207 lines
8.6 KiB
Python
207 lines
8.6 KiB
Python
"""
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Helper functions for creating Form classes from Django models
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and database field objects.
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"""
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from django.utils.translation import ugettext
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from django.utils.encoding import smart_unicode
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from util import ValidationError
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from forms import BaseForm, SortedDictFromList
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from fields import Field, ChoiceField
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from widgets import Select, SelectMultiple, MultipleHiddenInput
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__all__ = (
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'save_instance', 'form_for_model', 'form_for_instance', 'form_for_fields',
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'ModelChoiceField', 'ModelMultipleChoiceField'
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)
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def save_instance(form, instance, fields=None, fail_message='saved', commit=True):
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"""
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Saves bound Form ``form``'s cleaned_data into model instance ``instance``.
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If commit=True, then the changes to ``instance`` will be saved to the
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database. Returns ``instance``.
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"""
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from django.db import models
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opts = instance.__class__._meta
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if form.errors:
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raise ValueError("The %s could not be %s because the data didn't validate." % (opts.object_name, fail_message))
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cleaned_data = form.cleaned_data
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for f in opts.fields:
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if not f.editable or isinstance(f, models.AutoField) or not f.name in cleaned_data:
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continue
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if fields and f.name not in fields:
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continue
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setattr(instance, f.name, cleaned_data[f.name])
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# Wrap up the saving of m2m data as a function
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def save_m2m():
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opts = instance.__class__._meta
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cleaned_data = form.cleaned_data
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for f in opts.many_to_many:
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if fields and f.name not in fields:
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continue
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if f.name in cleaned_data:
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setattr(instance, f.attname, cleaned_data[f.name])
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if commit:
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# If we are committing, save the instance and the m2m data immediately
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instance.save()
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save_m2m()
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else:
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# We're not committing. Add a method to the form to allow deferred
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# saving of m2m data
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form.save_m2m = save_m2m
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return instance
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def make_model_save(model, fields, fail_message):
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"Returns the save() method for a Form."
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def save(self, commit=True):
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return save_instance(self, model(), fields, fail_message, commit)
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return save
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def make_instance_save(instance, fields, fail_message):
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"Returns the save() method for a Form."
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def save(self, commit=True):
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return save_instance(self, instance, fields, fail_message, commit)
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return save
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def form_for_model(model, form=BaseForm, fields=None, formfield_callback=lambda f: f.formfield()):
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"""
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Returns a Form class for the given Django model class.
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Provide ``form`` if you want to use a custom BaseForm subclass.
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Provide ``formfield_callback`` if you want to define different logic for
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determining the formfield for a given database field. It's a callable that
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takes a database Field instance and returns a form Field instance.
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"""
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opts = model._meta
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field_list = []
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for f in opts.fields + opts.many_to_many:
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if not f.editable:
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continue
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if fields and not f.name in fields:
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continue
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formfield = formfield_callback(f)
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if formfield:
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field_list.append((f.name, formfield))
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base_fields = SortedDictFromList(field_list)
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return type(opts.object_name + 'Form', (form,),
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{'base_fields': base_fields, '_model': model, 'save': make_model_save(model, fields, 'created')})
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def form_for_instance(instance, form=BaseForm, fields=None, formfield_callback=lambda f, **kwargs: f.formfield(**kwargs)):
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"""
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Returns a Form class for the given Django model instance.
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Provide ``form`` if you want to use a custom BaseForm subclass.
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Provide ``formfield_callback`` if you want to define different logic for
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determining the formfield for a given database field. It's a callable that
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takes a database Field instance, plus **kwargs, and returns a form Field
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instance with the given kwargs (i.e. 'initial').
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"""
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model = instance.__class__
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opts = model._meta
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field_list = []
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for f in opts.fields + opts.many_to_many:
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if not f.editable:
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continue
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if fields and not f.name in fields:
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continue
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current_value = f.value_from_object(instance)
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formfield = formfield_callback(f, initial=current_value)
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if formfield:
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field_list.append((f.name, formfield))
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base_fields = SortedDictFromList(field_list)
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return type(opts.object_name + 'InstanceForm', (form,),
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{'base_fields': base_fields, '_model': model, 'save': make_instance_save(instance, fields, 'changed')})
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def form_for_fields(field_list):
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"Returns a Form class for the given list of Django database field instances."
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fields = SortedDictFromList([(f.name, f.formfield()) for f in field_list if f.editable])
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return type('FormForFields', (BaseForm,), {'base_fields': fields})
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class QuerySetIterator(object):
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def __init__(self, queryset, empty_label, cache_choices):
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self.queryset, self.empty_label, self.cache_choices = queryset, empty_label, cache_choices
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def __iter__(self):
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if self.empty_label is not None:
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yield (u"", self.empty_label)
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for obj in self.queryset:
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yield (obj._get_pk_val(), smart_unicode(obj))
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# Clear the QuerySet cache if required.
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if not self.cache_choices:
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self.queryset._result_cache = None
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class ModelChoiceField(ChoiceField):
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"A ChoiceField whose choices are a model QuerySet."
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# This class is a subclass of ChoiceField for purity, but it doesn't
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# actually use any of ChoiceField's implementation.
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def __init__(self, queryset, empty_label=u"---------", cache_choices=False,
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required=True, widget=Select, label=None, initial=None, help_text=None):
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self.queryset = queryset
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self.empty_label = empty_label
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self.cache_choices = cache_choices
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# Call Field instead of ChoiceField __init__() because we don't need
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# ChoiceField.__init__().
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Field.__init__(self, required, widget, label, initial, help_text)
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self.widget.choices = self.choices
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def _get_choices(self):
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# If self._choices is set, then somebody must have manually set
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# the property self.choices. In this case, just return self._choices.
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if hasattr(self, '_choices'):
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return self._choices
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# Otherwise, execute the QuerySet in self.queryset to determine the
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# choices dynamically. Return a fresh QuerySetIterator that has not
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# been consumed. Note that we're instantiating a new QuerySetIterator
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# *each* time _get_choices() is called (and, thus, each time
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# self.choices is accessed) so that we can ensure the QuerySet has not
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# been consumed.
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return QuerySetIterator(self.queryset, self.empty_label, self.cache_choices)
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def _set_choices(self, value):
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# This method is copied from ChoiceField._set_choices(). It's necessary
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# because property() doesn't allow a subclass to overwrite only
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# _get_choices without implementing _set_choices.
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self._choices = self.widget.choices = list(value)
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choices = property(_get_choices, _set_choices)
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def clean(self, value):
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Field.clean(self, value)
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if value in ('', None):
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return None
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try:
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value = self.queryset.model._default_manager.get(pk=value)
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except self.queryset.model.DoesNotExist:
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raise ValidationError(ugettext(u'Select a valid choice. That choice is not one of the available choices.'))
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return value
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class ModelMultipleChoiceField(ModelChoiceField):
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"A MultipleChoiceField whose choices are a model QuerySet."
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hidden_widget = MultipleHiddenInput
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def __init__(self, queryset, cache_choices=False, required=True,
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widget=SelectMultiple, label=None, initial=None, help_text=None):
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super(ModelMultipleChoiceField, self).__init__(queryset, None, cache_choices,
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required, widget, label, initial, help_text)
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def clean(self, value):
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if self.required and not value:
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raise ValidationError(ugettext(u'This field is required.'))
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elif not self.required and not value:
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return []
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if not isinstance(value, (list, tuple)):
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raise ValidationError(ugettext(u'Enter a list of values.'))
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final_values = []
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for val in value:
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try:
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obj = self.queryset.model._default_manager.get(pk=val)
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except self.queryset.model.DoesNotExist:
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raise ValidationError(ugettext(u'Select a valid choice. %s is not one of the available choices.') % val)
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else:
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final_values.append(obj)
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return final_values
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