Fixed #28982 -- Simplified code with and/or.

11 files changed, 29 insertions, 51 deletions

diff --git a/django/db/backends/mysql/schema.py b/django/db/backends/mysql/schema.py
index 24abdaf611..997fef1c0c 100644
--- a/django/db/backends/mysql/schema.py
+++ b/django/db/backends/mysql/schema.py
@@ -61,9 +61,7 @@ class DatabaseSchemaEditor(BaseDatabaseSchemaEditor):
                 field.get_internal_type() == 'ForeignKey' and
                 field.db_constraint):
             return False
-        if self._is_limited_data_type(field):
-            return False
-        return create_index
+        return not self._is_limited_data_type(field) and create_index
 
     def _delete_composed_index(self, model, fields, *args):
         """
diff --git a/django/db/backends/postgresql/creation.py b/django/db/backends/postgresql/creation.py
index a93bdbb4a1..0169fc5c1f 100644
--- a/django/db/backends/postgresql/creation.py
+++ b/django/db/backends/postgresql/creation.py
@@ -16,9 +16,7 @@ class DatabaseCreation(BaseDatabaseCreation):
             suffix += " ENCODING '{}'".format(encoding)
         if template:
             suffix += " TEMPLATE {}".format(self._quote_name(template))
-        if suffix:
-            suffix = "WITH" + suffix
-        return suffix
+        return suffix and "WITH" + suffix
 
     def sql_table_creation_suffix(self):
         test_settings = self.connection.settings_dict['TEST']
diff --git a/django/db/backends/postgresql/operations.py b/django/db/backends/postgresql/operations.py
index 06a46f4303..3b71cd4f2c 100644
--- a/django/db/backends/postgresql/operations.py
+++ b/django/db/backends/postgresql/operations.py
@@ -131,11 +131,9 @@ class DatabaseOperations(BaseDatabaseOperations):
         sql = []
         for sequence_info in sequences:
             table_name = sequence_info['table']
-            column_name = sequence_info['column']
-            if not column_name:
-                # This will be the case if it's an m2m using an autogenerated
-                # intermediate table (see BaseDatabaseIntrospection.sequence_list)
-                column_name = 'id'
+            # 'id' will be the case if it's an m2m using an autogenerated
+            # intermediate table (see BaseDatabaseIntrospection.sequence_list).
+            column_name = sequence_info['column'] or 'id'
             sql.append("%s setval(pg_get_serial_sequence('%s','%s'), 1, false);" % (
                 style.SQL_KEYWORD('SELECT'),
                 style.SQL_TABLE(self.quote_name(table_name)),
diff --git a/django/db/models/aggregates.py b/django/db/models/aggregates.py
index c7284359d4..8b67151663 100644
--- a/django/db/models/aggregates.py
+++ b/django/db/models/aggregates.py
@@ -31,15 +31,13 @@ class Aggregate(Func):
         return source_expressions
 
     def set_source_expressions(self, exprs):
-        if self.filter:
-            self.filter = exprs.pop()
+        self.filter = self.filter and exprs.pop()
         return super().set_source_expressions(exprs)
 
     def resolve_expression(self, query=None, allow_joins=True, reuse=None, summarize=False, for_save=False):
         # Aggregates are not allowed in UPDATE queries, so ignore for_save
         c = super().resolve_expression(query, allow_joins, reuse, summarize)
-        if c.filter:
-            c.filter = c.filter.resolve_expression(query, allow_joins, reuse, summarize)
+        c.filter = c.filter and c.filter.resolve_expression(query, allow_joins, reuse, summarize)
         if not summarize:
             # Call Aggregate.get_source_expressions() to avoid
             # returning self.filter and including that in this loop.
diff --git a/django/db/models/base.py b/django/db/models/base.py
index 972da7bb06..f88690f225 100644
--- a/django/db/models/base.py
+++ b/django/db/models/base.py
@@ -549,8 +549,7 @@ class Model(metaclass=ModelBase):
         self.__dict__.update(state)
 
     def _get_pk_val(self, meta=None):
-        if not meta:
-            meta = self._meta
+        meta = meta or self._meta
         return getattr(self, meta.pk.attname)
 
     def _set_pk_val(self, value):
@@ -852,7 +851,8 @@ class Model(metaclass=ModelBase):
             # exists.
             return update_fields is not None or filtered.exists()
         if self._meta.select_on_save and not forced_update:
-            if filtered.exists():
+            return (
+                filtered.exists() and
                 # It may happen that the object is deleted from the DB right after
                 # this check, causing the subsequent UPDATE to return zero matching
                 # rows. The same result can occur in some rare cases when the
@@ -860,9 +860,8 @@ class Model(metaclass=ModelBase):
                 # successfully (a row is matched and updated). In order to
                 # distinguish these two cases, the object's existence in the
                 # database is again checked for if the UPDATE query returns 0.
-                return filtered._update(values) > 0 or filtered.exists()
-            else:
-                return False
+                (filtered._update(values) > 0 or filtered.exists())
+            )
         return filtered._update(values) > 0
 
     def _do_insert(self, manager, using, fields, update_pk, raw):
diff --git a/django/db/models/fields/__init__.py b/django/db/models/fields/__init__.py
index 6ddd8f033a..da3fca1213 100644
--- a/django/db/models/fields/__init__.py
+++ b/django/db/models/fields/__init__.py
@@ -694,8 +694,7 @@ class Field(RegisterLookupMixin):
         return self._db_tablespace or settings.DEFAULT_INDEX_TABLESPACE
 
     def set_attributes_from_name(self, name):
-        if not self.name:
-            self.name = name
+        self.name = self.name or name
         self.attname, self.column = self.get_attname_column()
         self.concrete = self.column is not None
         if self.verbose_name is None and self.name:
diff --git a/django/db/models/fields/files.py b/django/db/models/fields/files.py
index 683a34ecd9..2d1d4b5e5f 100644
--- a/django/db/models/fields/files.py
+++ b/django/db/models/fields/files.py
@@ -314,9 +314,7 @@ class FileField(Field):
         if data is not None:
             # This value will be converted to str and stored in the
             # database, so leaving False as-is is not acceptable.
-            if not data:
-                data = ''
-            setattr(instance, self.name, data)
+            setattr(instance, self.name, data or '')
 
     def formfield(self, **kwargs):
         return super().formfield(**{
diff --git a/django/db/models/lookups.py b/django/db/models/lookups.py
index a9abd82cd9..7b01d06863 100644
--- a/django/db/models/lookups.py
+++ b/django/db/models/lookups.py
@@ -177,9 +177,7 @@ class FieldGetDbPrepValueMixin:
     def get_db_prep_lookup(self, value, connection):
         # For relational fields, use the output_field of the 'field' attribute.
         field = getattr(self.lhs.output_field, 'field', None)
-        get_db_prep_value = getattr(field, 'get_db_prep_value', None)
-        if not get_db_prep_value:
-            get_db_prep_value = self.lhs.output_field.get_db_prep_value
+        get_db_prep_value = getattr(field, 'get_db_prep_value', None) or self.lhs.output_field.get_db_prep_value
         return (
             '%s',
             [get_db_prep_value(v, connection, prepared=True) for v in value]
diff --git a/django/db/models/manager.py b/django/db/models/manager.py
index 5f897cd3ca..e7a956cc51 100644
--- a/django/db/models/manager.py
+++ b/django/db/models/manager.py
@@ -107,8 +107,7 @@ class BaseManager:
         })
 
     def contribute_to_class(self, model, name):
-        if not self.name:
-            self.name = name
+        self.name = self.name or name
         self.model = model
 
         setattr(model, name, ManagerDescriptor(self))
diff --git a/django/db/models/sql/compiler.py b/django/db/models/sql/compiler.py
index ddbcb0eb9a..a65c6e2596 100644
--- a/django/db/models/sql/compiler.py
+++ b/django/db/models/sql/compiler.py
@@ -521,8 +521,7 @@ class SQLCompiler:
                 if grouping:
                     if distinct_fields:
                         raise NotImplementedError('annotate() + distinct(fields) is not implemented.')
-                    if not order_by:
-                        order_by = self.connection.ops.force_no_ordering()
+                    order_by = order_by or self.connection.ops.force_no_ordering()
                     result.append('GROUP BY %s' % ', '.join(grouping))
 
                 if having:
@@ -588,8 +587,7 @@ class SQLCompiler:
         if opts is None:
             opts = self.query.get_meta()
         only_load = self.deferred_to_columns()
-        if not start_alias:
-            start_alias = self.query.get_initial_alias()
+        start_alias = start_alias or self.query.get_initial_alias()
         # The 'seen_models' is used to optimize checking the needed parent
         # alias for a given field. This also includes None -> start_alias to
         # be used by local fields.
@@ -657,8 +655,7 @@ class SQLCompiler:
         # of the field is specified.
         if field.is_relation and opts.ordering and getattr(field, 'attname', None) != name:
             # Firstly, avoid infinite loops.
-            if not already_seen:
-                already_seen = set()
+            already_seen = already_seen or set()
             join_tuple = tuple(getattr(self.query.alias_map[j], 'join_cols', None) for j in joins)
             if join_tuple in already_seen:
                 raise FieldError('Infinite loop caused by ordering.')
@@ -680,8 +677,7 @@ class SQLCompiler:
         same input, as the prefixes of get_ordering() and get_distinct() must
         match. Executing SQL where this is not true is an error.
         """
-        if not alias:
-            alias = self.query.get_initial_alias()
+        alias = alias or self.query.get_initial_alias()
         field, targets, opts, joins, path = self.query.setup_joins(
             pieces, opts, alias)
         alias = joins[-1]
@@ -1037,8 +1033,7 @@ class SQLCompiler:
         is needed, as the filters describe an empty set. In that case, None is
         returned, to avoid any unnecessary database interaction.
         """
-        if not result_type:
-            result_type = NO_RESULTS
+        result_type = result_type or NO_RESULTS
         try:
             sql, params = self.as_sql()
             if not sql:
diff --git a/django/db/models/sql/query.py b/django/db/models/sql/query.py
index bfee2256e6..e657594c86 100644
--- a/django/db/models/sql/query.py
+++ b/django/db/models/sql/query.py
@@ -805,9 +805,9 @@ class Query:
         if isinstance(self.group_by, tuple):
             self.group_by = tuple([col.relabeled_clone(change_map) for col in self.group_by])
         self.select = tuple([col.relabeled_clone(change_map) for col in self.select])
-        if self._annotations:
-            self._annotations = OrderedDict(
-                (key, col.relabeled_clone(change_map)) for key, col in self._annotations.items())
+        self._annotations = self._annotations and OrderedDict(
+            (key, col.relabeled_clone(change_map)) for key, col in self._annotations.items()
+        )
 
         # 2. Rename the alias in the internal table/alias datastructures.
         for old_alias, new_alias in change_map.items():
@@ -1061,9 +1061,7 @@ class Query:
         and get_transform().
         """
         # __exact is the default lookup if one isn't given.
-        if not lookups:
-            lookups = ['exact']
-
+        lookups = lookups or ['exact']
         for name in lookups[:-1]:
             lhs = self.try_transform(lhs, name)
         # First try get_lookup() so that the lookup takes precedence if the lhs
@@ -2050,10 +2048,10 @@ class Query:
         # used. The proper fix would be to defer all decisions where
         # is_nullable() is needed to the compiler stage, but that is not easy
         # to do currently.
-        if connections[DEFAULT_DB_ALIAS].features.interprets_empty_strings_as_nulls and field.empty_strings_allowed:
-            return True
-        else:
-            return field.null
+        return (
+            connections[DEFAULT_DB_ALIAS].features.interprets_empty_strings_as_nulls and
+            field.empty_strings_allowed
+        ) or field.null
 
 
 def get_order_dir(field, default='ASC'):