Fixed #27358 -- Added a system check to prevent FileField's upload_to from starting with a slash.

Thanks Frank Bijlsma for the initial patch.

1 files changed, 15 insertions, 0 deletions

diff --git a/django/db/models/fields/files.py b/django/db/models/fields/files.py
index e3497f2494..53a31c3ed6 100644
--- a/django/db/models/fields/files.py
+++ b/django/db/models/fields/files.py
@@ -240,6 +240,7 @@ class FileField(Field):
     def check(self, **kwargs):
         errors = super(FileField, self).check(**kwargs)
         errors.extend(self._check_primary_key())
+        errors.extend(self._check_upload_to())
         return errors
 
     def _check_primary_key(self):
@@ -254,6 +255,20 @@ class FileField(Field):
         else:
             return []
 
+    def _check_upload_to(self):
+        if isinstance(self.upload_to, six.string_types) and self.upload_to[0] == '/':
+            return [
+                checks.Error(
+                    "%s's 'upload_to' argument must be a relative path, not an "
+                    "absolute path." % self.__class__.__name__,
+                    obj=self,
+                    id='fields.E202',
+                    hint='Remove the leading slash.',
+                )
+            ]
+        else:
+            return []
+
     def deconstruct(self):
         name, path, args, kwargs = super(FileField, self).deconstruct()
         if kwargs.get("max_length") == 100: