Merge pull request #58 from pboettch/alembic-integration

Alembic integration

README.rst

@@ -16,17 +16,3 @@ dynamic catalogues (filter-based).
 
 * Free software: GNU General Public License v3
 * Documentation: https://tscat.readthedocs.io.
-
-
-Features
---------
-
-* TODO
-
-Credits
--------
-
-This package was created with Cookiecutter_ and the `audreyr/cookiecutter-pypackage`_ project template.
-
-.. _Cookiecutter: https://github.com/audreyr/cookiecutter
-.. _`audreyr/cookiecutter-pypackage`: https://github.com/audreyr/cookiecutter-pypackage

requirements_dev.txt

@@ -15,6 +15,7 @@ appdirs
 typing_extensions>=3.7
 SQLAlchemy_Utils>=0.37.8
 orjson
+alembic
 appdirs-stubs
 mypy
 pytest-timeout

setup.py

@@ -11,6 +11,7 @@
     history = history_file.read()
 
 requirements = [
+    "alembic",
     "typing_extensions>=3.7",
     'sqlalchemy[mypy]<2',
     "appdirs>=1.4.4 ",

tests/test_db_migration.py

@@ -0,0 +1,27 @@
+import unittest
+import tscat.orm_sqlalchemy
+import os
+import tscat
+import datetime as dt
+
+
+class DBMigration(unittest.TestCase):
+
+    def setUp(self) -> None:
+        if tscat.base._backend:
+            tscat.base._backend.close()
+        test_db_file = os.path.join(os.path.dirname(os.path.realpath(__file__)), 'migration-db-test.sqlite')
+        tscat.base._backend = tscat.orm_sqlalchemy.Backend(testing=test_db_file)
+
+    def test_existing_event_now_has_rating_field(self):
+        existing, = tscat.get_events()
+        self.assertEqual(existing.rating, None)
+
+    def test_creating_event_with_rating(self):
+        tscat.create_event(dt.datetime.now(), dt.datetime.now() + dt.timedelta(days=1), "Patrick", rating=3)
+
+        _, e = tscat.get_events()
+        self.assertEqual(e.author, "Patrick")
+        self.assertEqual(e.rating, 3)
+
+        self.assertEqual(len(tscat.get_events()), 2)

tscat/orm_sqlalchemy/__init__.py

@@ -14,6 +14,7 @@
 
 from sqlalchemy import create_engine, and_, or_, not_, event, func, cast, String
 from sqlalchemy.orm import Session, Query
+from sqlalchemy.pool.base import _ConnectionFairy
 
 from operator import __eq__, __ne__, __ge__, __gt__, __le__, __lt__
 
@@ -126,20 +127,39 @@ def visit_predicate(self, pred: Predicate):
 
 
 class Backend:
-    def __init__(self, testing=False):
-        if testing:
-            url = 'sqlite://'  # memory database
+    def __init__(self, testing: Union[bool, str] = False):
+        if testing is True:
+            sqlite_filename = ""
+        elif isinstance(testing, str):
+            sqlite_filename = 'file:memdb1?mode=memory&cache=shared'  # memory database
+
         else:  # pragma: no cover
             db_file_path = user_data_dir('tscat')
             if not os.path.exists(db_file_path):
                 os.makedirs(db_file_path)
-            url = f'sqlite:///{db_file_path}/backend.sqlite'
+            sqlite_filename = f'{db_file_path}/backend.sqlite'
 
         # self.engine = create_engine(url, echo=True,
-        self.engine = create_engine(url,
+        self.engine = create_engine(f'sqlite:///{sqlite_filename}',
                                     json_serializer=_serialize_json,
                                     json_deserializer=_deserialize_json)
 
+        # copy testing database to memory
+        if isinstance(testing, str):
+            import sqlite3
+            source = sqlite3.connect(testing)
+            assert isinstance(self.engine.raw_connection(), _ConnectionFairy)
+            assert isinstance(self.engine.raw_connection().connection, sqlite3.Connection)  # type: ignore
+            source.backup(self.engine.raw_connection().connection, pages=-1)  # type: ignore
+
+        # tempt alembic migration of the database
+        from alembic.config import Config
+        from alembic import command
+        alembic_cfg = Config(os.path.join(os.path.dirname(__file__), 'alembic.ini'))
+        alembic_cfg.set_main_option("script_location", os.path.join(os.path.dirname(__file__), 'migrations'))
+        alembic_cfg.set_main_option("sqlalchemy.url", f'sqlite:///{sqlite_filename}')
+        command.upgrade(alembic_cfg, "head")
+
         # use BEGIN EXCLUSIVE to lock database exclusively to one process
         @event.listens_for(self.engine, "begin")
         def do_begin(conn):
@@ -149,6 +169,10 @@ def do_begin(conn):
 
         self.session = Session(bind=self.engine, autoflush=True)
 
+    def close(self):
+        self.session.close()
+        self.engine.dispose()
+
     def _specialiced_serialization(self, key, value):
         if key == "predicate":
             return pickle.dumps(value, protocol=3)

tscat/orm_sqlalchemy/alembic.ini

@@ -0,0 +1,116 @@
+# A generic, single database configuration.
+
+[alembic]
+# path to migration scripts
+script_location = migrations
+
+# template used to generate migration file names; The default value is %%(rev)s_%%(slug)s
+# Uncomment the line below if you want the files to be prepended with date and time
+# see https://alembic.sqlalchemy.org/en/latest/tutorial.html#editing-the-ini-file
+# for all available tokens
+# file_template = %%(year)d_%%(month).2d_%%(day).2d_%%(hour).2d%%(minute).2d-%%(rev)s_%%(slug)s
+
+# sys.path path, will be prepended to sys.path if present.
+# defaults to the current working directory.
+prepend_sys_path = .
+
+# timezone to use when rendering the date within the migration file
+# as well as the filename.
+# If specified, requires the python>=3.9 or backports.zoneinfo library.
+# Any required deps can installed by adding `alembic[tz]` to the pip requirements
+# string value is passed to ZoneInfo()
+# leave blank for localtime
+# timezone =
+
+# max length of characters to apply to the
+# "slug" field
+# truncate_slug_length = 40
+
+# set to 'true' to run the environment during
+# the 'revision' command, regardless of autogenerate
+# revision_environment = false
+
+# set to 'true' to allow .pyc and .pyo files without
+# a source .py file to be detected as revisions in the
+# versions/ directory
+# sourceless = false
+
+# version location specification; This defaults
+# to migrations/versions.  When using multiple version
+# directories, initial revisions must be specified with --version-path.
+# The path separator used here should be the separator specified by "version_path_separator" below.
+# version_locations = %(here)s/bar:%(here)s/bat:migrations/versions
+
+# version path separator; As mentioned above, this is the character used to split
+# version_locations. The default within new alembic.ini files is "os", which uses os.pathsep.
+# If this key is omitted entirely, it falls back to the legacy behavior of splitting on spaces and/or commas.
+# Valid values for version_path_separator are:
+#
+# version_path_separator = :
+# version_path_separator = ;
+# version_path_separator = space
+version_path_separator = os  # Use os.pathsep. Default configuration used for new projects.
+
+# set to 'true' to search source files recursively
+# in each "version_locations" directory
+# new in Alembic version 1.10
+# recursive_version_locations = false
+
+# the output encoding used when revision files
+# are written from script.py.mako
+# output_encoding = utf-8
+
+sqlalchemy.url = sqlite:////home/pboettch/.local/share/tscat/backend.sqlite
+
+
+[post_write_hooks]
+# post_write_hooks defines scripts or Python functions that are run
+# on newly generated revision scripts.  See the documentation for further
+# detail and examples
+
+# format using "black" - use the console_scripts runner, against the "black" entrypoint
+# hooks = black
+# black.type = console_scripts
+# black.entrypoint = black
+# black.options = -l 79 REVISION_SCRIPT_FILENAME
+
+# lint with attempts to fix using "ruff" - use the exec runner, execute a binary
+# hooks = ruff
+# ruff.type = exec
+# ruff.executable = %(here)s/.venv/bin/ruff
+# ruff.options = --fix REVISION_SCRIPT_FILENAME
+
+# Logging configuration
+[loggers]
+keys = root,sqlalchemy,alembic
+
+[handlers]
+keys = console
+
+[formatters]
+keys = generic
+
+[logger_root]
+level = WARN
+handlers = console
+qualname =
+
+[logger_sqlalchemy]
+level = WARN
+handlers =
+qualname = sqlalchemy.engine
+
+[logger_alembic]
+level = INFO
+handlers =
+qualname = alembic
+
+[handler_console]
+class = StreamHandler
+args = (sys.stderr,)
+level = NOTSET
+formatter = generic
+
+[formatter_generic]
+format = %(levelname)-5.5s [%(name)s] %(message)s
+datefmt = %H:%M:%S

tscat/orm_sqlalchemy/migrations/README

@@ -0,0 +1,36 @@
+Alembic integration for database migrations
+-------------------------------------------
+
+This library uses alembic for database migrations. Alembic was added
+later on when the database model was already created and used in production.
+
+The goal is to use alembic to create migration scripts that can be used to
+migrate production databases to the current state of the model after an
+upgrade of tscat to a newer version by the user.
+
+Initial steps that were taken starting from the 0.2.0-release (tag ``v0.2.0``):
+
+1. Install alembic with ``pip install alembic``
+2. Go to ``tscat/orm_sqlalchemy``
+3. Create an alembic environment with ``alembic init migrations``. This creates
+   a directory called ``migrations``.
+4. Edit the ``alembic.ini`` file to point to the database URL.
+   As in development we use a sqlite-database in its production location, we need to
+   resolve: e.g. with ``python -c "from appdirs import user_data_dir; print(user_data_dir('tscat'))"``
+   The URL is then the output of the above command with ``backend.sqlite`` appended.
+   As an example: (see the two extra forward slashes after sqlite://)
+
+     ``sqlalchemy.url = sqlite:////home/pboettch/.local/share/tscat/backend.sqlite``
+
+5. Edit the ``env.py`` file to point to the database model.
+6. Remove the database file and create a new one corresponding to the orm of this tscat-version
+7. Create the first migration with ``alembic revision --autogenerate -m "Initial migration"``.
+8. Edit the create migration-script and empty out upgrade and downgrade functions. As we add alembic to
+   an existing production database we do not want to change the database, but only add the migration.
+9. Run the migration with ``alembic upgrade head``. Now alembic should be in sync with the current
+   database model and later migrations are possible.
+
+Steps 7 and 9 are to be repeated when the database model changes.
+
+
+

tscat/orm_sqlalchemy/migrations/env.py

@@ -0,0 +1,77 @@
+from logging.config import fileConfig
+
+from sqlalchemy import engine_from_config
+from sqlalchemy import pool
+
+from alembic import context
+
+# this is the Alembic Config object, which provides
+# access to the values within the .ini file in use.
+config = context.config
+
+# Interpret the config file for Python logging.
+# This line sets up loggers basically.
+if config.config_file_name is not None:
+    fileConfig(config.config_file_name)
+
+# add your model's MetaData object here
+# for 'autogenerate' support
+from tscat.orm_sqlalchemy.orm import Base
+target_metadata = Base.metadata
+
+# other values from the config, defined by the needs of env.py,
+# can be acquired:
+# my_important_option = config.get_main_option("my_important_option")
+# ... etc.
+
+
+def run_migrations_offline() -> None:  # pragma: no cover
+    """Run migrations in 'offline' mode.
+
+    This configures the context with just a URL
+    and not an Engine, though an Engine is acceptable
+    here as well.  By skipping the Engine creation
+    we don't even need a DBAPI to be available.
+
+    Calls to context.execute() here emit the given string to the
+    script output.
+
+    """
+    url = config.get_main_option("sqlalchemy.url")
+    context.configure(
+        url=url,
+        target_metadata=target_metadata,
+        literal_binds=True,
+        dialect_opts={"paramstyle": "named"},
+    )
+
+    with context.begin_transaction():
+        context.run_migrations()
+
+
+def run_migrations_online() -> None:
+    """Run migrations in 'online' mode.
+
+    In this scenario we need to create an Engine
+    and associate a connection with the context.
+
+    """
+    connectable = engine_from_config(
+        config.get_section(config.config_ini_section, {}),
+        prefix="sqlalchemy.",
+        poolclass=pool.NullPool,
+    )
+
+    with connectable.connect() as connection:
+        context.configure(
+            connection=connection, target_metadata=target_metadata
+        )
+
+        with context.begin_transaction():
+            context.run_migrations()
+
+
+if context.is_offline_mode():
+    run_migrations_offline()  # pragma: no cover
+else:
+    run_migrations_online()

tscat/orm_sqlalchemy/migrations/script.py.mako

@@ -0,0 +1,26 @@
+"""${message}
+
+Revision ID: ${up_revision}
+Revises: ${down_revision | comma,n}
+Create Date: ${create_date}
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+${imports if imports else ""}
+
+# revision identifiers, used by Alembic.
+revision: str = ${repr(up_revision)}
+down_revision: Union[str, None] = ${repr(down_revision)}
+branch_labels: Union[str, Sequence[str], None] = ${repr(branch_labels)}
+depends_on: Union[str, Sequence[str], None] = ${repr(depends_on)}
+
+
+def upgrade() -> None:
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade() -> None:
+    ${downgrades if downgrades else "pass"}