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