diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 254c8245..3f1686a2 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -1,9 +1,9 @@
 repos:
 -   repo: https://github.com/pycqa/isort
-    rev: 7.0.0
+    rev: 8.0.1
     hooks:
     -   id: isort
 -   repo: https://github.com/python/black
-    rev: 25.11.0
+    rev: 26.3.1
     hooks:
     -   id: black
diff --git a/dev-requirements.txt b/dev-requirements.txt
index a30293e4..5555c510 100644
--- a/dev-requirements.txt
+++ b/dev-requirements.txt
@@ -1,5 +1,5 @@
 coverage[toml]
-black == 24.4.2
+black == 26.3.1
 pre-commit
 pyperf
 sphinx
diff --git a/pyproject.toml b/pyproject.toml
index 1da2ac6a..4ef78f51 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -11,7 +11,7 @@ classifiers = [
     "License :: OSI Approved :: GNU Lesser General Public License v3 (LGPLv3)",
     "Operating System :: OS Independent",
 ]
-requires-python = ">=3.10"
+requires-python = ">=3.10"  # Remember to bump Black's target-version below when updating this.
 dependencies = [
     "SQLAlchemy >=2.0, <2.1",
     "alembic >=1.7",
@@ -60,6 +60,7 @@ branch = true
 ignore_errors = true
 
 [tool.black]
+target-version = ["py310"]
 line-length = 120
 force-exclude = '\.git|version.py'
 
diff --git a/spinedb_api/__init__.py b/spinedb_api/__init__.py
index a272df0e..925567a2 100644
--- a/spinedb_api/__init__.py
+++ b/spinedb_api/__init__.py
@@ -10,7 +10,7 @@
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
 
-""" A package to interact with Spine DBs. """
+"""A package to interact with Spine DBs."""
 
 from .db_mapping import DatabaseMapping
 from .exception import (
diff --git a/spinedb_api/alembic/versions/39e860a11b05_add_alternatives_and_scenarios.py b/spinedb_api/alembic/versions/39e860a11b05_add_alternatives_and_scenarios.py
index 2b0fc29c..13ed2fed 100644
--- a/spinedb_api/alembic/versions/39e860a11b05_add_alternatives_and_scenarios.py
+++ b/spinedb_api/alembic/versions/39e860a11b05_add_alternatives_and_scenarios.py
@@ -102,8 +102,7 @@ def alter_tables_after_update():
         date = datetime.now(timezone.utc)
         conn = op.get_bind()
         conn.execute(
-            text(
-                """
+            text("""
             UPDATE next_id
             SET
                 user = :user,
@@ -111,8 +110,7 @@ def alter_tables_after_update():
                 alternative_id = 2,
                 scenario_id = 1,
                 scenario_alternative_id = 1
-            """
-            ),
+            """),
             {
                 "user": user,
                 "date": date,
diff --git a/spinedb_api/alembic/versions/bba1e2ef5153_move_to_entity_based_design.py b/spinedb_api/alembic/versions/bba1e2ef5153_move_to_entity_based_design.py
index f460f1c4..a2ddfbe1 100644
--- a/spinedb_api/alembic/versions/bba1e2ef5153_move_to_entity_based_design.py
+++ b/spinedb_api/alembic/versions/bba1e2ef5153_move_to_entity_based_design.py
@@ -142,33 +142,19 @@ def insert_into_new_tables():
     ]
     op.bulk_insert(meta.tables["entity_class"], entity_classes)
     # Id mappings
-    obj_cls_to_ent_cls = {
-        r.object_class_id: r.entity_class_id
-        for r in conn.execute(
-            text(
-                """
+    obj_cls_to_ent_cls = {r.object_class_id: r.entity_class_id for r in conn.execute(text("""
             SELECT object_class.id AS object_class_id, entity_class.id AS entity_class_id
             FROM object_class, entity_class
             WHERE entity_class.type_id = 1
             AND object_class.name = entity_class.name
-            """
-            )
-        )
-    }
-    rel_cls_to_ent_cls = {
-        r.relationship_class_id: r.entity_class_id
-        for r in conn.execute(
-            text(
-                """
+            """))}
+    rel_cls_to_ent_cls = {r.relationship_class_id: r.entity_class_id for r in conn.execute(text("""
             SELECT relationship_class.id AS relationship_class_id, entity_class.id AS entity_class_id
             FROM relationship_class, entity_class
             WHERE entity_class.type_id = 2
             AND relationship_class.name = entity_class.name
             GROUP BY relationship_class_id, entity_class_id
-            """
-            )
-        )
-    }
+            """))}
     temp_relationship_classes = [
         {"entity_class_id": r.id, "type_id": 2, "commit_id": r.commit_id}
         for r in conn.execute(text("SELECT id, commit_id FROM entity_class WHERE type_id = 2"))
@@ -195,33 +181,19 @@ def insert_into_new_tables():
     ]
     op.bulk_insert(meta.tables["entity"], entities)
     # Id mappings
-    obj_to_ent = {
-        r.object_id: r.entity_id
-        for r in conn.execute(
-            text(
-                """
+    obj_to_ent = {r.object_id: r.entity_id for r in conn.execute(text("""
             SELECT object.id AS object_id, entity.id AS entity_id
             FROM object, entity
             WHERE entity.type_id = 1
             AND object.name = entity.name
-            """
-            )
-        )
-    }
-    rel_to_ent = {
-        r.relationship_id: r.entity_id
-        for r in conn.execute(
-            text(
-                """
+            """))}
+    rel_to_ent = {r.relationship_id: r.entity_id for r in conn.execute(text("""
             SELECT relationship.id AS relationship_id, entity.id AS entity_id
             FROM relationship, entity
             WHERE entity.type_id = 2
             AND relationship.name = entity.name
             GROUP BY relationship_id, entity_id
-            """
-            )
-        )
-    }
+            """))}
     temp_relationships = [
         {"entity_id": r.id, "entity_class_id": r.class_id, "type_id": 2, "commit_id": r.commit_id}
         for r in conn.execute(text("SELECT id, class_id, commit_id FROM entity WHERE type_id = 2"))
@@ -236,15 +208,11 @@ def insert_into_new_tables():
             "member_class_id": obj_cls_to_ent_cls[r.object_class_id],
             "commit_id": r.commit_id,
         }
-        for r in conn.execute(
-            text(
-                """
+        for r in conn.execute(text("""
             SELECT r.id, r.class_id, r.dimension, o.class_id AS object_class_id, r.object_id, r.commit_id
             FROM relationship AS r, object AS o
             WHERE r.object_id = o.id
-            """
-            )
-        )
+            """))
     ]
     op.bulk_insert(meta.tables["relationship_entity"], relationship_entities)
     # Return metadata and id mappings
@@ -309,12 +277,10 @@ def update_tables(meta, obj_cls_to_ent_cls, rel_cls_to_ent_cls, obj_to_ent, rel_
             {"entity_class_id": entity_class_id, "object_class_id": object_class_id},
         )
         conn.execute(
-            text(
-                """
+            text("""
             UPDATE parameter_definition SET entity_class_id = :entity_class_id
             WHERE object_class_id = :object_class_id
-            """
-            ),
+            """),
             {
                 "entity_class_id": entity_class_id,
                 "object_class_id": object_class_id,
@@ -322,12 +288,10 @@ def update_tables(meta, obj_cls_to_ent_cls, rel_cls_to_ent_cls, obj_to_ent, rel_
         )
     for relationship_class_id, entity_class_id in rel_cls_to_ent_cls.items():
         conn.execute(
-            text(
-                """
+            text("""
             UPDATE parameter_definition SET entity_class_id = :entity_class_id
             WHERE relationship_class_id = :relationship_class_id
-            """
-            ),
+            """),
             {
                 "entity_class_id": entity_class_id,
                 "relationship_class_id": relationship_class_id,
@@ -343,12 +307,10 @@ def update_tables(meta, obj_cls_to_ent_cls, rel_cls_to_ent_cls, obj_to_ent, rel_
         )
         entity_class_id = ent_to_ent_cls[entity_id]
         conn.execute(
-            text(
-                """
+            text("""
             UPDATE parameter_value SET entity_id = :entity_id, entity_class_id = :entity_class_id
             WHERE object_id = :object_id
-            """
-            ),
+            """),
             {
                 "entity_id": entity_id,
                 "entity_class_id": entity_class_id,
@@ -358,12 +320,10 @@ def update_tables(meta, obj_cls_to_ent_cls, rel_cls_to_ent_cls, obj_to_ent, rel_
     for relationship_id, entity_id in rel_to_ent.items():
         entity_class_id = ent_to_ent_cls[entity_id]
         conn.execute(
-            text(
-                """
+            text("""
             UPDATE parameter_value SET entity_id = :entity_id, entity_class_id = :entity_class_id
             WHERE relationship_id = :relationship_id
-            """
-            ),
+            """),
             {
                 "entity_id": entity_id,
                 "entity_class_id": entity_class_id,
@@ -383,8 +343,7 @@ def update_tables(meta, obj_cls_to_ent_cls, rel_cls_to_ent_cls, obj_to_ent, rel_
     user = "alembic"
     date = datetime.now(timezone.utc)
     conn.execute(
-        text(
-            """
+        text("""
         UPDATE next_id
         SET
             user = :user,
@@ -393,8 +352,7 @@ def update_tables(meta, obj_cls_to_ent_cls, rel_cls_to_ent_cls, obj_to_ent, rel_
             entity_type_id = 3,
             entity_class_id = :entity_class_id,
             entity_id = :entity_id
-        """
-        ),
+        """),
         {
             "user": user,
             "date": date,
diff --git a/spinedb_api/arrow_value.py b/spinedb_api/arrow_value.py
index 7dae65e9..01e68bea 100644
--- a/spinedb_api/arrow_value.py
+++ b/spinedb_api/arrow_value.py
@@ -18,6 +18,7 @@
   This is highly experimental API.
 
 """
+
 from collections import defaultdict
 from collections.abc import Callable, Iterable
 import datetime
diff --git a/spinedb_api/dataframes.py b/spinedb_api/dataframes.py
index 4acc04c0..30af6ad3 100644
--- a/spinedb_api/dataframes.py
+++ b/spinedb_api/dataframes.py
@@ -104,6 +104,7 @@
         ).subquery()
         df = fetch_as_dataframe(db_map, final_query, maps)
 """
+
 from __future__ import annotations
 import collections
 from typing import Any, Union
diff --git a/spinedb_api/db_mapping.py b/spinedb_api/db_mapping.py
index d6aeb4fb..30804c54 100644
--- a/spinedb_api/db_mapping.py
+++ b/spinedb_api/db_mapping.py
@@ -15,6 +15,7 @@
 If you're planning to use this class, it is probably a good idea to first familiarize yourself a little bit with the
 :ref:`db_mapping_schema`.
 """
+
 from __future__ import annotations
 from collections.abc import Callable
 from datetime import datetime, timezone
@@ -1418,8 +1419,7 @@ def type_(f_dict):
         factory = ITEM_CLASS_BY_TYPE[item_type]
         a = _a(item_type)
         get_kwargs = _kwargs(_uq_fields(factory))
-        child = astroid.extract_node(
-            f'''
+        child = astroid.extract_node(f'''
             def {item_type}(self, **kwargs):
                 """Returns {a} `{item_type}` item matching the keyword arguments.
 
@@ -1429,11 +1429,9 @@ def {item_type}(self, **kwargs):
                 Returns:
                     :class:`PublicItem`
                 """
-            '''
-        )
+            ''')
         children.setdefault("get", []).append(child)
-        child = astroid.extract_node(
-            f'''
+        child = astroid.extract_node(f'''
             def find_{_pluralize(item_type)}(self, **kwargs):
                 """Finds and returns all `{item_type}` items matching the keyword arguments.
 
@@ -1443,12 +1441,10 @@ def find_{_pluralize(item_type)}(self, **kwargs):
                 Returns:
                     list of :class:`PublicItem`: The items.
                 """
-            '''
-        )
+            ''')
         children.setdefault("find", []).append(child)
         add_kwargs = _kwargs(factory.fields)
-        child = astroid.extract_node(
-            f'''
+        child = astroid.extract_node(f'''
             def add_{item_type}(self, **kwargs):
                 """Adds {a} `{item_type}` item to the in-memory mapping.
 
@@ -1458,23 +1454,19 @@ def add_{item_type}(self, **kwargs):
                 Returns:
                     :class:`PublicItem`: The added item.
                 """
-            '''
-        )
+            ''')
         children.setdefault("add", []).append(child)
-        child = astroid.extract_node(
-            f'''
+        child = astroid.extract_node(f'''
             def add_{_pluralize(item_type)}(self, items):
                 """Adds multiple `{item_type}` items to the in-memory mapping.
 
                 Args:
                     items (list of dict): items to add
                 """
-            '''
-        )
+            ''')
         children.setdefault("add many", []).append(child)
         update_kwargs = f"id (int): The id of the item to update.\n{padding}" + _kwargs(factory.fields)
-        child = astroid.extract_node(
-            f'''
+        child = astroid.extract_node(f'''
             def update_{item_type}(self, **kwargs):
                 """Updates {a} `{item_type}` item in the in-memory mapping.
 
@@ -1484,22 +1476,18 @@ def update_{item_type}(self, **kwargs):
                 Returns:
                     :class:`PublicItem` or None: The updated item or None if nothing was updated.
                 """
-            '''
-        )
+            ''')
         children.setdefault("update", []).append(child)
-        child = astroid.extract_node(
-            f'''
+        child = astroid.extract_node(f'''
             def update_{_pluralize(item_type)}(self, items):
                 """Updates multiple `{item_type}` items in the in-memory mapping.
 
                 Args:
                     items (list of dict): items to update
                 """
-            '''
-        )
+            ''')
         children.setdefault("update many", []).append(child)
-        child = astroid.extract_node(
-            f'''
+        child = astroid.extract_node(f'''
             def add_or_update_{item_type}(self, **kwargs):
                 """Adds {a} `{item_type}` item to the in-memory mapping if it doesn't exist;
                 otherwise updates the current one.
@@ -1510,11 +1498,9 @@ def add_or_update_{item_type}(self, **kwargs):
                 Returns:
                     :class:`PublicItem` or None: The added or updated item or None if nothing was added or updated.
                 """
-            '''
-        )
+            ''')
         children.setdefault("add_or_update", []).append(child)
-        child = astroid.extract_node(
-            f'''
+        child = astroid.extract_node(f'''
             def add_or_update_{_pluralize(item_type)}(self, items):
                 """Adds multiple `{item_type}` items to the in-memory mapping if they don't exist;
                 otherwise updates the items.
@@ -1522,33 +1508,27 @@ def add_or_update_{_pluralize(item_type)}(self, items):
                 Args:
                     items(list of dict): items to add or update
                 """
-            '''
-        )
+            ''')
         children.setdefault("add_or_update many", []).append(child)
-        child = astroid.extract_node(
-            f'''
+        child = astroid.extract_node(f'''
             def remove_{item_type}(self, **kwargs):
                 """Removes {a} `{item_type}` item from the in-memory mapping.
 
                 Args:
                     {add_kwargs}
                 """
-            '''
-        )
+            ''')
         children.setdefault("remove", []).append(child)
-        child = astroid.extract_node(
-            f'''
+        child = astroid.extract_node(f'''
             def remove_{_pluralize(item_type)}(self, items):
                 """Removes multiple `{item_type}` items from the in-memory mapping.
 
                 Args:
                     items(list of dict): items to remove
                 """
-            '''
-        )
+            ''')
         children.setdefault("remove many", []).append(child)
-        child = astroid.extract_node(
-            f'''
+        child = astroid.extract_node(f'''
             def restore_{item_type}(self, **kwargs):
                 """Restores a previously removed `{item_type}` item into the in-memory mapping.
 
@@ -1558,19 +1538,16 @@ def restore_{item_type}(self, **kwargs):
                 Returns:
                     :class:`PublicItem`: The restored item.
                 """
-            '''
-        )
+            ''')
         children.setdefault("restore", []).append(child)
-        child = astroid.extract_node(
-            f'''
+        child = astroid.extract_node(f'''
             def restore_{_pluralize(item_type)}(self, items):
                 """Restores multiple `{item_type}` items back into the in-memory mapping.
 
                 Args:
                     items(list of dict): items to restore
                 """
-            '''
-        )
+            ''')
         children.setdefault("restore many", []).append(child)
     for child_list in children.values():
         for child in child_list:
diff --git a/spinedb_api/db_mapping_helpers.py b/spinedb_api/db_mapping_helpers.py
index 0f2c7daf..a7bde905 100644
--- a/spinedb_api/db_mapping_helpers.py
+++ b/spinedb_api/db_mapping_helpers.py
@@ -13,6 +13,7 @@
 This module defines functions, classes and other utilities
 that may be useful with :class:`.db_mapping.DatabaseMapping`.
 """
+
 from spinedb_api.db_mapping_base import PublicItem
 from spinedb_api.mapped_items import ParameterDefinitionItem
 from spinedb_api.parameter_value import UNPARSED_NULL_VALUE, Map, from_database_to_dimension_count, type_for_value
diff --git a/spinedb_api/export_functions.py b/spinedb_api/export_functions.py
index 4480ee1a..c1f1fbe4 100644
--- a/spinedb_api/export_functions.py
+++ b/spinedb_api/export_functions.py
@@ -10,6 +10,7 @@
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
 """Functions for exporting data from a Spine database in a standard format."""
+
 from collections.abc import Callable, Iterable, Iterator
 from operator import itemgetter
 from typing import Any, Optional, TypeAlias, Union
diff --git a/spinedb_api/export_mapping/export_mapping.py b/spinedb_api/export_mapping/export_mapping.py
index 416610d9..d295c985 100644
--- a/spinedb_api/export_mapping/export_mapping.py
+++ b/spinedb_api/export_mapping/export_mapping.py
@@ -10,6 +10,7 @@
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
 """Contains export mappings for database items such as entities, entity classes and parameter values."""
+
 from __future__ import annotations
 from collections.abc import Callable, Iterator
 from contextlib import suppress
diff --git a/spinedb_api/export_mapping/generator.py b/spinedb_api/export_mapping/generator.py
index e8e7ca66..6242f16c 100644
--- a/spinedb_api/export_mapping/generator.py
+++ b/spinedb_api/export_mapping/generator.py
@@ -9,7 +9,8 @@
 # Public License for more details. You should have received a copy of the GNU Lesser General Public License along with
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
-""" Contains generator functions that convert a Spine database into rows of tabular data. """
+"""Contains generator functions that convert a Spine database into rows of tabular data."""
+
 from collections.abc import Iterator
 from copy import deepcopy
 from typing import Any, Optional
diff --git a/spinedb_api/export_mapping/group_functions.py b/spinedb_api/export_mapping/group_functions.py
index 53021e6b..f8eaf9ba 100644
--- a/spinedb_api/export_mapping/group_functions.py
+++ b/spinedb_api/export_mapping/group_functions.py
@@ -9,7 +9,8 @@
 # Public License for more details. You should have received a copy of the GNU Lesser General Public License along with
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
-""" Contains functions to group values in pivot tables with hidden columns or rows. """
+"""Contains functions to group values in pivot tables with hidden columns or rows."""
+
 from typing import Any, ClassVar, Type
 import numpy as np
 
diff --git a/spinedb_api/export_mapping/pivot.py b/spinedb_api/export_mapping/pivot.py
index 7a3f326f..1cdd1eca 100644
--- a/spinedb_api/export_mapping/pivot.py
+++ b/spinedb_api/export_mapping/pivot.py
@@ -9,7 +9,8 @@
 # Public License for more details. You should have received a copy of the GNU Lesser General Public License along with
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
-""" Contains functions and methods to turn a regular export table into a pivot table """
+"""Contains functions and methods to turn a regular export table into a pivot table"""
+
 from copy import deepcopy
 from ..mapping import Position, is_pivoted, is_regular, unflatten, value_index
 from .export_mapping import EntityMapping
diff --git a/spinedb_api/export_mapping/settings.py b/spinedb_api/export_mapping/settings.py
index eed32bea..82f26700 100644
--- a/spinedb_api/export_mapping/settings.py
+++ b/spinedb_api/export_mapping/settings.py
@@ -10,6 +10,7 @@
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
 """Contains convenience functions to set up different database export schemes."""
+
 from itertools import takewhile
 from ..mapping import unflatten
 from .export_mapping import (
diff --git a/spinedb_api/filters/alternative_filter.py b/spinedb_api/filters/alternative_filter.py
index 63aaf20a..7de85d7d 100644
--- a/spinedb_api/filters/alternative_filter.py
+++ b/spinedb_api/filters/alternative_filter.py
@@ -15,6 +15,7 @@
 Alternative filter is defined by selected alternatives.
 It lets everything depending on the selected alternatives through and filters out the rest.
 """
+
 from collections.abc import Iterable
 from functools import partial
 from sqlalchemy import Integer, and_, cast, func, literal, or_, select, union_all
diff --git a/spinedb_api/filters/renamer.py b/spinedb_api/filters/renamer.py
index b97e3409..3f1e75d2 100644
--- a/spinedb_api/filters/renamer.py
+++ b/spinedb_api/filters/renamer.py
@@ -14,6 +14,7 @@
 
 Currently, entity classes and parameter can be renamed.
 """
+
 from functools import partial
 from sqlalchemy import case
 
diff --git a/spinedb_api/filters/tools.py b/spinedb_api/filters/tools.py
index 3d17cecc..44b78a05 100644
--- a/spinedb_api/filters/tools.py
+++ b/spinedb_api/filters/tools.py
@@ -9,7 +9,8 @@
 # Public License for more details. You should have received a copy of the GNU Lesser General Public License along with
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
-""" This module contains tools and utilities to work with filters. """
+"""This module contains tools and utilities to work with filters."""
+
 from __future__ import annotations
 from collections.abc import Iterable
 from itertools import dropwhile, takewhile
diff --git a/spinedb_api/filters/value_transformer.py b/spinedb_api/filters/value_transformer.py
index b10a1c93..db9202c0 100644
--- a/spinedb_api/filters/value_transformer.py
+++ b/spinedb_api/filters/value_transformer.py
@@ -19,6 +19,7 @@
 - ``invert`` inverts the value
 - ``generate_index`` uses a Python expression to reindex an indexed value
 """
+
 from collections.abc import Sequence
 from functools import partial
 from numbers import Number
diff --git a/spinedb_api/graph_layout_generator.py b/spinedb_api/graph_layout_generator.py
index f52427b2..5043c1a0 100644
--- a/spinedb_api/graph_layout_generator.py
+++ b/spinedb_api/graph_layout_generator.py
@@ -13,6 +13,7 @@
 """
 This module defines the :class:`.GraphLayoutGenerator` class.
 """
+
 import math
 import numpy as np
 from numpy import atleast_1d as arr
diff --git a/spinedb_api/import_functions.py b/spinedb_api/import_functions.py
index 8fd1f32b..e200c7d2 100644
--- a/spinedb_api/import_functions.py
+++ b/spinedb_api/import_functions.py
@@ -15,6 +15,7 @@
 This functionality is equivalent to the one provided by :meth:`.DatabaseMapping.add_update_item`,
 but the syntax is a little more compact.
 """
+
 from collections import defaultdict
 from collections.abc import Callable, Iterable, Iterator, Sequence
 from contextlib import suppress
diff --git a/spinedb_api/import_mapping/generator.py b/spinedb_api/import_mapping/generator.py
index ad8e177d..85776878 100644
--- a/spinedb_api/import_mapping/generator.py
+++ b/spinedb_api/import_mapping/generator.py
@@ -14,6 +14,7 @@
 Contains `get_mapped_data()` that converts rows of tabular data into a dictionary for import to a Spine DB,
 using ``import_functions.import_data()``
 """
+
 from collections.abc import Callable, Iterable
 from copy import deepcopy
 from itertools import dropwhile
diff --git a/spinedb_api/import_mapping/import_mapping.py b/spinedb_api/import_mapping/import_mapping.py
index 99a709c1..82e68a09 100644
--- a/spinedb_api/import_mapping/import_mapping.py
+++ b/spinedb_api/import_mapping/import_mapping.py
@@ -10,6 +10,7 @@
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
 """Contains import mappings for database items such as entities, entity classes and parameter values."""
+
 from __future__ import annotations
 from collections.abc import Iterable
 from dataclasses import dataclass, field
diff --git a/spinedb_api/import_mapping/import_mapping_compat.py b/spinedb_api/import_mapping/import_mapping_compat.py
index 329e9b2d..441ffcb7 100644
--- a/spinedb_api/import_mapping/import_mapping_compat.py
+++ b/spinedb_api/import_mapping/import_mapping_compat.py
@@ -11,6 +11,7 @@
 ######################################################################################################################
 
 """Functions for creating import mappings from dicts."""
+
 from ..mapping import to_dict as import_mapping_to_dict
 from .import_mapping import (
     AlternativeMapping,
diff --git a/spinedb_api/purge.py b/spinedb_api/purge.py
index 33ed2fcf..8f91cbb1 100644
--- a/spinedb_api/purge.py
+++ b/spinedb_api/purge.py
@@ -10,7 +10,8 @@
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
 
-""" Functions to purge DBs. """
+"""Functions to purge DBs."""
+
 from .db_mapping import DatabaseMapping
 from .exception import NothingToCommit, SpineDBAPIError, SpineDBVersionError
 from .filters.tools import clear_filter_configs
diff --git a/spinedb_api/scenario_recipes.py b/spinedb_api/scenario_recipes.py
index f1cea857..91c5a515 100644
--- a/spinedb_api/scenario_recipes.py
+++ b/spinedb_api/scenario_recipes.py
@@ -94,6 +94,7 @@
 ``coal+coal_chp+wind``, ``coal+coal_chp+antimatter``, ``coal+wind+antimatter``, ``coal_chp+wind+antimatter``
 and ``coal+coal_chp+wind+antimatter``
 """
+
 from collections.abc import Iterable, Sequence
 from spinedb_api import SpineDBAPIError
 from spinedb_api.db_mapping_base import PublicItem
diff --git a/spinedb_api/spine_db_client.py b/spinedb_api/spine_db_client.py
index 61fb81a6..7ebee656 100644
--- a/spinedb_api/spine_db_client.py
+++ b/spinedb_api/spine_db_client.py
@@ -11,6 +11,7 @@
 ######################################################################################################################
 
 """This module defines the :class:`SpineDBClient` class."""
+
 from __future__ import annotations
 from collections.abc import Iterator
 from contextlib import contextmanager
diff --git a/spinedb_api/spine_io/exporters/csv_writer.py b/spinedb_api/spine_io/exporters/csv_writer.py
index e74b7771..3d3a4bf5 100644
--- a/spinedb_api/spine_io/exporters/csv_writer.py
+++ b/spinedb_api/spine_io/exporters/csv_writer.py
@@ -13,6 +13,7 @@
 Module contains a .csv writer implementation.
 
 """
+
 import csv
 import os
 import os.path
diff --git a/spinedb_api/spine_io/exporters/excel.py b/spinedb_api/spine_io/exporters/excel.py
index fa888fd7..96c8fafb 100644
--- a/spinedb_api/spine_io/exporters/excel.py
+++ b/spinedb_api/spine_io/exporters/excel.py
@@ -14,6 +14,7 @@
 Framework for exporting a database to Excel file.
 
 """
+
 from spinedb_api.export_mapping.export_mapping import (
     AlternativeDescriptionMapping,
     AlternativeMapping,
diff --git a/spinedb_api/spine_io/exporters/excel_writer.py b/spinedb_api/spine_io/exporters/excel_writer.py
index 8aacc29a..a0d9e1e9 100644
--- a/spinedb_api/spine_io/exporters/excel_writer.py
+++ b/spinedb_api/spine_io/exporters/excel_writer.py
@@ -14,6 +14,7 @@
 A writer for exporting Spine databases to Excel files.
 
 """
+
 from pathlib import Path
 import re
 import numpy
diff --git a/spinedb_api/spine_io/exporters/gdx_writer.py b/spinedb_api/spine_io/exporters/gdx_writer.py
index 8cdd88bf..d5d3cb05 100644
--- a/spinedb_api/spine_io/exporters/gdx_writer.py
+++ b/spinedb_api/spine_io/exporters/gdx_writer.py
@@ -9,7 +9,8 @@
 # Public License for more details. You should have received a copy of the GNU Lesser General Public License along with
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
-""" Module contains a .gdx writer implementation. """
+"""Module contains a .gdx writer implementation."""
+
 import math
 from gams.core import gdx
 from gdx2py import GAMSParameter, GAMSScalar, GAMSSet, GdxFile
diff --git a/spinedb_api/spine_io/exporters/sql_writer.py b/spinedb_api/spine_io/exporters/sql_writer.py
index 915113d0..bf28ec18 100644
--- a/spinedb_api/spine_io/exporters/sql_writer.py
+++ b/spinedb_api/spine_io/exporters/sql_writer.py
@@ -9,7 +9,8 @@
 # Public License for more details. You should have received a copy of the GNU Lesser General Public License along with
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
-""" Module contains an SQL writer implementation. """
+"""Module contains an SQL writer implementation."""
+
 from sqlalchemy import Boolean, Column, DateTime, Float, Integer, MetaData, String, Table, create_engine
 from sqlalchemy.orm import Session
 from spinedb_api import parameter_value
diff --git a/spinedb_api/spine_io/exporters/writer.py b/spinedb_api/spine_io/exporters/writer.py
index e261ab27..8fe1075e 100644
--- a/spinedb_api/spine_io/exporters/writer.py
+++ b/spinedb_api/spine_io/exporters/writer.py
@@ -9,7 +9,8 @@
 # Public License for more details. You should have received a copy of the GNU Lesser General Public License along with
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
-""" Module contains the :class:`Writer` base class and functions to write tabular data. """
+"""Module contains the :class:`Writer` base class and functions to write tabular data."""
+
 from __future__ import annotations
 from contextlib import contextmanager
 from copy import copy
diff --git a/spinedb_api/spine_io/gdx_utils.py b/spinedb_api/spine_io/gdx_utils.py
index ebe36970..9b8df2b7 100644
--- a/spinedb_api/spine_io/gdx_utils.py
+++ b/spinedb_api/spine_io/gdx_utils.py
@@ -10,7 +10,7 @@
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
 
-""" Utility functions for .gdx import/export. """
+"""Utility functions for .gdx import/export."""
 
 import os
 import re
diff --git a/spinedb_api/spine_io/importers/datapackage_reader.py b/spinedb_api/spine_io/importers/datapackage_reader.py
index 0acb13dc..2df47073 100644
--- a/spinedb_api/spine_io/importers/datapackage_reader.py
+++ b/spinedb_api/spine_io/importers/datapackage_reader.py
@@ -10,7 +10,8 @@
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
 
-""" Contains DataPackageReader class. """
+"""Contains DataPackageReader class."""
+
 from itertools import chain
 import threading
 import frictionless
diff --git a/spinedb_api/spine_io/importers/excel_reader.py b/spinedb_api/spine_io/importers/excel_reader.py
index 506f2041..78bfa7db 100644
--- a/spinedb_api/spine_io/importers/excel_reader.py
+++ b/spinedb_api/spine_io/importers/excel_reader.py
@@ -10,7 +10,7 @@
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
 
-""" Contains ExcelReader class and helper functions. """
+"""Contains ExcelReader class and helper functions."""
 
 import io
 from itertools import chain, islice, takewhile
diff --git a/spinedb_api/spine_io/importers/gdx_reader.py b/spinedb_api/spine_io/importers/gdx_reader.py
index 23478f46..8d70569b 100644
--- a/spinedb_api/spine_io/importers/gdx_reader.py
+++ b/spinedb_api/spine_io/importers/gdx_reader.py
@@ -10,7 +10,8 @@
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
 
-""" Contains GDXReader class and a help function. """
+"""Contains GDXReader class and a help function."""
+
 from gdx2py import GAMSParameter, GAMSScalar, GAMSSet, GdxFile
 from spinedb_api.exception import ReaderError
 from ..gdx_utils import find_gams_directory, gams_supports_new_api
diff --git a/spinedb_api/spine_io/importers/json_reader.py b/spinedb_api/spine_io/importers/json_reader.py
index 5f4031ea..4b12b633 100644
--- a/spinedb_api/spine_io/importers/json_reader.py
+++ b/spinedb_api/spine_io/importers/json_reader.py
@@ -10,7 +10,8 @@
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
 
-""" Contains JSONReader class. """
+"""Contains JSONReader class."""
+
 import itertools
 import os
 import sys
diff --git a/spinedb_api/spine_io/importers/reader.py b/spinedb_api/spine_io/importers/reader.py
index 35830a8a..9c31d1ec 100644
--- a/spinedb_api/spine_io/importers/reader.py
+++ b/spinedb_api/spine_io/importers/reader.py
@@ -10,7 +10,8 @@
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
 
-""" Contains a base class for a data source readers used in importing. """
+"""Contains a base class for a data source readers used in importing."""
+
 from collections.abc import Callable, Iterator
 from dataclasses import dataclass, field
 from itertools import islice
diff --git a/spinedb_api/spine_io/importers/sqlalchemy_reader.py b/spinedb_api/spine_io/importers/sqlalchemy_reader.py
index 41289c83..a3e14478 100644
--- a/spinedb_api/spine_io/importers/sqlalchemy_reader.py
+++ b/spinedb_api/spine_io/importers/sqlalchemy_reader.py
@@ -9,7 +9,8 @@
 # Public License for more details. You should have received a copy of the GNU Lesser General Public License along with
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
-""" Contains SQLAlchemyReader class. """
+"""Contains SQLAlchemyReader class."""
+
 from sqlalchemy import MetaData, create_engine
 from sqlalchemy.orm import Session
 from ...exception import ReaderError
diff --git a/tests/__init__.py b/tests/__init__.py
index 84e68460..6ad86b7c 100644
--- a/tests/__init__.py
+++ b/tests/__init__.py
@@ -10,4 +10,4 @@
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
 
-""" Unit tests package for :mod:`spinedb_api`. """
+"""Unit tests package for :mod:`spinedb_api`."""
diff --git a/tests/export_mapping/test_pivot.py b/tests/export_mapping/test_pivot.py
index 659e0f38..5f2e688b 100644
--- a/tests/export_mapping/test_pivot.py
+++ b/tests/export_mapping/test_pivot.py
@@ -13,6 +13,7 @@
 Contains unit tests for the ``pivot`` module.
 
 """
+
 import unittest
 import numpy
 from spinedb_api.export_mapping.pivot import make_pivot
diff --git a/tests/filters/test_alternative_filter.py b/tests/filters/test_alternative_filter.py
index 9096b504..b274a470 100644
--- a/tests/filters/test_alternative_filter.py
+++ b/tests/filters/test_alternative_filter.py
@@ -9,7 +9,8 @@
 # Public License for more details. You should have received a copy of the GNU Lesser General Public License along with
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
-""" Unit tests for ``alternative_filter`` module. """
+"""Unit tests for ``alternative_filter`` module."""
+
 import gc
 from pathlib import Path
 from tempfile import TemporaryDirectory
diff --git a/tests/filters/test_renamer.py b/tests/filters/test_renamer.py
index 45bd00c0..ab4b0836 100644
--- a/tests/filters/test_renamer.py
+++ b/tests/filters/test_renamer.py
@@ -10,6 +10,7 @@
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
 """Unit tests for ``renamer`` module."""
+
 from pathlib import Path
 from tempfile import TemporaryDirectory
 import unittest
diff --git a/tests/filters/test_scenario_filter.py b/tests/filters/test_scenario_filter.py
index c8ab1e26..87570409 100644
--- a/tests/filters/test_scenario_filter.py
+++ b/tests/filters/test_scenario_filter.py
@@ -9,7 +9,8 @@
 # Public License for more details. You should have received a copy of the GNU Lesser General Public License along with
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
-""" Unit tests for ``alternative_value_filter`` module. """
+"""Unit tests for ``alternative_value_filter`` module."""
+
 from pathlib import Path
 from tempfile import TemporaryDirectory
 import unittest
diff --git a/tests/filters/test_tools.py b/tests/filters/test_tools.py
index 867d937c..13d7d729 100644
--- a/tests/filters/test_tools.py
+++ b/tests/filters/test_tools.py
@@ -9,7 +9,8 @@
 # Public License for more details. You should have received a copy of the GNU Lesser General Public License along with
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
-""" Unit tests for the ``filters.tools`` module. """
+"""Unit tests for the ``filters.tools`` module."""
+
 from datetime import datetime
 import os.path
 from tempfile import TemporaryDirectory
diff --git a/tests/filters/test_value_transformer.py b/tests/filters/test_value_transformer.py
index 03f502fb..d51923b7 100644
--- a/tests/filters/test_value_transformer.py
+++ b/tests/filters/test_value_transformer.py
@@ -10,7 +10,8 @@
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
 
-""" Unit tests for ``value_transformer`` module. """
+"""Unit tests for ``value_transformer`` module."""
+
 from pathlib import Path
 from tempfile import TemporaryDirectory
 import unittest
diff --git a/tests/import_mapping/test_generator.py b/tests/import_mapping/test_generator.py
index 87c69fe7..11da52f0 100644
--- a/tests/import_mapping/test_generator.py
+++ b/tests/import_mapping/test_generator.py
@@ -11,6 +11,7 @@
 ######################################################################################################################
 
 """Contains unit tests for the generator module."""
+
 import unittest
 from spinedb_api import Array, DateTime, Duration, Map
 from spinedb_api.import_mapping.generator import get_mapped_data
diff --git a/tests/import_mapping/test_import_mapping.py b/tests/import_mapping/test_import_mapping.py
index 26c61675..faf318fd 100644
--- a/tests/import_mapping/test_import_mapping.py
+++ b/tests/import_mapping/test_import_mapping.py
@@ -11,6 +11,7 @@
 ######################################################################################################################
 
 """Unit tests for import Mappings."""
+
 import unittest
 from unittest.mock import Mock
 from spinedb_api.exception import InvalidMapping, InvalidMappingComponent
diff --git a/tests/spine_io/exporters/test_csv_writer.py b/tests/spine_io/exporters/test_csv_writer.py
index 076e3f98..f1e6bfa0 100644
--- a/tests/spine_io/exporters/test_csv_writer.py
+++ b/tests/spine_io/exporters/test_csv_writer.py
@@ -10,6 +10,7 @@
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
 """Unit tests for csv writer."""
+
 from pathlib import Path
 from tempfile import TemporaryDirectory
 import unittest
diff --git a/tests/spine_io/exporters/test_excel_writer.py b/tests/spine_io/exporters/test_excel_writer.py
index 3790603e..c58b816c 100644
--- a/tests/spine_io/exporters/test_excel_writer.py
+++ b/tests/spine_io/exporters/test_excel_writer.py
@@ -10,6 +10,7 @@
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
 """Unit tests for Excel writer."""
+
 from itertools import zip_longest
 import os.path
 from tempfile import TemporaryDirectory
diff --git a/tests/spine_io/exporters/test_gdx_writer.py b/tests/spine_io/exporters/test_gdx_writer.py
index ab51a187..916b7173 100644
--- a/tests/spine_io/exporters/test_gdx_writer.py
+++ b/tests/spine_io/exporters/test_gdx_writer.py
@@ -10,6 +10,7 @@
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
 """Unit tests for gdx writer."""
+
 import math
 from pathlib import Path
 import sys
diff --git a/tests/spine_io/exporters/test_sql_writer.py b/tests/spine_io/exporters/test_sql_writer.py
index d728edf5..226229f3 100644
--- a/tests/spine_io/exporters/test_sql_writer.py
+++ b/tests/spine_io/exporters/test_sql_writer.py
@@ -10,6 +10,7 @@
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
 """Unit tests for SQL writer."""
+
 from pathlib import Path
 from tempfile import TemporaryDirectory
 import unittest
diff --git a/tests/spine_io/exporters/test_writer.py b/tests/spine_io/exporters/test_writer.py
index fd9ce5de..4c367169 100644
--- a/tests/spine_io/exporters/test_writer.py
+++ b/tests/spine_io/exporters/test_writer.py
@@ -10,6 +10,7 @@
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
 """Unit tests for ``writer`` module."""
+
 import unittest
 from spinedb_api import DatabaseMapping, import_object_classes, import_objects
 from spinedb_api.export_mapping.settings import entity_export
diff --git a/tests/spine_io/importers/test_json_reader.py b/tests/spine_io/importers/test_json_reader.py
index 710eb98d..8b67e653 100644
--- a/tests/spine_io/importers/test_json_reader.py
+++ b/tests/spine_io/importers/test_json_reader.py
@@ -10,7 +10,8 @@
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
 
-""" Contains unit tests for JSONReader. """
+"""Contains unit tests for JSONReader."""
+
 import json
 from pathlib import Path
 import pickle
diff --git a/tests/test_DatabaseMapping.py b/tests/test_DatabaseMapping.py
index b08de5e6..508b04aa 100644
--- a/tests/test_DatabaseMapping.py
+++ b/tests/test_DatabaseMapping.py
@@ -10,6 +10,7 @@
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
 """Unit tests for DatabaseMapping class."""
+
 from collections import namedtuple
 from datetime import datetime
 import gc
diff --git a/tests/test_arrow_value.py b/tests/test_arrow_value.py
index ee758bfa..09580f32 100644
--- a/tests/test_arrow_value.py
+++ b/tests/test_arrow_value.py
@@ -9,7 +9,8 @@
 # Public License for more details. You should have received a copy of the GNU Lesser General Public License along with
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
-""" Unit tests for the `arrow_value` module. """
+"""Unit tests for the `arrow_value` module."""
+
 import datetime
 import unittest
 import pyarrow
diff --git a/tests/test_db_server.py b/tests/test_db_server.py
index ed4b17fc..5e9cfafe 100644
--- a/tests/test_db_server.py
+++ b/tests/test_db_server.py
@@ -10,6 +10,7 @@
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
 """Unit tests for spine_db_server module."""
+
 import os
 from tempfile import TemporaryDirectory
 import threading
diff --git a/tests/test_export_functions.py b/tests/test_export_functions.py
index c795fd86..4ef752a7 100644
--- a/tests/test_export_functions.py
+++ b/tests/test_export_functions.py
@@ -10,6 +10,7 @@
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
 """Unit tests for export_functions."""
+
 import pathlib
 from tempfile import TemporaryDirectory
 from spinedb_api import (
diff --git a/tests/test_helpers.py b/tests/test_helpers.py
index c132dfcb..c42293fd 100644
--- a/tests/test_helpers.py
+++ b/tests/test_helpers.py
@@ -10,6 +10,7 @@
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
 """Unit tests for helpers.py."""
+
 import gc
 import pathlib
 from tempfile import TemporaryDirectory
diff --git a/tests/test_import_functions.py b/tests/test_import_functions.py
index a256ef1c..7267e2f0 100644
--- a/tests/test_import_functions.py
+++ b/tests/test_import_functions.py
@@ -10,6 +10,7 @@
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
 """Unit tests for import_functions.py."""
+
 import pytest
 from spinedb_api.db_mapping import DatabaseMapping
 from spinedb_api.exception import NothingToCommit
diff --git a/tests/test_migration.py b/tests/test_migration.py
index f02fcbb2..1140c673 100644
--- a/tests/test_migration.py
+++ b/tests/test_migration.py
@@ -10,7 +10,8 @@
 # this program. If not, see <http://www.gnu.org/licenses/>.
 ######################################################################################################################
 
-""" Unit tests for migration scripts. """
+"""Unit tests for migration scripts."""
+
 import os.path
 from tempfile import TemporaryDirectory
 import unittest
diff --git a/tests/test_parameter_value.py b/tests/test_parameter_value.py
index e91db9e5..929e3ea7 100644
--- a/tests/test_parameter_value.py
+++ b/tests/test_parameter_value.py
@@ -11,6 +11,7 @@
 ######################################################################################################################
 
 """Tests for the parameter_value module."""
+
 from datetime import datetime
 import json
 import pickle