Fixes #28184 - Add ability to pass a callable as the storage param to…

… FileField, and add test

Signed-off-by: miigotu <miigotu@gmail.com>

django/db/models/fields/files.py

@@ -225,6 +225,10 @@ def __init__(self, verbose_name=None, name=None, upload_to='', storage=None, **k
         self._primary_key_set_explicitly = 'primary_key' in kwargs
 
         self.storage = storage or default_storage
+
+        if callable(self.storage):
+            self.storage = self.storage()
+
         self.upload_to = upload_to
 
         kwargs['max_length'] = kwargs.get('max_length', 100)

tests/file_storage/models.py

@@ -20,6 +20,15 @@ def get_valid_name(self, name):
 
 temp_storage_location = tempfile.mkdtemp()
 temp_storage = FileSystemStorage(location=temp_storage_location)
+temp_valid_name_storage = CustomValidNameStorage(location=temp_storage_location)
+
+use_valid_name_storage = False
+
+
+def callable_temp_storage():
+    if use_valid_name_storage:
+        return temp_valid_name_storage
+    return temp_storage
 
 
 class Storage(models.Model):
@@ -35,9 +44,13 @@ def random_upload_to(self, filename):
     custom = models.FileField(storage=temp_storage, upload_to=custom_upload_to)
     random = models.FileField(storage=temp_storage, upload_to=random_upload_to)
     custom_valid_name = models.FileField(
-        storage=CustomValidNameStorage(location=temp_storage_location),
+        storage=temp_valid_name_storage,
         upload_to=random_upload_to,
     )
+    callable_storage = models.FileField(
+        storage=callable_temp_storage,
+        upload_to=custom_upload_to,
+    )
     default = models.FileField(storage=temp_storage, upload_to='tests', default='tests/default.txt')
     empty = models.FileField(storage=temp_storage)
     limited_length = models.FileField(storage=temp_storage, upload_to='tests', max_length=20)

tests/file_storage/tests.py

@@ -24,7 +24,11 @@
 from django.urls import NoReverseMatch, reverse_lazy
 from django.utils import timezone
 
-from .models import Storage, temp_storage, temp_storage_location
+from . import models
+from .models import (
+    Storage, temp_storage, temp_storage_location, temp_valid_name_storage,
+)
+
 
 FILE_SUFFIX_REGEX = '[A-Za-z0-9]{7}'
 
@@ -801,6 +805,15 @@ def test_stringio(self):
         with temp_storage.open('tests/stringio') as f:
             self.assertEqual(f.read(), b'content')
 
+    def test_callable_storage_param(self):
+        models.use_valid_name_storage = False
+        obj1 = Storage.objects.create()
+        self.assertIs(obj1.callable_storage.storage, temp_storage)
+
+        models.use_valid_name_storage = True
+        obj2 = Storage.objects.create()
+        self.assertIs(obj2.callable_storage.storage, temp_valid_name_storage)
+
 
 # Tests for a race condition on file saving (#4948).
 # This is written in such a way that it'll always pass on platforms