""" 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 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