Fixed #27188 -- Allowed using unique=True with FileField.

Thanks Tim Graham for the initial patch.

django/db/models/fields/files.py

@@ -230,7 +230,6 @@ class FileField(Field):
 
     def __init__(self, verbose_name=None, name=None, upload_to='', storage=None, **kwargs):
         self._primary_key_set_explicitly = 'primary_key' in kwargs
-        self._unique_set_explicitly = 'unique' in kwargs
 
         self.storage = storage or default_storage
         self.upload_to = upload_to
@@ -240,22 +239,9 @@ class FileField(Field):
 
     def check(self, **kwargs):
         errors = super(FileField, self).check(**kwargs)
-        errors.extend(self._check_unique())
         errors.extend(self._check_primary_key())
         return errors
 
-    def _check_unique(self):
-        if self._unique_set_explicitly:
-            return [
-                checks.Error(
-                    "'unique' is not a valid argument for a %s." % self.__class__.__name__,
-                    obj=self,
-                    id='fields.E200',
-                )
-            ]
-        else:
-            return []
-
     def _check_primary_key(self):
         if self._primary_key_set_explicitly:
             return [

docs/ref/checks.txt

@@ -183,6 +183,7 @@ File Fields
 ~~~~~~~~~~~
 
 * **fields.E200**: ``unique`` is not a valid argument for a ``FileField``.
+  *This check is removed in Django 1.11*.
 * **fields.E201**: ``primary_key`` is not a valid argument for a ``FileField``.
 * **fields.E210**: Cannot use ``ImageField`` because Pillow is not installed.
 

docs/ref/models/fields.txt

@@ -306,12 +306,16 @@ you try to save a model with a duplicate value in a :attr:`~Field.unique`
 field, a :exc:`django.db.IntegrityError` will be raised by the model's
 :meth:`~django.db.models.Model.save` method.
 
-This option is valid on all field types except :class:`ManyToManyField`,
+This option is valid on all field types except :class:`ManyToManyField` and
-:class:`OneToOneField`, and :class:`FileField`.
+:class:`OneToOneField`.
 
 Note that when ``unique`` is ``True``, you don't need to specify
 :attr:`~Field.db_index`, because ``unique`` implies the creation of an index.
 
+.. versionchanged:: 1.11
+
+    In older versions, ``unique=True`` can't be used on :class:`FileField`.
+
 ``unique_for_date``
 -------------------
 
@@ -628,8 +632,8 @@ uses :class:`~django.core.validators.EmailValidator` to validate the input.
 A file-upload field.
 
 .. note::
-    The ``primary_key`` and ``unique`` arguments are not supported, and will
+    The ``primary_key`` argument isn't supported and will raise a an error if
-    raise a ``TypeError`` if used.
+    used.
 
 Has two optional arguments:
 

docs/releases/1.11.txt

@@ -312,6 +312,9 @@ Models
 * Added support for query expressions on lookups that take multiple arguments,
   such as ``range``.
 
+* You can now use the ``unique=True`` option with
+  :class:`~django.db.models.FileField`.
+
 Requests and Responses
 ~~~~~~~~~~~~~~~~~~~~~~
 

tests/invalid_models_tests/test_ordinary_fields.py

@@ -440,21 +440,6 @@ class FileFieldTests(SimpleTestCase):
         expected = []
         self.assertEqual(errors, expected)
 
-    def test_unique(self):
-        class Model(models.Model):
-            field = models.FileField(unique=False, upload_to='somewhere')
-
-        field = Model._meta.get_field('field')
-        errors = field.check()
-        expected = [
-            Error(
-                "'unique' is not a valid argument for a FileField.",
-                obj=field,
-                id='fields.E200',
-            )
-        ]
-        self.assertEqual(errors, expected)
-
     def test_primary_key(self):
         class Model(models.Model):
             field = models.FileField(primary_key=False, upload_to='somewhere')

tests/model_fields/models.py

@@ -216,7 +216,7 @@ class DataModel(models.Model):
 
 
 class Document(models.Model):
-    myfile = models.FileField(upload_to='unused')
+    myfile = models.FileField(upload_to='unused', unique=True)
 
 ###############################################################################
 # ImageField

tests/model_fields/test_filefield.py

@@ -4,6 +4,7 @@ import unittest
 
 from django.core.files import temp
 from django.core.files.uploadedfile import TemporaryUploadedFile
+from django.db.utils import IntegrityError
 from django.test import TestCase, override_settings
 
 from .models import Document
@@ -61,6 +62,15 @@ class FileFieldTests(TestCase):
         Document.objects.create(myfile='something.txt')
         self.assertEqual(Document.objects.defer('myfile')[0].myfile, 'something.txt')
 
+    def test_unique_when_same_filename(self):
+        """
+        A FileField with unique=True shouldn't allow two instances with the
+        same name to be saved.
+        """
+        Document.objects.create(myfile='something.txt')
+        with self.assertRaises(IntegrityError):
+            Document.objects.create(myfile='something.txt')
+
     @unittest.skipIf(sys.platform.startswith('win'), "Windows doesn't support moving open files.")
     # The file's source and destination must be on the same filesystem.
     @override_settings(MEDIA_ROOT=temp.gettempdir())