Add some db migrations

README.md

@@ -49,6 +49,14 @@ If you serve the app with a reverse proxy, you should serve the content of
 Bottle webserver.
 
 
+## Updating
+
+If you are updating the app, the database schema may have changed. There is a
+set of migrations under the `migrations` folder which is a set of standalone
+scripts to run to update your database schema. Each script is named after the
+commit it is handling.
+
+
 ## Contributing
 
 All contributions are welcome, feel free to open a MR. Just in case, if you

migrations/d30e5f90530f1d55f236c87aa279920269317047.py

@@ -0,0 +1,51 @@
+import base64
+import os
+
+import magic
+
+from peewee import TextField
+from playhouse.migrate import (
+    SqliteDatabase, SqliteMigrator, migrate
+)
+SCRIPT_DIR = os.path.dirname(__file__)
+
+
+def update_picture(picture):
+    if not picture:
+        return picture
+
+    picture_mime = (
+        'data:%s;base64' % magic.from_buffer(picture,
+                                             mime=True)
+    )
+    return '%s,%s' % (
+        picture_mime,
+        base64.b64encode(picture).decode('utf-8')
+    )
+
+
+def run_migration():
+    recipes_db = SqliteDatabase(os.path.join(SCRIPT_DIR, '../recipes.db'))
+    migrator = SqliteMigrator(recipes_db)
+
+    new_picture_field = TextField(null=True)
+    updated_pictures = [
+        (recipe_id, update_picture(picture))
+        for (recipe_id, picture) in recipes_db.execute_sql(
+            'SELECT id, picture FROM recipe'
+        )
+    ]
+
+    migrate(
+        migrator.drop_column('recipe', 'picture'),
+        migrator.add_column('recipe', 'picture', new_picture_field),
+    )
+
+    for (recipe_id, picture) in updated_pictures:
+        if picture:
+            recipes_db.execute_sql('UPDATE recipe SET picture=? WHERE id=?',
+                                   (picture, recipe_id))
+
+
+if __name__ == "__main__":
+    run_migration()