Initial Commit

slip slop

migrations/versions/2bd4f3ff0ccc_decouple_musicians.py

@@ -0,0 +1,65 @@
+"""decouple musicians: standalone table, join table for references, fk for learned_from
+
+Revision ID: 2bd4f3ff0ccc
+Revises: ea4bb85f9908
+Create Date: 2026-06-09
+"""
+from alembic import op
+import sqlalchemy as sa
+
+revision = "2bd4f3ff0ccc"
+down_revision = "ea4bb85f9908"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    # 1. Drop the old musicians table (string PK, tied to references)
+    op.drop_table("musicians")
+
+    # 2. Create standalone musicians table with integer PK
+    op.create_table(
+        "musicians",
+        sa.Column("id",   sa.Integer(), primary_key=True, autoincrement=True, nullable=False),
+        sa.Column("name", sa.String(),  nullable=False),
+    )
+
+    # 3. Create reference_musicians join table (many-to-many)
+    op.create_table(
+        "reference_musicians",
+        sa.Column("reference_id", sa.Integer(),
+                  sa.ForeignKey("references.id", ondelete="CASCADE"),
+                  nullable=False),
+        sa.Column("musician_id",  sa.Integer(),
+                  sa.ForeignKey("musicians.id",  ondelete="CASCADE"),
+                  nullable=False),
+        sa.PrimaryKeyConstraint("reference_id", "musician_id"),
+    )
+
+    # 4. Add learned_from_id FK to banjo and fiddle (keep old learned_from text
+    #    column for the downgrade path, then drop it)
+    op.add_column("banjo",  sa.Column("learned_from_id", sa.Integer(),
+                                      sa.ForeignKey("musicians.id", ondelete="SET NULL"),
+                                      nullable=True))
+    op.add_column("fiddle", sa.Column("learned_from_id", sa.Integer(),
+                                      sa.ForeignKey("musicians.id", ondelete="SET NULL"),
+                                      nullable=True))
+    op.drop_column("banjo",  "learned_from")
+    op.drop_column("fiddle", "learned_from")
+
+
+def downgrade() -> None:
+    op.add_column("banjo",  sa.Column("learned_from", sa.String(), nullable=True))
+    op.add_column("fiddle", sa.Column("learned_from", sa.String(), nullable=True))
+    op.drop_column("banjo",  "learned_from_id")
+    op.drop_column("fiddle", "learned_from_id")
+    op.drop_table("reference_musicians")
+    op.drop_table("musicians")
+    # Recreate original musicians table
+    op.create_table(
+        "musicians",
+        sa.Column("name",         sa.String(),  primary_key=True, nullable=False),
+        sa.Column("reference_id", sa.Integer(),
+                  sa.ForeignKey("references.id", ondelete="CASCADE"),
+                  nullable=True),
+    )