99 lines
4.1 KiB
Python
99 lines
4.1 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 forms import BaseForm, DeclarativeFieldsMetaclass, SortedDictFromList
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__all__ = ('save_instance', 'form_for_model', 'form_for_instance', 'form_for_fields')
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def model_save(self, commit=True):
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"""
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Creates and returns model instance according to self.clean_data.
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This method is created for any form_for_model Form.
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"""
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if self.errors:
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raise ValueError("The %s could not be created because the data didn't validate." % self._model._meta.object_name)
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return save_instance(self, self._model(), commit)
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def save_instance(form, instance, commit=True):
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"""
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Saves bound Form ``form``'s clean_data into model instance ``instance``.
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Assumes ``form`` has a field for every non-AutoField database field in
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``instance``. If commit=True, then the changes to ``instance`` will be
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saved to the 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 changed because the data didn't validate." % opts.object_name)
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clean_data = form.clean_data
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for f in opts.fields:
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if isinstance(f, models.AutoField):
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continue
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setattr(instance, f.attname, clean_data[f.name])
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if commit:
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instance.save()
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for f in opts.many_to_many:
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setattr(instance, f.attname, getattr(instance, f.attname).model.objects.filter(pk__in = clean_data[f.name]))
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# GOTCHA: If many-to-many data is given and commit=False, the many-to-many
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# data will be lost. This happens because a many-to-many options cannot be
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# set on an object until after it's saved. Maybe we should raise an
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# exception in that case.
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return instance
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def make_instance_save(instance):
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"Returns the save() method for a form_for_instance Form."
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def save(self, commit=True):
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return save_instance(self, instance, commit)
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return save
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def form_for_model(model, form=BaseForm, 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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formfield = formfield_callback(f)
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if formfield:
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field_list.append((f.name, formfield))
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fields = SortedDictFromList(field_list)
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return type(opts.object_name + 'Form', (form,), {'base_fields': fields, '_model': model, 'save': model_save})
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def form_for_instance(instance, form=BaseForm, 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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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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fields = SortedDictFromList(field_list)
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return type(opts.object_name + 'InstanceForm', (form,),
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{'base_fields': fields, '_model': model, 'save': make_instance_save(instance)})
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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])
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return type('FormForFields', (BaseForm,), {'base_fields': fields})
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