets #############################################################
class BaseInlineFormset(BaseModelFormSet):
"""A formset for child objects related to a parent."""
def __init__(self, data=None, files=None, instance=None,
save_as_new=False, prefix=None):
from django.db.models.fields.related import RelatedObject
self.instance = instance
self.save_as_new = save_as_new
# is there a better way to get the object descriptor?
self.rel_name = RelatedObject(self.fk.rel.to, self.model, self.fk).get_accessor_name()
super(BaseInlineFormset, self).__init__(data, files, prefix=prefix or self.rel_name)
def _construct_forms(self):
if self.save_as_new:
self._total_form_count = self._initial_form_count
self._initial_form_count = 0
super(BaseInlineFormset, self)._construct_forms()
def get_queryset(self):
"""
Returns this FormSet's queryset, but restricted to children of
self.instance
"""
kwargs = {self.fk.name: self.instance}
return self.model._default_manager.filter(**kwargs)
def save_new(self, form, commit=True):
kwargs = {self.fk.get_attname(): self.instance.pk}
new_obj = self.model(**kwargs)
return save_instance(form, new_obj, commit=commit)
def _get_foreign_key(parent_model, model, fk_name=None):
"""
Finds and returns the ForeignKey from model to parent if there is one.
If fk_name is provided, assume it is the name of the ForeignKey field.
"""
# avoid circular import
from django.db.models import ForeignKey
opts = model._meta
if fk_name:
fks_to_parent = [f for f in opts.fields if f.name == fk_name]
if len(fks_to_parent) == 1:
fk = fks_to_parent[0]
if not isinstance(fk, ForeignKey) or \
(fk.rel.to != parent_model and
fk.rel.to not in parent_model._meta.parents.keys()):
raise Exception("fk_name '%s' is not a ForeignKey to %s" % (fk_name, parent_model))
elif len(fks_to_parent) == 0:
raise Exception("%s has no field named '%s'" % (model, fk_name))
else:
# Try to discover what the ForeignKey from model to parent_model is
fks_to_parent = [
f for f in opts.fields
if isinstance(f, ForeignKey)
and (f.rel.to == parent_model
or f.rel.to in parent_model._meta.parents.keys())
]
if len(fks_to_parent) == 1:
fk = fks_to_parent[0]
elif len(fks_to_parent) == 0:
raise Exception("%s has no ForeignKey to %s" % (model, parent_model))
else:
raise Exception("%s has more than 1 ForeignKey to %s" % (model, parent_model))
return fk
def inlineformset_factory(parent_model, model, form=ModelForm,
formset=BaseInlineFormset, fk_name=None,
fields=None, exclude=None,
extra=3, can_order=False, can_delete=True, max_num=0,
formfield_callback=lambda f: f.formfield()):
"""
Returns an ``InlineFormset`` for the given kwargs.
You must provide ``fk_name`` if ``model`` has more than one ``ForeignKey``
to ``parent_model``.
"""
fk = _get_foreign_key(parent_model, model, fk_name=fk_name)
# let the formset handle object deletion by default
if exclude is not None:
exclude.append(fk.name)
else:
exclude = [fk.name]
FormSet = modelformset_factory(model, form=form,
formfield_callback=formfield_callback,
formset=formset,
extra=extra, can_delete=can_delete, can_order=can_order,
fields=fields, exclude=exclude, max_num=max_num)
FormSet.fk = fk
return FormSet
# Fields #####################################################################
class ModelChoiceIterator(object):
def __init__(self, field):
self.field = field
self.queryset = field.queryset
def __iter__(self):
if self.field.empty_label is not None:
yield (u"", self.field.empty_label)
if self.field.cache_choices:
if self.field.choice_cache is None:
self.field.choice_cache = [
(obj.pk, self.field.label_from_instance(obj))
for obj in self.queryset.all()
]
for choice in self.field.choice_cache:
yield choice
else:
for obj in self.queryset.all():
yield (obj.pk, self.field.label_from_instance(obj))
class ModelChoiceField(ChoiceField):
"""A ChoiceField whose choices are a model QuerySet."""
# This class is a subclass of ChoiceField for purity, but it doesn't
# actually use any of ChoiceField's implementation.
default_error_messages = {
'invalid_choice': _(u'Select a valid choice. That choice is not one of'
u' the available choices.'),
}
def __init__(self, queryset, empty_label=u"---------", cache_choices=False,
required=True, widget=Select, label=None, initial=None,
help_text=None, *args, **kwargs):
self.empty_label = empty_label
self.cache_choices = cache_choices
# Call Field instead of ChoiceField __init__() because we don't need
# ChoiceField.__init__().
Field.__init__(self, required, widget, label, initial, help_text,
*args, **kwargs)
self.queryset = queryset
self.choice_cache = None
def _get_queryset(self):
return self._queryset
def _set_queryset(self, queryset):
self._queryset = queryset
self.widget.choices = self.choices
queryset = property(_get_queryset, _set_queryset)
# this method will be used to create object labels by the QuerySetIterator.
# Override it to customize the label.
def label_from_instance(self, obj):
"""
This method is used to convert objects into strings; it's used to
generate the labels for the choices presented by this object. Subclasses
can override this method to customize the display of the choices.
"""
return smart_unicode(obj)
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 QuerySetIterator that has not been
# consumed. Note that we're instantiating a new QuerySetIterator *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)
choices = property(_get_choices, ChoiceField._set_choices)
def clean(self, value):
Field.clean(self, value)
if value in EMPTY_VALUES:
return None
try:
value = self.queryset.get(pk=value)
except self.queryset.model.DoesNotExist:
raise ValidationError(self.error_messages['invalid_choice'])
return value
class ModelMultipleChoiceField(ModelChoiceField):
"""A MultipleChoiceField whose choices are a model QuerySet."""
hidden_widget = MultipleHiddenInput
default_error_messages = {
'list': _(u'Enter a list of values.'),
'invalid_choice': _(u'Select a valid choice. %s is not one of the'
u' available choices.'),
}
def __init__(self, queryset, cache_choices=False, required=True,
widget=SelectMultiple, label=None, initial=None,
help_text=None, *args, **kwargs):
super(ModelMultipleChoiceField, self).__init__(queryset, None,
cache_choices, required, widget, label, initial, help_text,
*args, **kwargs)
def clean(self, value):
if self.required and not value:
raise ValidationError(self.error_messages['required'])
elif not self.required and not value:
return []
if not isinstance(value, (list, tuple)):
raise ValidationError(self.error_messages['list'])
final_values = []
for val in value:
try:
obj = self.queryset.get(pk=val)
except self.queryset.model.DoesNotExist:
raise ValidationError(self.error_messages['invalid_choice'] % val)
else:
final_values.append(obj)
return final_values