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Fixed #31701 -- Made FileDescriptor subclass DeferredAttribute.

This commit is contained in:
alosultan 2020-06-12 15:58:53 +03:00 committed by Mariusz Felisiak
parent dd5aa8cb5f
commit a93425a37f
1 changed files with 8 additions and 16 deletions
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24
django/db/models/fields/files.py
View File

@ -8,6 +8,7 @@ from django.core.files.images import ImageFile
from django.core.files.storage import Storage, default_storage from django.core.files.storage import Storage, default_storage
from django.db.models import signals from django.db.models import signals
from django.db.models.fields import Field from django.db.models.fields import Field
from django.db.models.query_utils import DeferredAttribute
from django.utils.translation import gettext_lazy as _ from django.utils.translation import gettext_lazy as _
@ -140,7 +141,7 @@ class FieldFile(File):
self.storage = self.field.storage self.storage = self.field.storage
class FileDescriptor: class FileDescriptor(DeferredAttribute):
""" """
The descriptor for the file attribute on the model instance. Return a The descriptor for the file attribute on the model instance. Return a
FieldFile when accessed so you can write code like:: FieldFile when accessed so you can write code like::
@ -154,9 +155,6 @@ class FileDescriptor:
>>> with open('/path/to/hello.world') as f: >>> with open('/path/to/hello.world') as f:
... instance.file = File(f) ... instance.file = File(f)
""" """
def __init__(self, field):
self.field = field
def __get__(self, instance, cls=None): def __get__(self, instance, cls=None):
if instance is None: if instance is None:
return self return self
@ -173,9 +171,7 @@ class FileDescriptor:
# The instance dict contains whatever was originally assigned # The instance dict contains whatever was originally assigned
# in __set__. # in __set__.
if self.field.name not in instance.__dict__: file = super().__get__(instance, cls)
instance.refresh_from_db(fields=[self.field.name])
file = instance.__dict__[self.field.name]
# If this value is a string (instance.file = "path/to/file") or None # If this value is a string (instance.file = "path/to/file") or None
# then we simply wrap it with the appropriate attribute class according # then we simply wrap it with the appropriate attribute class according
@ -186,7 +182,7 @@ class FileDescriptor:
# handle None. # handle None.
if isinstance(file, str) or file is None: if isinstance(file, str) or file is None:
attr = self.field.attr_class(instance, self.field, file) attr = self.field.attr_class(instance, self.field, file)
instance.__dict__[self.field.name] = attr instance.__dict__[self.field.attname] = attr
# Other types of files may be assigned as well, but they need to have # Other types of files may be assigned as well, but they need to have
# the FieldFile interface added to them. Thus, we wrap any other type of # the FieldFile interface added to them. Thus, we wrap any other type of
@ -196,7 +192,7 @@ class FileDescriptor:
file_copy = self.field.attr_class(instance, self.field, file.name) file_copy = self.field.attr_class(instance, self.field, file.name)
file_copy.file = file file_copy.file = file
file_copy._committed = False file_copy._committed = False
instance.__dict__[self.field.name] = file_copy instance.__dict__[self.field.attname] = file_copy
# Finally, because of the (some would say boneheaded) way pickle works, # Finally, because of the (some would say boneheaded) way pickle works,
# the underlying FieldFile might not actually itself have an associated # the underlying FieldFile might not actually itself have an associated
@ -211,10 +207,10 @@ class FileDescriptor:
file.instance = instance file.instance = instance
# That was fun, wasn't it? # That was fun, wasn't it?
return instance.__dict__[self.field.name] return instance.__dict__[self.field.attname]
def __set__(self, instance, value): def __set__(self, instance, value):
instance.__dict__[self.field.name] = value instance.__dict__[self.field.attname] = value
class FileField(Field): class FileField(Field):
@ -303,10 +299,6 @@ class FileField(Field):
file.save(file.name, file.file, save=False) file.save(file.name, file.file, save=False)
return file return file
def contribute_to_class(self, cls, name, **kwargs):
super().contribute_to_class(cls, name, **kwargs)
setattr(cls, self.name, self.descriptor_class(self))
def generate_filename(self, instance, filename): def generate_filename(self, instance, filename):
""" """
Apply (if callable) or prepend (if a string) upload_to to the filename, Apply (if callable) or prepend (if a string) upload_to to the filename,
@ -345,7 +337,7 @@ class ImageFileDescriptor(FileDescriptor):
assigning the width/height to the width_field/height_field, if appropriate. assigning the width/height to the width_field/height_field, if appropriate.
""" """
def __set__(self, instance, value): def __set__(self, instance, value):
previous_file = instance.__dict__.get(self.field.name) previous_file = instance.__dict__.get(self.field.attname)
super().__set__(instance, value) super().__set__(instance, value)
# To prevent recalculating image dimensions when we are instantiating # To prevent recalculating image dimensions when we are instantiating