simonblanke / sqlite-migrate

A simple database migration system for SQLite, based on sqlite-utils

sqlite-migrate

A simple database migration system for SQLite, based on sqlite-utils.

This project is an early alpha. Expect breaking changes.

Installation

This tool works as a plugin for sqlite-utils. First install that:

pip install sqlite-utils

Then install this plugin like so:

sqlite-utils install sqlite-migrate

Migration files

This tool works against migration files. A migration file looks like this:

from sqlite_migrate import Migrations

# Pick a unique name here - it must not clash with other migration sets that
# the user might run against the same database.

migration = Migrations("creatures")

# Use this decorator against functions that implement migrations
@migration()
def m001_create_table(db):
    # db is a sqlite-utils Database instance
    db["creatures"].create(
        {"id": int, "name": str, "species": str},
        pk="id"
    )

@migration()
def m002_add_weight(db):
    # db is a sqlite-utils Database instance
    db["creatures"].add_column("weight", float)

Here is documentation on the Database instance passed to each migration function.

Running migrations

Running this command will execute those migrations in sequence against the specified database file.

Call migrate with a path to your database and a path to the migrations file you want to apply:

sqlite-utils migrate creatures.db path/to/migrations.py

Running this multiple times will have no additional affect, unless you add more migration functions to the file.

If you call it without arguments it will search for and apply any migrations.py files in the current directory or any of its subdirectories.

You can also pass the path to a directory, in which case all migrations.py files in that directory and its subdirectories will be applied:

sqlite-utils migrate creatures.db path/to/parent/

When applying a single migrations file you can use the --stop-before option to apply all migrations up to but excluding the specified migration:

sqlite-utils migrate creatures.db path/to/migrations.py --stop-before m002_add_weight

Listing migrations

Add --list to list migrations without running them, for example:

sqlite-utils migrate creatures.db --list

The output will look something like this:

Migrations for: creatures

  Applied:
    m001_create_table - 2023-07-23 04:09:40.324002
    m002_add_weight - 2023-07-23 04:09:40.324649
    m003_add_age - 2023-07-23 04:09:44.441616
    m003_cleanup - 2023-07-23 04:09:44.443394
    m004_cleanup - 2023-07-23 04:09:44.444184
    m005_cleanup - 2023-07-23 04:09:44.445389
    m006_cleanup - 2023-07-23 04:09:44.446742
    m007_cleanup - 2023-07-23 04:16:02.529983

  Pending:
    m008_cleanup

Verbose mode

Add -v or --verbose for verbose output, which will show the schema before and after the migrations were applied along with a diff:

sqlite-utils migrate creatures.db --verbose

Example output:

Migrating creatures.db

Schema before:

  CREATE TABLE "_sqlite_migrations" (
     [migration_set] TEXT,
     [name] TEXT,
     [applied_at] TEXT,
     PRIMARY KEY ([migration_set], [name])
  );
  CREATE TABLE [creatures] (
     [id] INTEGER PRIMARY KEY,
     [name] TEXT,
     [species] TEXT
  , [weight] FLOAT);

Schema after:

  CREATE TABLE "_sqlite_migrations" (
     [migration_set] TEXT,
     [name] TEXT,
     [applied_at] TEXT,
     PRIMARY KEY ([migration_set], [name])
  );
  CREATE TABLE "creatures" (
     [id] INTEGER PRIMARY KEY,
     [name] TEXT,
     [species] TEXT,
     [weight] FLOAT,
     [age] INTEGER,
     [shoe_size] INTEGER
  );

Schema diff:

    [applied_at] TEXT,
    PRIMARY KEY ([migration_set], [name])
  );
-CREATE TABLE [creatures] (
+CREATE TABLE "creatures" (
    [id] INTEGER PRIMARY KEY,
    [name] TEXT,
-   [species] TEXT
-, [weight] FLOAT);
+   [species] TEXT,
+   [weight] FLOAT,
+   [age] INTEGER,
+   [shoe_size] INTEGER
+);