400 lines
16 KiB
Python
400 lines
16 KiB
Python
import copy
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import datetime
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import os
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from django.conf import settings
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from django.db.models.fields import Field
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from django.core.files.base import File, ContentFile
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from django.core.files.storage import default_storage
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from django.core.files.images import ImageFile, get_image_dimensions
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from django.core.files.uploadedfile import UploadedFile
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from django.utils.functional import curry
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from django.db.models import signals
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from django.utils.encoding import force_unicode, smart_str
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from django.utils.translation import ugettext_lazy, ugettext as _
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from django import forms
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from django.db.models.loading import cache
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class FieldFile(File):
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def __init__(self, instance, field, name):
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super(FieldFile, self).__init__(None, name)
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self.instance = instance
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self.field = field
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self.storage = field.storage
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self._committed = True
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def __eq__(self, other):
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# Older code may be expecting FileField values to be simple strings.
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# By overriding the == operator, it can remain backwards compatibility.
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if hasattr(other, 'name'):
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return self.name == other.name
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return self.name == other
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def __ne__(self, other):
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return not self.__eq__(other)
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def __hash__(self):
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# Required because we defined a custom __eq__.
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return hash(self.name)
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# The standard File contains most of the necessary properties, but
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# FieldFiles can be instantiated without a name, so that needs to
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# be checked for here.
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def _require_file(self):
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if not self:
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raise ValueError("The '%s' attribute has no file associated with it." % self.field.name)
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def _get_file(self):
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self._require_file()
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if not hasattr(self, '_file') or self._file is None:
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self._file = self.storage.open(self.name, 'rb')
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return self._file
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def _set_file(self, file):
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self._file = file
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def _del_file(self):
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del self._file
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file = property(_get_file, _set_file, _del_file)
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def _get_path(self):
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self._require_file()
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return self.storage.path(self.name)
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path = property(_get_path)
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def _get_url(self):
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self._require_file()
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return self.storage.url(self.name)
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url = property(_get_url)
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def _get_size(self):
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self._require_file()
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if not self._committed:
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return len(self.file)
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return self.storage.size(self.name)
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size = property(_get_size)
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def open(self, mode='rb'):
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self._require_file()
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self.file.open(mode)
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# open() doesn't alter the file's contents, but it does reset the pointer
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open.alters_data = True
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# In addition to the standard File API, FieldFiles have extra methods
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# to further manipulate the underlying file, as well as update the
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# associated model instance.
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def save(self, name, content, save=True):
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name = self.field.generate_filename(self.instance, name)
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self.name = self.storage.save(name, content)
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setattr(self.instance, self.field.name, self.name)
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# Update the filesize cache
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self._size = len(content)
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self._committed = True
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# Save the object because it has changed, unless save is False
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if save:
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self.instance.save()
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save.alters_data = True
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def delete(self, save=True):
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# Only close the file if it's already open, which we know by the
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# presence of self._file
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if hasattr(self, '_file'):
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self.close()
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del self.file
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self.storage.delete(self.name)
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self.name = None
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setattr(self.instance, self.field.name, self.name)
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# Delete the filesize cache
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if hasattr(self, '_size'):
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del self._size
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self._committed = False
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if save:
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self.instance.save()
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delete.alters_data = True
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def _get_closed(self):
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file = getattr(self, '_file', None)
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return file is None or file.closed
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closed = property(_get_closed)
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def close(self):
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file = getattr(self, '_file', None)
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if file is not None:
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file.close()
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def __getstate__(self):
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# FieldFile needs access to its associated model field and an instance
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# it's attached to in order to work properly, but the only necessary
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# data to be pickled is the file's name itself. Everything else will
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# be restored later, by FileDescriptor below.
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return {'name': self.name, 'closed': False, '_committed': True, '_file': None}
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class FileDescriptor(object):
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"""
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The descriptor for the file attribute on the model instance. Returns a
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FieldFile when accessed so you can do stuff like::
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>>> instance.file.size
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Assigns a file object on assignment so you can do::
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>>> instance.file = File(...)
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"""
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def __init__(self, field):
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self.field = field
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def __get__(self, instance=None, owner=None):
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if instance is None:
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raise AttributeError(
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"The '%s' attribute can only be accessed from %s instances."
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% (self.field.name, owner.__name__))
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# This is slightly complicated, so worth an explanation.
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# instance.file`needs to ultimately return some instance of `File`,
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# probably a subclass. Additionally, this returned object needs to have
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# the FieldFile API so that users can easily do things like
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# instance.file.path and have that delegated to the file storage engine.
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# Easy enough if we're strict about assignment in __set__, but if you
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# peek below you can see that we're not. So depending on the current
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# value of the field we have to dynamically construct some sort of
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# "thing" to return.
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# The instance dict contains whatever was originally assigned
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# in __set__.
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file = instance.__dict__[self.field.name]
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# If this value is a string (instance.file = "path/to/file") or None
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# then we simply wrap it with the appropriate attribute class according
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# to the file field. [This is FieldFile for FileFields and
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# ImageFieldFile for ImageFields; it's also conceivable that user
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# subclasses might also want to subclass the attribute class]. This
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# object understands how to convert a path to a file, and also how to
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# handle None.
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if isinstance(file, basestring) or file is None:
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attr = self.field.attr_class(instance, self.field, file)
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instance.__dict__[self.field.name] = attr
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# Other types of files may be assigned as well, but they need to have
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# the FieldFile interface added to the. Thus, we wrap any other type of
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# File inside a FieldFile (well, the field's attr_class, which is
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# usually FieldFile).
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elif isinstance(file, File) and not isinstance(file, FieldFile):
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file_copy = self.field.attr_class(instance, self.field, file.name)
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file_copy.file = file
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file_copy._committed = False
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instance.__dict__[self.field.name] = file_copy
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# Finally, because of the (some would say boneheaded) way pickle works,
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# the underlying FieldFile might not actually itself have an associated
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# file. So we need to reset the details of the FieldFile in those cases.
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elif isinstance(file, FieldFile) and not hasattr(file, 'field'):
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file.instance = instance
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file.field = self.field
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file.storage = self.field.storage
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# That was fun, wasn't it?
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return instance.__dict__[self.field.name]
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def __set__(self, instance, value):
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instance.__dict__[self.field.name] = value
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class FileField(Field):
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# The class to wrap instance attributes in. Accessing the file object off
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# the instance will always return an instance of attr_class.
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attr_class = FieldFile
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# The descriptor to use for accessing the attribute off of the class.
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descriptor_class = FileDescriptor
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def __init__(self, verbose_name=None, name=None, upload_to='', storage=None, **kwargs):
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for arg in ('primary_key', 'unique'):
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if arg in kwargs:
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raise TypeError("'%s' is not a valid argument for %s." % (arg, self.__class__))
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self.storage = storage or default_storage
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self.upload_to = upload_to
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if callable(upload_to):
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self.generate_filename = upload_to
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kwargs['max_length'] = kwargs.get('max_length', 100)
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super(FileField, self).__init__(verbose_name, name, **kwargs)
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def get_internal_type(self):
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return "FileField"
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def get_db_prep_lookup(self, lookup_type, value):
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if hasattr(value, 'name'):
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value = value.name
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return super(FileField, self).get_db_prep_lookup(lookup_type, value)
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def get_db_prep_value(self, value):
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"Returns field's value prepared for saving into a database."
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# Need to convert File objects provided via a form to unicode for database insertion
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if value is None:
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return None
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return unicode(value)
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def pre_save(self, model_instance, add):
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"Returns field's value just before saving."
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file = super(FileField, self).pre_save(model_instance, add)
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if file and not file._committed:
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# Commit the file to storage prior to saving the model
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file.save(file.name, file, save=False)
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return file
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def contribute_to_class(self, cls, name):
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super(FileField, self).contribute_to_class(cls, name)
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setattr(cls, self.name, self.descriptor_class(self))
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signals.post_delete.connect(self.delete_file, sender=cls)
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def delete_file(self, instance, sender, **kwargs):
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file = getattr(instance, self.attname)
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# If no other object of this type references the file,
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# and it's not the default value for future objects,
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# delete it from the backend.
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if file and file.name != self.default and \
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not sender._default_manager.filter(**{self.name: file.name}):
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file.delete(save=False)
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elif file:
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# Otherwise, just close the file, so it doesn't tie up resources.
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file.close()
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def get_directory_name(self):
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return os.path.normpath(force_unicode(datetime.datetime.now().strftime(smart_str(self.upload_to))))
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def get_filename(self, filename):
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return os.path.normpath(self.storage.get_valid_name(os.path.basename(filename)))
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def generate_filename(self, instance, filename):
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return os.path.join(self.get_directory_name(), self.get_filename(filename))
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def save_form_data(self, instance, data):
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if data:
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setattr(instance, self.name, data)
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def formfield(self, **kwargs):
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defaults = {'form_class': forms.FileField, 'max_length': self.max_length}
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# If a file has been provided previously, then the form doesn't require
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# that a new file is provided this time.
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# The code to mark the form field as not required is used by
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# form_for_instance, but can probably be removed once form_for_instance
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# is gone. ModelForm uses a different method to check for an existing file.
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if 'initial' in kwargs:
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defaults['required'] = False
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defaults.update(kwargs)
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return super(FileField, self).formfield(**defaults)
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class ImageFileDescriptor(FileDescriptor):
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"""
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Just like the FileDescriptor, but for ImageFields. The only difference is
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assigning the width/height to the width_field/height_field, if appropriate.
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"""
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def __set__(self, instance, value):
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previous_file = instance.__dict__.get(self.field.name)
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super(ImageFileDescriptor, self).__set__(instance, value)
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# To prevent recalculating image dimensions when we are instantiating
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# an object from the database (bug #11084), only update dimensions if
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# the field had a value before this assignment. Since the default
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# value for FileField subclasses is an instance of field.attr_class,
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# previous_file will only be None when we are called from
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# Model.__init__(). The ImageField.update_dimension_fields method
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# hooked up to the post_init signal handles the Model.__init__() cases.
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# Assignment happening outside of Model.__init__() will trigger the
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# update right here.
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if previous_file is not None:
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self.field.update_dimension_fields(instance, force=True)
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class ImageFieldFile(ImageFile, FieldFile):
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def delete(self, save=True):
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# Clear the image dimensions cache
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if hasattr(self, '_dimensions_cache'):
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del self._dimensions_cache
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super(ImageFieldFile, self).delete(save)
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class ImageField(FileField):
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attr_class = ImageFieldFile
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descriptor_class = ImageFileDescriptor
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def __init__(self, verbose_name=None, name=None, width_field=None, height_field=None, **kwargs):
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self.width_field, self.height_field = width_field, height_field
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FileField.__init__(self, verbose_name, name, **kwargs)
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def contribute_to_class(self, cls, name):
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super(ImageField, self).contribute_to_class(cls, name)
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# Attach update_dimension_fields so that dimension fields declared
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# after their corresponding image field don't stay cleared by
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# Model.__init__, see bug #11196.
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signals.post_init.connect(self.update_dimension_fields, sender=cls)
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def update_dimension_fields(self, instance, force=False, *args, **kwargs):
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"""
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Updates field's width and height fields, if defined.
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This method is hooked up to model's post_init signal to update
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dimensions after instantiating a model instance. However, dimensions
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won't be updated if the dimensions fields are already populated. This
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avoids unnecessary recalculation when loading an object from the
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database.
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Dimensions can be forced to update with force=True, which is how
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ImageFileDescriptor.__set__ calls this method.
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"""
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# Nothing to update if the field doesn't have have dimension fields.
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has_dimension_fields = self.width_field or self.height_field
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if not has_dimension_fields:
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return
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# getattr will call the ImageFileDescriptor's __get__ method, which
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# coerces the assigned value into an instance of self.attr_class
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# (ImageFieldFile in this case).
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file = getattr(instance, self.attname)
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# Nothing to update if we have no file and not being forced to update.
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if not file and not force:
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return
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dimension_fields_filled = not(
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(self.width_field and not getattr(instance, self.width_field))
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or (self.height_field and not getattr(instance, self.height_field))
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)
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# When both dimension fields have values, we are most likely loading
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# data from the database or updating an image field that already had
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# an image stored. In the first case, we don't want to update the
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# dimension fields because we are already getting their values from the
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# database. In the second case, we do want to update the dimensions
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# fields and will skip this return because force will be True since we
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# were called from ImageFileDescriptor.__set__.
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if dimension_fields_filled and not force:
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return
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# file should be an instance of ImageFieldFile or should be None.
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if file:
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width = file.width
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height = file.height
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else:
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# No file, so clear dimensions fields.
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width = None
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height = None
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# Update the width and height fields.
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if self.width_field:
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setattr(instance, self.width_field, width)
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if self.height_field:
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setattr(instance, self.height_field, height)
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def formfield(self, **kwargs):
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defaults = {'form_class': forms.ImageField}
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defaults.update(kwargs)
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return super(ImageField, self).formfield(**defaults)
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