File storage refactoring, adding far more flexibility to Django's file handling. The new files.txt document has details of the new features.

This is a backwards-incompatible change; consult BackwardsIncompatibleChanges for details.

Fixes #3567, #3621, #4345, #5361, #5655, #7415.

Many thanks to Marty Alchin who did the vast majority of this work.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@8244 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/models/fields/files.py

@@ -0,0 +1,315 @@
+import datetime
+import os
+
+from django.conf import settings
+from django.db.models.fields import Field
+from django.core.files.base import File, ContentFile
+from django.core.files.storage import default_storage
+from django.core.files.images import ImageFile, get_image_dimensions
+from django.core.files.uploadedfile import UploadedFile
+from django.utils.functional import curry
+from django.db.models import signals
+from django.utils.encoding import force_unicode, smart_str
+from django.utils.translation import ugettext_lazy, ugettext as _
+from django import oldforms
+from django import forms
+from django.core import validators
+from django.db.models.loading import cache
+
+class FieldFile(File):
+    def __init__(self, instance, field, name):
+        self.instance = instance
+        self.field = field
+        self.storage = field.storage
+        self._name = name or u''
+        self._closed = False
+
+    def __eq__(self, other):
+        # Older code may be expecting FileField values to be simple strings.
+        # By overriding the == operator, it can remain backwards compatibility.
+        if hasattr(other, 'name'):
+            return self.name == other.name
+        return self.name == other
+
+    # The standard File contains most of the necessary properties, but
+    # FieldFiles can be instantiated without a name, so that needs to
+    # be checked for here.
+
+    def _require_file(self):
+        if not self:
+            raise ValueError("The '%s' attribute has no file associated with it." % self.field.name)
+
+    def _get_file(self):
+        self._require_file()
+        if not hasattr(self, '_file'):
+            self._file = self.storage.open(self.name, 'rb')
+        return self._file
+    file = property(_get_file)
+
+    def _get_path(self):
+        self._require_file()
+        return self.storage.path(self.name)
+    path = property(_get_path)
+
+    def _get_url(self):
+        self._require_file()
+        return self.storage.url(self.name)
+    url = property(_get_url)
+
+    def open(self, mode='rb'):
+        self._require_file()
+        return super(FieldFile, self).open(mode)
+    # open() doesn't alter the file's contents, but it does reset the pointer
+    open.alters_data = True
+
+    # In addition to the standard File API, FieldFiles have extra methods
+    # to further manipulate the underlying file, as well as update the
+    # associated model instance.
+
+    def save(self, name, content, save=True):
+        name = self.field.generate_filename(self.instance, name)
+        self._name = self.storage.save(name, content)
+        setattr(self.instance, self.field.name, self.name)
+
+        # Update the filesize cache
+        self._size = len(content)
+
+        # Save the object because it has changed, unless save is False
+        if save:
+            self.instance.save()
+    save.alters_data = True
+
+    def delete(self, save=True):
+        self.close()
+        self.storage.delete(self.name)
+
+        self._name = None
+        setattr(self.instance, self.field.name, self.name)
+
+        # Delete the filesize cache
+        if hasattr(self, '_size'):
+            del self._size
+
+        if save:
+            self.instance.save()
+    delete.alters_data = True
+
+    def __getstate__(self):
+        # FieldFile needs access to its associated model field and an instance
+        # it's attached to in order to work properly, but the only necessary
+        # data to be pickled is the file's name itself. Everything else will
+        # be restored later, by FileDescriptor below.
+        return {'_name': self.name, '_closed': False}
+
+class FileDescriptor(object):
+    def __init__(self, field):
+        self.field = field
+
+    def __get__(self, instance=None, owner=None):
+        if instance is None:
+            raise AttributeError, "%s can only be accessed from %s instances." % (self.field.name(self.owner.__name__))
+        file = instance.__dict__[self.field.name]
+        if not isinstance(file, FieldFile):
+            # Create a new instance of FieldFile, based on a given file name
+            instance.__dict__[self.field.name] = self.field.attr_class(instance, self.field, file)
+        elif not hasattr(file, 'field'):
+            # The FieldFile was pickled, so some attributes need to be reset.
+            file.instance = instance
+            file.field = self.field
+            file.storage = self.field.storage
+        return instance.__dict__[self.field.name]
+
+    def __set__(self, instance, value):
+        instance.__dict__[self.field.name] = value
+
+class FileField(Field):
+    attr_class = FieldFile
+
+    def __init__(self, verbose_name=None, name=None, upload_to='', storage=None, **kwargs):
+        for arg in ('core', 'primary_key', 'unique'):
+            if arg in kwargs:
+                raise TypeError("'%s' is not a valid argument for %s." % (arg, self.__class__))
+
+        self.storage = storage or default_storage
+        self.upload_to = upload_to
+        if callable(upload_to):
+            self.generate_filename = upload_to
+
+        kwargs['max_length'] = kwargs.get('max_length', 100)
+        super(FileField, self).__init__(verbose_name, name, **kwargs)
+
+    def get_internal_type(self):
+        return "FileField"
+
+    def get_db_prep_lookup(self, lookup_type, value):
+        if hasattr(value, 'name'):
+            value = value.name
+        return super(FileField, self).get_db_prep_lookup(lookup_type, value)
+
+    def get_db_prep_value(self, value):
+        "Returns field's value prepared for saving into a database."
+        # Need to convert File objects provided via a form to unicode for database insertion
+        if value is None:
+            return None
+        return unicode(value)
+
+    def get_manipulator_fields(self, opts, manipulator, change, name_prefix='', rel=False, follow=True):
+        field_list = Field.get_manipulator_fields(self, opts, manipulator, change, name_prefix, rel, follow)
+        if not self.blank:
+            if rel:
+                # This validator makes sure FileFields work in a related context.
+                class RequiredFileField(object):
+                    def __init__(self, other_field_names, other_file_field_name):
+                        self.other_field_names = other_field_names
+                        self.other_file_field_name = other_file_field_name
+                        self.always_test = True
+                    def __call__(self, field_data, all_data):
+                        if not all_data.get(self.other_file_field_name, False):
+                            c = validators.RequiredIfOtherFieldsGiven(self.other_field_names, ugettext_lazy("This field is required."))
+                            c(field_data, all_data)
+                # First, get the core fields, if any.
+                core_field_names = []
+                for f in opts.fields:
+                    if f.core and f != self:
+                        core_field_names.extend(f.get_manipulator_field_names(name_prefix))
+                # Now, if there are any, add the validator to this FormField.
+                if core_field_names:
+                    field_list[0].validator_list.append(RequiredFileField(core_field_names, field_list[1].field_name))
+            else:
+                v = validators.RequiredIfOtherFieldNotGiven(field_list[1].field_name, ugettext_lazy("This field is required."))
+                v.always_test = True
+                field_list[0].validator_list.append(v)
+                field_list[0].is_required = field_list[1].is_required = False
+
+        # If the raw path is passed in, validate it's under the MEDIA_ROOT.
+        def isWithinMediaRoot(field_data, all_data):
+            f = os.path.abspath(os.path.join(settings.MEDIA_ROOT, field_data))
+            if not f.startswith(os.path.abspath(os.path.normpath(settings.MEDIA_ROOT))):
+                raise validators.ValidationError(_("Enter a valid filename."))
+        field_list[1].validator_list.append(isWithinMediaRoot)
+        return field_list
+
+    def contribute_to_class(self, cls, name):
+        super(FileField, self).contribute_to_class(cls, name)
+        setattr(cls, self.name, FileDescriptor(self))
+        setattr(cls, 'get_%s_filename' % self.name, curry(cls._get_FIELD_filename, field=self))
+        setattr(cls, 'get_%s_url' % self.name, curry(cls._get_FIELD_url, field=self))
+        setattr(cls, 'get_%s_size' % self.name, curry(cls._get_FIELD_size, field=self))
+        setattr(cls, 'save_%s_file' % self.name, lambda instance, name, content, save=True: instance._save_FIELD_file(self, name, content, save))
+        signals.post_delete.connect(self.delete_file, sender=cls)
+
+    def delete_file(self, instance, sender, **kwargs):
+        file = getattr(instance, self.attname)
+        # If no other object of this type references the file,
+        # and it's not the default value for future objects,
+        # delete it from the backend.
+        if file and file.name != self.default and \
+            not sender._default_manager.filter(**{self.name: file.name}):
+                file.delete(save=False)
+        elif file:
+            # Otherwise, just close the file, so it doesn't tie up resources.
+            file.close()
+
+    def get_manipulator_field_objs(self):
+        return [oldforms.FileUploadField, oldforms.HiddenField]
+
+    def get_manipulator_field_names(self, name_prefix):
+        return [name_prefix + self.name + '_file', name_prefix + self.name]
+
+    def save_file(self, new_data, new_object, original_object, change, rel, save=True):
+        upload_field_name = self.get_manipulator_field_names('')[0]
+        if new_data.get(upload_field_name, False):
+            if rel:
+                file = new_data[upload_field_name][0]
+            else:
+                file = new_data[upload_field_name]
+
+            # Backwards-compatible support for files-as-dictionaries.
+            # We don't need to raise a warning because the storage backend will
+            # do so for us.
+            try:
+                filename = file.name
+            except AttributeError:
+                filename = file['filename']
+            filename = self.get_filename(filename)
+
+            getattr(new_object, self.attname).save(filename, file, save)
+
+    def get_directory_name(self):
+        return os.path.normpath(force_unicode(datetime.datetime.now().strftime(smart_str(self.upload_to))))
+
+    def get_filename(self, filename):
+        return os.path.normpath(self.storage.get_valid_name(os.path.basename(filename)))
+
+    def generate_filename(self, instance, filename):
+        return os.path.join(self.get_directory_name(), self.get_filename(filename))
+
+    def save_form_data(self, instance, data):
+        if data and isinstance(data, UploadedFile):
+            getattr(instance, self.name).save(data.name, data, save=False)
+
+    def formfield(self, **kwargs):
+        defaults = {'form_class': forms.FileField}
+        # If a file has been provided previously, then the form doesn't require
+        # that a new file is provided this time.
+        # The code to mark the form field as not required is used by
+        # form_for_instance, but can probably be removed once form_for_instance
+        # is gone. ModelForm uses a different method to check for an existing file.
+        if 'initial' in kwargs:
+            defaults['required'] = False
+        defaults.update(kwargs)
+        return super(FileField, self).formfield(**defaults)
+
+class ImageFieldFile(ImageFile, FieldFile):
+    def save(self, name, content, save=True):
+
+        if not hasattr(content, 'read'):
+            import warnings
+            warnings.warn(
+                message = "Representing files as strings is deprecated." \
+                          "Use django.core.files.base.ContentFile instead.",
+                category = DeprecationWarning,
+                stacklevel = 2
+            )
+            content = ContentFile(content)
+
+        # Repopulate the image dimension cache.
+        self._dimensions_cache = get_image_dimensions(content)
+        
+        # Update width/height fields, if needed
+        if self.field.width_field:
+            setattr(self.instance, self.field.width_field, self.width)
+        if self.field.height_field:
+            setattr(self.instance, self.field.height_field, self.height)
+        
+        super(ImageFieldFile, self).save(name, content, save)
+
+    def delete(self, save=True):
+        # Clear the image dimensions cache
+        if hasattr(self, '_dimensions_cache'):
+            del self._dimensions_cache
+        super(ImageFieldFile, self).delete(save)
+
+class ImageField(FileField):
+    attr_class = ImageFieldFile
+
+    def __init__(self, verbose_name=None, name=None, width_field=None, height_field=None, **kwargs):
+        self.width_field, self.height_field = width_field, height_field
+        FileField.__init__(self, verbose_name, name, **kwargs)
+
+    def get_manipulator_field_objs(self):
+        return [oldforms.ImageUploadField, oldforms.HiddenField]
+
+    def contribute_to_class(self, cls, name):
+        super(ImageField, self).contribute_to_class(cls, name)
+        # Add get_BLAH_width and get_BLAH_height methods, but only if the
+        # image field doesn't have width and height cache fields.
+        if not self.width_field:
+            setattr(cls, 'get_%s_width' % self.name, curry(cls._get_FIELD_width, field=self))
+        if not self.height_field:
+            setattr(cls, 'get_%s_height' % self.name, curry(cls._get_FIELD_height, field=self))
+
+    def formfield(self, **kwargs):
+        defaults = {'form_class': forms.ImageField}
+        defaults.update(kwargs)
+        return super(ImageField, self).formfield(**defaults)