root/django/trunk/django/forms/models.py

"""
Helper functions for creating Form classes from Django models
and database field objects.
"""

from django.utils.encoding import smart_unicode, force_unicode
from django.utils.datastructures import SortedDict
from django.utils.text import get_text_list, capfirst
from django.utils.translation import ugettext_lazy as _

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

try:
    set
except NameError:
    from sets import Set as set     # Python 2.3 fallback

__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, exclude=None):
    """
    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
    file_field_list = []
    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
        if exclude and f.name in exclude:
            continue
        # Defer saving file-type fields until after the other fields, so a
        # callable upload_to can use the values from other fields.
        if isinstance(f, models.FileField):
            file_field_list.append(f)
        else:
            f.save_form_data(instance, cleaned_data[f.name])

    for f in file_field_list:
        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)]
        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
        declared_fields = get_declared_fields(bases, attrs, False)
        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)
        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 clean(self):
        self.validate_unique()
        return self.cleaned_data

    def validate_unique(self):
        from django.db.models.fields import FieldDoesNotExist

        # Gather a list of checks to perform. We only perform unique checks
        # for fields present and not None in cleaned_data.  Since this is a
        # ModelForm, some fields may have been excluded; we can't perform a unique
        # check on a form that is missing fields involved in that check.  It also does
        # not make sense to check data that didn't validate, and since NULL does not
        # equal NULL in SQL we should not do any unique checking for NULL values.
        unique_checks = []
        for check in self.instance._meta.unique_together[:]:
            fields_on_form = [field for field in check if self.cleaned_data.get(field) is not None]
            if len(fields_on_form) == len(check):
                unique_checks.append(check)

        form_errors = []

        # Gather a list of checks for fields declared as unique and add them to
        # the list of checks. Again, skip empty fields and any that did not validate.
        for name, field in self.fields.items():
            try:
                f = self.instance._meta.get_field_by_name(name)[0]
            except FieldDoesNotExist:
                # This is an extra field that's not on the ModelForm, ignore it
                continue
            if f.unique and self.cleaned_data.get(name) is not None:
                unique_checks.append((name,))

        bad_fields = set()
        for unique_check in unique_checks:
            # Try to look up an existing object with the same values as this
            # object's values for all the unique field.

            lookup_kwargs = {}
            for field_name in unique_check:
                lookup_kwargs[field_name] = self.cleaned_data[field_name]

            qs = self.instance.__class__._default_manager.filter(**lookup_kwargs)

            # Exclude the current object from the query if we are editing an
            # instance (as opposed to creating a new one)
            if self.instance.pk is not None:
                qs = qs.exclude(pk=self.instance.pk)

            # This cute trick with extra/values is the most efficient way to
            # tell if a particular query returns any results.
            if qs.extra(select={'a': 1}).values('a').order_by():
                model_name = capfirst(self.instance._meta.verbose_name)

                # A unique field
                if len(unique_check) == 1:
                    field_name = unique_check[0]
                    field_label = self.fields[field_name].label
                    # Insert the error into the error dict, very sneaky
                    self._errors[field_name] = ErrorList([
                        _(u"%(model_name)s with this %(field_label)s already exists.") % \
                        {'model_name': unicode(model_name),
                         'field_label': unicode(field_label)}
                    ])
                # unique_together
                else:
                    field_labels = [self.fields[field_name].label for field_name in unique_check]
                    field_labels = get_text_list(field_labels, _('and'))
                    form_errors.append(
                        _(u"%(model_name)s with this %(field_label)s already exists.") % \
                        {'model_name': unicode(model_name),
                         'field_label': unicode(field_labels)}
                    )

                # Mark these fields as needing to be removed from cleaned data
                # later.
                for field_name in unique_check:
                    bad_fields.add(field_name)

        for field_name in bad_fields:
            del self.cleaned_data[field_name]
        if form_errors:
            # Raise the unique together errors since they are considered
            # form-wide.
            raise ValidationError(form_errors)

    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)

    save.alters_data = True

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}
        defaults['initial'] = [model_to_dict(obj) for obj in self.get_queryset()]
        defaults.update(kwargs)
        super(BaseModelFormSet, self).__init__(**defaults)

    def _construct_form(self, i, **kwargs):
        if i < self._initial_form_count:
            kwargs['instance'] = self.get_queryset()[i]
        return super(BaseModelFormSet, self)._construct_form(i, **kwargs)

    def get_queryset(self):
        if not hasattr(self, '_queryset'):
            if self.queryset is not None:
                qs = self.queryset
            else:
                qs = self.model._default_manager.get_query_set()
            if self.max_num > 0:
                self._queryset = qs[:self.max_num]
            else:
                self._queryset = qs
        return self._queryset

    def save_new(self, form, commit=True):
        """Saves and returns a new model instance for the given form."""
        return save_instance(form, self.model(), exclude=[self._pk_field.name], 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, exclude=[self._pk_field.name], 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._pk_field.name]]
            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."""
        from django.db.models import AutoField
        self._pk_field = pk = self.model._meta.pk
        if pk.auto_created or isinstance(pk, AutoField):
            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
        if instance is None:
            self.instance = self.model()
        else:
            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()
        qs = self.model._default_manager.filter(**{self.fk.name: self.instance})
        super(BaseInlineFormSet, self).__init__(data, files, prefix=prefix or self.rel_name,
                                                queryset=qs)

    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 _construct_form(self, i, **kwargs):
        form = super(BaseInlineFormSet, self)._construct_form(i, **kwargs)
        if self.save_as_new:
            # Remove the primary key from the form's data, we are only
            # creating new instances
            form.data[form.add_prefix(self._pk_field.name)] = None
        return form

    def save_new(self, form, commit=True):
        fk_attname = self.fk.get_attname()
        kwargs = {fk_attname: self.instance.pk}
        new_obj = self.model(**kwargs)
        if fk_attname == self._pk_field.attname:
            exclude =  [self._pk_field.name]
        else:
            exclude = []