diff options
Diffstat (limited to 'django/db/backends/base')
| -rw-r--r-- | django/db/backends/base/features.py | 5 | ||||
| -rw-r--r-- | django/db/backends/base/schema.py | 35 |
2 files changed, 36 insertions, 4 deletions
diff --git a/django/db/backends/base/features.py b/django/db/backends/base/features.py index 11dd079110..79abad82cf 100644 --- a/django/db/backends/base/features.py +++ b/django/db/backends/base/features.py @@ -27,6 +27,11 @@ class BaseDatabaseFeatures: # Does the backend allow inserting duplicate rows when a unique_together # constraint exists and some fields are nullable but not all of them? supports_partially_nullable_unique_constraints = True + + # Does the backend supports specifying whether NULL values should be + # considered distinct in unique constraints? + supports_nulls_distinct_unique_constraints = False + # Does the backend support initially deferrable unique constraints? supports_deferrable_unique_constraints = False diff --git a/django/db/backends/base/schema.py b/django/db/backends/base/schema.py index 9329ee0971..5fe26d068f 100644 --- a/django/db/backends/base/schema.py +++ b/django/db/backends/base/schema.py @@ -129,7 +129,7 @@ class BaseDatabaseSchemaEditor: ) sql_create_unique_index = ( "CREATE UNIQUE INDEX %(name)s ON %(table)s " - "(%(columns)s)%(include)s%(condition)s" + "(%(columns)s)%(include)s%(condition)s%(nulls_distinct)s" ) sql_rename_index = "ALTER INDEX %(old_name)s RENAME TO %(new_name)s" sql_delete_index = "DROP INDEX %(name)s" @@ -1675,12 +1675,20 @@ class BaseDatabaseSchemaEditor: if deferrable == Deferrable.IMMEDIATE: return " DEFERRABLE INITIALLY IMMEDIATE" + def _unique_index_nulls_distinct_sql(self, nulls_distinct): + if nulls_distinct is False: + return " NULLS NOT DISTINCT" + elif nulls_distinct is True: + return " NULLS DISTINCT" + return "" + def _unique_supported( self, condition=None, deferrable=None, include=None, expressions=None, + nulls_distinct=None, ): return ( (not condition or self.connection.features.supports_partial_indexes) @@ -1692,6 +1700,10 @@ class BaseDatabaseSchemaEditor: and ( not expressions or self.connection.features.supports_expression_indexes ) + and ( + nulls_distinct is None + or self.connection.features.supports_nulls_distinct_unique_constraints + ) ) def _unique_sql( @@ -1704,17 +1716,26 @@ class BaseDatabaseSchemaEditor: include=None, opclasses=None, expressions=None, + nulls_distinct=None, ): if not self._unique_supported( condition=condition, deferrable=deferrable, include=include, expressions=expressions, + nulls_distinct=nulls_distinct, ): return None - if condition or include or opclasses or expressions: - # Databases support conditional, covering, and functional unique - # constraints via a unique index. + + if ( + condition + or include + or opclasses + or expressions + or nulls_distinct is not None + ): + # Databases support conditional, covering, functional unique, + # and nulls distinct constraints via a unique index. sql = self._create_unique_sql( model, fields, @@ -1723,6 +1744,7 @@ class BaseDatabaseSchemaEditor: include=include, opclasses=opclasses, expressions=expressions, + nulls_distinct=nulls_distinct, ) if sql: self.deferred_sql.append(sql) @@ -1746,12 +1768,14 @@ class BaseDatabaseSchemaEditor: include=None, opclasses=None, expressions=None, + nulls_distinct=None, ): if not self._unique_supported( condition=condition, deferrable=deferrable, include=include, expressions=expressions, + nulls_distinct=nulls_distinct, ): return None @@ -1782,6 +1806,7 @@ class BaseDatabaseSchemaEditor: condition=self._index_condition_sql(condition), deferrable=self._deferrable_constraint_sql(deferrable), include=self._index_include_sql(model, include), + nulls_distinct=self._unique_index_nulls_distinct_sql(nulls_distinct), ) def _unique_constraint_name(self, table, columns, quote=True): @@ -1804,12 +1829,14 @@ class BaseDatabaseSchemaEditor: include=None, opclasses=None, expressions=None, + nulls_distinct=None, ): if not self._unique_supported( condition=condition, deferrable=deferrable, include=include, expressions=expressions, + nulls_distinct=nulls_distinct, ): return None if condition or include or opclasses or expressions: |