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| author | Simon Charette <simon.charette@zapier.com> | 2019-05-12 17:17:47 -0400 |
|---|---|---|
| committer | Mariusz Felisiak <felisiak.mariusz@gmail.com> | 2020-07-15 10:58:29 +0200 |
| commit | 1e38f1191de21b6e96736f58df57dfb851a28c1f (patch) | |
| tree | 99b2c92d87d4d351d1f180e93a543b8903ec28d3 /docs/ref/models | |
| parent | d08e6f55e3a986a8d4b3a58431d9615c7bc81eaa (diff) | |
Fixed #30446 -- Resolved Value.output_field for stdlib types.
This required implementing a limited form of dynamic dispatch to combine
expressions with numerical output. Refs #26355 should eventually provide
a better interface for that.
Diffstat (limited to 'docs/ref/models')
| -rw-r--r-- | docs/ref/models/expressions.txt | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/docs/ref/models/expressions.txt b/docs/ref/models/expressions.txt index 252966bb6c..31d2572288 100644 --- a/docs/ref/models/expressions.txt +++ b/docs/ref/models/expressions.txt @@ -484,7 +484,15 @@ The ``output_field`` argument should be a model field instance, like after it's retrieved from the database. Usually no arguments are needed when instantiating the model field as any arguments relating to data validation (``max_length``, ``max_digits``, etc.) will not be enforced on the expression's -output value. +output value. If no ``output_field`` is specified it will be tentatively +inferred from the :py:class:`type` of the provided ``value``, if possible. For +example, passing an instance of :py:class:`datetime.datetime` as ``value`` +would default ``output_field`` to :class:`~django.db.models.DateTimeField`. + +.. versionchanged:: 3.2 + + Support for inferring a default ``output_field`` from the type of ``value`` + was added. ``ExpressionWrapper()`` expressions ----------------------------------- |