import datetime
import os
import django.utils.copycompat as copy
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
from django import forms
from django.db.models.loading import cache
class FieldFile(File):
def __init__(self, instance, field, name):
super(FieldFile, self).__init__(None, name)
self.instance = instance
self.field = field
self.storage = field.storage
self._committed = True
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
def __ne__(self, other):
return not self.__eq__(other)
def __hash__(self):
# Required because we defined a custom __eq__.
return hash(self.name)
# 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') or self._file is None:
self._file = self.storage.open(self.name, 'rb')
return self._file
def _set_file(self, file):
self._file = file
def _del_file(self):
del self._file
file = property(_get_file, _set_file, _del_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 _get_size(self):
self._require_file()
if not self._committed:
return len(self.file)
return self.storage.size(self.name)
size = property(_get_size)
def open(self, mode='rb'):
self._require_file()
self.file.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)
self._committed = True
# 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):
# Only close the file if it's already open, which we know by the
# presence of self._file
if hasattr(self, '_file'):
self.close()
del self.file
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
self._committed = False
if save:
self.instance.save()
delete.alters_data = True
def _get_closed(self):
file = getattr(self, '_file', None)
return file is None or file.closed
closed = property(_get_closed)
def close(self):
file = getattr(self, '_file', None)
if file is not None:
file.close()
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, '_committed': True, '_file': None}
class FileDescriptor(object):
"""
The descriptor for the file attribute on the model instance. Returns a
FieldFile when accessed so you can do stuff like::
>>> instance.file.size
Assigns a file object on assignment so you can do::
>>> instance.file = File(...)
"""
def __init__(self, field):
self.field = field
def __get__(self, instance=None, owner=None):
if instance is None:
raise AttributeError(
"The '%s' attribute can only be accessed from %s instances."
% (self.field.name, owner.__name__))
# This is slightly complicated, so worth an explanation.
# instance.file`needs to ultimately return some instance of `File`,
# probably a subclass. Additionally, this returned object needs to have
# the FieldFile API so that users can easily do things like
# instance.file.path and have that delegated to the file storage engine.
# Easy enough if we're strict about assignment in __set__, but if you
# peek below you can see that we're not. So depending on the current
# value of the field we have to dynamically construct some sort of
# "thing" to return.
# The instance dict contains whatever was originally assigned
# in __set__.
file = instance.__dict__[self.field.name]
# If this value is a string (instance.file = "path/to/file") or None
# then we simply wrap it with the appropriate attribute class according
# to the file field. [This is FieldFile for FileFields and
# ImageFieldFile for ImageFields; it's also conceivable that user
# subclasses might also want to subclass the attribute class]. This
# object understands how to convert a path to a file, and also how to
# handle None.
if isinstance(file, basestring) or file is None:
attr = self.field.attr_class(instance, self.field, file)
instance.__dict__[self.field.name] = attr
# Other types of files may be assigned as well, but they need to have
# the FieldFile interface added to the. Thus, we wrap any other type of
# File inside a FieldFile (well, the field's attr_class, which is
# usually FieldFile).
elif isinstance(file, File) and not isinstance(file, FieldFile):
file_copy = self.field.attr_class(instance, self.field, file.name)
file_copy.file = file
file_copy._committed = False
instance.__dict__[self.field.name] = file_copy
# Finally, because of the (some would say boneheaded) way pickle works,
# the underlying FieldFile might not actually itself have an associated
# file. So we need to reset the details of the FieldFile in those cases.
elif isinstance(file, FieldFile) and not hasattr(file, 'field'):
file.instance = instance
file.field = self.field
file.storage = self.field.storage
# That was fun, wasn't it?
return instance.__dict__[self.field.name]
def __set__(self, instance, value):
instance.__dict__[self.field.name] = value
class FileField(Field):
# The class to wrap instance attributes in. Accessing the file object off
# the instance will always return an instance of attr_class.
attr_class = FieldFile
# The descriptor to use for accessing the attribute off of the class.
descriptor_class = FileDescriptor
description = ugettext_lazy("File path")
def __init__(self, verbose_name=None, name=None, upload_to='', storage=None, **kwargs):
for arg in ('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_prep_lookup(self, lookup_type, value):
if hasattr(value, 'name'):
value = value.name
return super(FileField, self).get_prep_lookup(lookup_type, value)
def get_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 pre_save(self, model_instance, add):
"Returns field's value just before saving."
file = super(FileField, self).pre_save(model_instance, add)
if file and not file._committed:
# Commit the file to storage prior to saving the model
file.save(file.name, file, save=False)
return file
def contribute_to_class(self, cls, name):
super(FileField, self).contribute_to_class(cls, name)
setattr(cls, self.name, self.descriptor_class(self))
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_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:
setattr(instance, self.name, data)
def formfield(self, **kwargs):
defaults = {'form_class': forms.FileField, 'max_length': self.max_length}
# 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 ImageFileDescriptor(FileDescriptor):
"""
Just like the FileDescriptor, but for ImageFields. The only difference is
assigning the width/height to the width_field/height_field, if appropriate.
"""
def __set__(self, instance, value):
previous_file = instance.__dict__.get(self.field.name)
super(ImageFileDescriptor, self).__set__(instance, value)
# To prevent recalculating image dimensions when we are instantiating
# an object from the database (bug #11084), only update dimensions if
# the field had a value before this assignment. Since the default
# value for FileField subclasses is an instance of field.attr_class,
# previous_file will only be None when we are called from
# Model.__init__(). The ImageField.update_dimension_fields method
# hooked up to the post_init signal handles the Model.__init__() cases.
# Assignment happening outside of Model.__init__() will trigger the
# update right here.
if previous_file is not None:
self.field.update_dimension_fields(instance, force=True)
class ImageFieldFile(ImageFile, FieldFile):
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
descriptor_class = ImageFileDescriptor
description = ugettext_lazy("File path")
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 contribute_to_class(self, cls, name):
super(ImageField, self).contribute_to_class(cls, name)
# Attach update_dimension_fields so that dimension fields declared
# after their corresponding image field don't stay cleared by
# Model.__init__, see bug #11196.
signals.post_init.connect(self.update_dimension_fields, sender=cls)
def update_dimension_fields(self, instance, force=False, *args, **kwargs):
"""
Updates field's width and height fields, if defined.
This method is hooked up to model's post_init signal to update
dimensions after instantiating a model instance. However, dimensions
won't be updated if the dimensions fields are already populated. This
avoids unnecessary recalculation when loading an object from the
database.
Dimensions can be forced to update with force=True, which is how
ImageFileDescriptor.__set__ calls this method.
"""
# Nothing to update if the field doesn't have have dimension fields.
has_dimension_fields = self.width_field or self.height_field
if not has_dimension_fields:
return
# getattr will call the ImageFileDescriptor's __get__ method, which
# coerces the assigned value into an instance of self.attr_class
# (ImageFieldFile in this case).
file = getattr(instance, self.attname)
# Nothing to update if we have no file and not being forced to update.
if not file and not force:
return
dimension_fields_filled = not(
(self.width_field and not getattr(instance, self.width_field))
or (self.height_field and not getattr(instance, self.height_field))
)
# When both dimension fields have values, we are most likely loading
# data from the database or updating an image field that already had
# an image stored. In the first case, we don't want to update the
# dimension fields because we are already getting their values from the
# database. In the second case, we do want to update the dimensions
# fields and will skip this return because force will be True since we
# were called from ImageFileDescriptor.__set__.
if dimension_fields_filled and not force:
return
# file should be an instance of ImageFieldFile or should be None.
if file:
width = file.width
height = file.height
else:
# No file, so clear dimensions fields.
width = None
height = None
# Update the width and height fields.
if self.width_field:
setattr(instance, self.width_field, width)
if self.height_field:
setattr(instance, self.height_field, height)
def formfield(self, **kwargs):
defaults = {'form_class': forms.ImageField}
defaults.update(kwargs)
return super(ImageField, self).formfield(**defaults)
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