diff options
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/topics/migrations.txt | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/docs/topics/migrations.txt b/docs/topics/migrations.txt index 8a5359fec4..40ce520a03 100644 --- a/docs/topics/migrations.txt +++ b/docs/topics/migrations.txt @@ -491,11 +491,30 @@ Django can serialize the following: - Any class reference - Anything with a custom ``deconstruct()`` method (:ref:`see below <custom-deconstruct-method>`) +Django can serialize the following on Python 3 only: + +- Unbound methods used from within the class body (see below) + Django cannot serialize: - Arbitrary class instances (e.g. ``MyClass(4.3, 5.7)``) - Lambdas +Due to the fact ``__qualname__`` was only introduced in Python 3, Django can only +serialize the following pattern (an unbound method used within the class body) +on Python 3, and will fail to serialize a reference to it on Python 2:: + + class MyModel(models.Model): + + def upload_to(self): + return "something dynamic" + + my_file = models.FileField(upload_to=upload_to) + +If you are using Python 2, we recommend you move your methods for upload_to +and similar arguments that accept callables (e.g. ``default``) to live in +the main module body, rather than the class body. + .. _custom-deconstruct-method: Adding a deconstruct() method |