Add Alembiс for db migrations

[Roc25]

For #561

Migrations should be created and applied automatically when user opens library

[Roc25]

Currently, every time the library is opened, a empty migration file is created. And at this moment I don't know how to to avoid creating empty migration files and leave them to be created automatically. Only way that i see is manual addition of migration files by developers (I'm not expert here, so i think it may cause errors)

Need help

[yedpodtrzitko]

see this commit addressing some issues mentioned
yedpodtrzitko@17e2df1

• migrations/versions/* shouldnt be in .gitignore because we actually need to keep the generated migrations inside repository

• there's a problem with alembic.ini location. it's outside the tagstudio folder, which assumes the alembic import statements should start with tagstudio. Howver in env.py, you use import starting with src. (subfolder of tagstudio), which implies that alembic is executed from within the tagstudio folder... but that doesnt actually match the content of alembic.ini. So either the imports need to change, or the content (and ideally location) of alembic.ini needs to be inside tagstudio. In the commit above I changed content of alembic.ini.

• to generate the migrations, there needs to be some database to compare its content with the models to generate the difference for migrations. I added an empty database file into the alembic folder and assigned its path to sqlachemy.url in alembic.ini

• after that it's possible to generate the initial migration via:

# inside `tagstudio` folder
alembic -c ../alembic.ini revision --autogenerate -m "initial migration"

[Roc25]

I am very grateful for your help. As far as I understand, if someone changes the models, they will have to create a migration file.

I will remove the automatic creation of migration files and test how everything works now

[Roc25]

If I understand you correctly, we can also not change imports and not move alembic.ini, but we can add /tagstudio to sys.path

In alembic.ini
prepend_sys_path = . tagstudio

In that way we can use alembic in root dir and imports will be ok. If I missed something let me know

[yedpodtrzitko]

it doesnt work for me. When I try to run TS from your branch and open a library, I end up with this error:

Traceback (most recent call last):
  File "/Users/yed/dev/python/TagStudio/tagstudio/src/qt/widgets/preview_panel.py", line 374, in <lambda>
    return lambda: self.driver.open_library(Path(path))
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/yed/dev/python/TagStudio/tagstudio/src/qt/ts_qt.py", line 1118, in open_library
    open_status = self.lib.open_library(path)
                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/yed/dev/python/TagStudio/tagstudio/src/core/library/alchemy/library.py", line 170, in open_library
    self.migrate(connection_string.render_as_string(hide_password=False))
  File "/Users/yed/dev/python/TagStudio/tagstudio/src/core/library/alchemy/library.py", line 147, in migrate
    command.stamp(alembic_cfg, "head")
  File "/Users/yed/.pyenv/versions/312-tags/lib/python3.12/site-packages/alembic/command.py", line 665, in stamp
    script = ScriptDirectory.from_config(config)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/yed/.pyenv/versions/312-tags/lib/python3.12/site-packages/alembic/script/base.py", line 170, in from_config
    raise util.CommandError(
alembic.util.exc.CommandError: No 'script_location' key found in configuration.