From 504ce3914fa86a58f29f5369a806f3fe56a0d59a Mon Sep 17 00:00:00 2001
From: Sergey Fedoseev <fedoseev.sergey@gmail.com>
Date: Sat, 15 Jul 2017 06:56:01 +0500
Subject: [PATCH] Fixed #28394 -- Allowed setting BaseExpression.output_field
(renamed from _output_field).
---
django/contrib/postgres/aggregates/general.py | 2 +-
django/contrib/postgres/fields/jsonb.py | 2 +-
django/contrib/postgres/search.py | 6 +--
django/db/models/expressions.py | 48 ++++++++++---------
django/db/models/functions/base.py | 4 +-
django/db/models/functions/datetime.py | 10 ++--
docs/releases/2.0.txt | 3 ++
tests/expressions/tests.py | 10 ++++
8 files changed, 49 insertions(+), 36 deletions(-)
diff --git a/django/contrib/postgres/aggregates/general.py b/django/contrib/postgres/aggregates/general.py
index 91835a9ca3..5bbf29e8ab 100644
--- a/django/contrib/postgres/aggregates/general.py
+++ b/django/contrib/postgres/aggregates/general.py
@@ -37,7 +37,7 @@ class BoolOr(Aggregate):
class JSONBAgg(Aggregate):
function = 'JSONB_AGG'
- _output_field = JSONField()
+ output_field = JSONField()
def convert_value(self, value, expression, connection, context):
if not value:
diff --git a/django/contrib/postgres/fields/jsonb.py b/django/contrib/postgres/fields/jsonb.py
index a3a3381745..a06187c4bc 100644
--- a/django/contrib/postgres/fields/jsonb.py
+++ b/django/contrib/postgres/fields/jsonb.py
@@ -115,7 +115,7 @@ class KeyTransform(Transform):
class KeyTextTransform(KeyTransform):
operator = '->>'
nested_operator = '#>>'
- _output_field = TextField()
+ output_field = TextField()
class KeyTransformTextLookupMixin:
diff --git a/django/contrib/postgres/search.py b/django/contrib/postgres/search.py
index 9d66976ae0..cc47dbfeb6 100644
--- a/django/contrib/postgres/search.py
+++ b/django/contrib/postgres/search.py
@@ -47,7 +47,7 @@ class SearchVectorCombinable:
class SearchVector(SearchVectorCombinable, Func):
function = 'to_tsvector'
arg_joiner = " || ' ' || "
- _output_field = SearchVectorField()
+ output_field = SearchVectorField()
config = None
def __init__(self, *expressions, **extra):
@@ -125,7 +125,7 @@ class SearchQueryCombinable:
class SearchQuery(SearchQueryCombinable, Value):
- _output_field = SearchQueryField()
+ output_field = SearchQueryField()
def __init__(self, value, output_field=None, *, config=None, invert=False):
self.config = config
@@ -170,7 +170,7 @@ class CombinedSearchQuery(SearchQueryCombinable, CombinedExpression):
class SearchRank(Func):
function = 'ts_rank'
- _output_field = FloatField()
+ output_field = FloatField()
def __init__(self, vector, query, **extra):
if not hasattr(vector, 'resolve_expression'):
diff --git a/django/db/models/expressions.py b/django/db/models/expressions.py
index 7e5c7313ce..dc2be87453 100644
--- a/django/db/models/expressions.py
+++ b/django/db/models/expressions.py
@@ -125,11 +125,11 @@ class BaseExpression:
# aggregate specific fields
is_summary = False
- _output_field = None
+ _output_field_resolved_to_none = False
def __init__(self, output_field=None):
if output_field is not None:
- self._output_field = output_field
+ self.output_field = output_field
def get_db_converters(self, connection):
return [self.convert_value] + self.output_field.get_db_converters(connection)
@@ -223,21 +223,23 @@ class BaseExpression:
@cached_property
def output_field(self):
"""Return the output type of this expressions."""
- if self._output_field_or_none is None:
- raise FieldError("Cannot resolve expression type, unknown output_field")
- return self._output_field_or_none
+ output_field = self._resolve_output_field()
+ if output_field is None:
+ self._output_field_resolved_to_none = True
+ raise FieldError('Cannot resolve expression type, unknown output_field')
+ return output_field
@cached_property
def _output_field_or_none(self):
"""
- Return the output field of this expression, or None if no output type
- can be resolved. Note that the 'output_field' property will raise
- FieldError if no type can be resolved, but this attribute allows for
- None values.
+ Return the output field of this expression, or None if
+ _resolve_output_field() didn't return an output type.
"""
- if self._output_field is None:
- self._output_field = self._resolve_output_field()
- return self._output_field
+ try:
+ return self.output_field
+ except FieldError:
+ if not self._output_field_resolved_to_none:
+ raise
def _resolve_output_field(self):
"""
@@ -249,9 +251,9 @@ class BaseExpression:
the type here is a convenience for the common case. The user should
supply their own output_field with more complex computations.
- If a source does not have an `_output_field` then we exclude it from
- this check. If all sources are `None`, then an error will be thrown
- higher up the stack in the `output_field` property.
+ If a source's output field resolves to None, exclude it from this check.
+ If all sources are None, then an error is raised higher up the stack in
+ the output_field property.
"""
sources_iter = (source for source in self.get_source_fields() if source is not None)
for output_field in sources_iter:
@@ -603,14 +605,14 @@ class Value(Expression):
def as_sql(self, compiler, connection):
connection.ops.check_expression_support(self)
val = self.value
- # check _output_field to avoid triggering an exception
- if self._output_field is not None:
+ output_field = self._output_field_or_none
+ if output_field is not None:
if self.for_save:
- val = self.output_field.get_db_prep_save(val, connection=connection)
+ val = output_field.get_db_prep_save(val, connection=connection)
else:
- val = self.output_field.get_db_prep_value(val, connection=connection)
- if hasattr(self._output_field, 'get_placeholder'):
- return self._output_field.get_placeholder(val, compiler, connection), [val]
+ val = output_field.get_db_prep_value(val, connection=connection)
+ if hasattr(output_field, 'get_placeholder'):
+ return output_field.get_placeholder(val, compiler, connection), [val]
if val is None:
# cx_Oracle does not always convert None to the appropriate
# NULL type (like in case expressions using numbers), so we
@@ -652,7 +654,7 @@ class RawSQL(Expression):
return [self]
def __hash__(self):
- h = hash(self.sql) ^ hash(self._output_field)
+ h = hash(self.sql) ^ hash(self.output_field)
for param in self.params:
h ^= hash(param)
return h
@@ -998,7 +1000,7 @@ class Exists(Subquery):
super().__init__(*args, **kwargs)
def __invert__(self):
- return type(self)(self.queryset, self.output_field, negated=(not self.negated), **self.extra)
+ return type(self)(self.queryset, negated=(not self.negated), **self.extra)
@property
def output_field(self):
diff --git a/django/db/models/functions/base.py b/django/db/models/functions/base.py
index c487bb4ab5..82a6083c58 100644
--- a/django/db/models/functions/base.py
+++ b/django/db/models/functions/base.py
@@ -24,12 +24,12 @@ class Cast(Func):
def as_sql(self, compiler, connection, **extra_context):
if 'db_type' not in extra_context:
- extra_context['db_type'] = self._output_field.db_type(connection)
+ extra_context['db_type'] = self.output_field.db_type(connection)
return super().as_sql(compiler, connection, **extra_context)
def as_mysql(self, compiler, connection):
extra_context = {}
- output_field_class = type(self._output_field)
+ output_field_class = type(self.output_field)
if output_field_class in self.mysql_types:
extra_context['db_type'] = self.mysql_types[output_field_class]
return self.as_sql(compiler, connection, **extra_context)
diff --git a/django/db/models/functions/datetime.py b/django/db/models/functions/datetime.py
index a56731e48f..52f1f73ae8 100644
--- a/django/db/models/functions/datetime.py
+++ b/django/db/models/functions/datetime.py
@@ -243,9 +243,8 @@ class TruncDate(TruncBase):
kind = 'date'
lookup_name = 'date'
- @cached_property
- def output_field(self):
- return DateField()
+ def __init__(self, *args, output_field=None, **kwargs):
+ super().__init__(*args, output_field=DateField(), **kwargs)
def as_sql(self, compiler, connection):
# Cast to date rather than truncate to date.
@@ -259,9 +258,8 @@ class TruncTime(TruncBase):
kind = 'time'
lookup_name = 'time'
- @cached_property
- def output_field(self):
- return TimeField()
+ def __init__(self, *args, output_field=None, **kwargs):
+ super().__init__(*args, output_field=TimeField(), **kwargs)
def as_sql(self, compiler, connection):
# Cast to date rather than truncate to date.
diff --git a/docs/releases/2.0.txt b/docs/releases/2.0.txt
index 8b41076aa7..81162e549f 100644
--- a/docs/releases/2.0.txt
+++ b/docs/releases/2.0.txt
@@ -551,6 +551,9 @@ Miscellaneous
in the cache backend as an intermediate class in ``CacheKeyWarning``'s
inheritance of ``RuntimeWarning``.
+* Renamed ``BaseExpression._output_field`` to ``output_field``. You may need
+ to update custom expressions.
+
.. _deprecated-features-2.0:
Features deprecated in 2.0
diff --git a/tests/expressions/tests.py b/tests/expressions/tests.py
index ed3e2ce628..532690ca8d 100644
--- a/tests/expressions/tests.py
+++ b/tests/expressions/tests.py
@@ -532,6 +532,16 @@ class BasicExpressionsTests(TestCase):
outer = Company.objects.filter(pk__in=Subquery(inner.values('pk')))
self.assertFalse(outer.exists())
+ def test_explicit_output_field(self):
+ class FuncA(Func):
+ output_field = models.CharField()
+
+ class FuncB(Func):
+ pass
+
+ expr = FuncB(FuncA())
+ self.assertEqual(expr.output_field, FuncA.output_field)
+
class IterableLookupInnerExpressionsTests(TestCase):
@classmethod