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Diffstat (limited to 'webapp/django/forms/models.py')
| -rw-r--r-- | webapp/django/forms/models.py | 558 |
1 files changed, 558 insertions, 0 deletions
diff --git a/webapp/django/forms/models.py b/webapp/django/forms/models.py new file mode 100644 index 0000000000..677556d91b --- /dev/null +++ b/webapp/django/forms/models.py @@ -0,0 +1,558 @@ +""" +Helper functions for creating Form classes from Django models +and database field objects. +""" + +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_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_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, OneToOneField + 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)] + elif isinstance(f, OneToOneField): + data[f.attname] = 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.pk.auto_created: + 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=None, 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.""" + widget = SelectMultiple + 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=None, 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 |