Fixed #35384 -- raised FieldError when trying to save ContentFile ins…

…tance to File field

django/core/files/base.py

@@ -1,7 +1,7 @@
 import os
 from io import BytesIO, StringIO, UnsupportedOperation
 
-from django.core.files.utils import FileProxyMixin
+from django.core.files.utils import EmptyName, FileProxyMixin
 from django.utils.functional import cached_property
 
 
@@ -124,6 +124,8 @@ class ContentFile(File):
     """
 
     def __init__(self, content, name=None):
+        if name is None:
+            name = EmptyName()
         stream_class = StringIO if isinstance(content, str) else BytesIO
         super().__init__(stream_class(content), name=name)
         self.size = len(content)

django/core/files/utils.py

@@ -4,6 +4,10 @@
 from django.core.exceptions import SuspiciousFileOperation
 
 
+class EmptyName:
+    pass
+
+
 def validate_file_name(name, allow_relative_path=False):
     # Remove potentially dangerous names
     if os.path.basename(name) in {"", ".", ".."}:

django/db/models/fields/files.py

@@ -3,10 +3,11 @@
 
 from django import forms
 from django.core import checks
+from django.core.exceptions import FieldError
 from django.core.files.base import File
 from django.core.files.images import ImageFile
 from django.core.files.storage import Storage, default_storage
-from django.core.files.utils import validate_file_name
+from django.core.files.utils import EmptyName, validate_file_name
 from django.db.models import signals
 from django.db.models.fields import Field
 from django.db.models.query_utils import DeferredAttribute
@@ -312,6 +313,8 @@ def get_prep_value(self, value):
 
     def pre_save(self, model_instance, add):
         file = super().pre_save(model_instance, add)
+        if isinstance(file.name, EmptyName):
+            raise FieldError("File name cannot be empty.")
         if file and not file._committed:
             # Commit the file to storage prior to saving the model
             file.save(file.name, file.file, save=False)

tests/files/tests.py

@@ -18,6 +18,7 @@
     TemporaryUploadedFile,
     UploadedFile,
 )
+from django.core.files.utils import EmptyName
 from django.test import override_settings
 
 try:
@@ -236,7 +237,7 @@ def test_noname_file_get_size(self):
 
 class ContentFileTestCase(unittest.TestCase):
     def test_content_file_default_name(self):
-        self.assertIsNone(ContentFile(b"content").name)
+        self.assertTrue(isinstance(ContentFile(b"content").name, EmptyName))
 
     def test_content_file_custom_name(self):
         """

tests/model_fields/test_filefield.py

@@ -5,7 +5,7 @@
 import unittest
 from pathlib import Path
 
-from django.core.exceptions import SuspiciousFileOperation
+from django.core.exceptions import FieldError, SuspiciousFileOperation
 from django.core.files import File, temp
 from django.core.files.base import ContentFile
 from django.core.files.uploadedfile import TemporaryUploadedFile
@@ -72,6 +72,13 @@ def test_save_without_name(self):
             with self.assertRaisesMessage(SuspiciousFileOperation, msg):
                 document.save()
 
+    def test_save_content_file_without_name(self):
+        d = Document()
+        d.myfile = ContentFile(b"")
+        msg = "File name cannot be empty."
+        with self.assertRaisesMessage(FieldError, msg):
+            d.save()
+
     def test_defer(self):
         Document.objects.create(myfile="something.txt")
         self.assertEqual(Document.objects.defer("myfile")[0].myfile, "something.txt")