Fix #15646: Document that a FileField's full path can't be relied upon until its model has been saved to the database. Thanks poirier.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@17113 bcc190cf-cafb-0310-a4f2-bffc1f526a37

docs/ref/models/fields.txt

@@ -572,6 +572,11 @@ information on the available attributes and methods, see the
 :class:`~django.core.files.File` class reference and the :doc:`/topics/files`
 topic guide.
 
+.. note::
+    The file is saved as part of saving the model in the database, so the actual
+    file name used on disk cannot be relied on until after the model has been
+    saved.
+
 The uploaded file's relative URL can be obtained using the
 :attr:`~django.db.models.fields.FileField.url` attribute. Internally,
 this calls the :meth:`~django.core.files.storage.Storage.url` method of the

docs/topics/files.txt

@@ -45,6 +45,12 @@ the details of the attached photo::
 This object -- ``car.photo`` in the example -- is a ``File`` object, which means
 it has all the methods and attributes described below.
 
+.. note::
+    The file is saved as part of saving the model in the database, so the actual
+    file name used on disk cannot be relied on until after the model has been
+    saved.
+
+
 The ``File`` object
 ===================