Изменяет обязательность указания предыдущего и следующего модуля при …

…создании нового модуля

backend/migrations/versions/2023_11_18_1723-29ed19cdffbf_.py

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+"""empty message
+
+Revision ID: 29ed19cdffbf
+Revises: b71a5f16b60e
+Create Date: 2023-11-18 17:23:49.682134
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision: str = '29ed19cdffbf'
+down_revision: Union[str, None] = 'b71a5f16b60e'
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.alter_column('modules', 'previous_module_id',
+               existing_type=sa.UUID(),
+               nullable=True)
+    op.alter_column('modules', 'next_module_id',
+               existing_type=sa.UUID(),
+               nullable=True)
+    # ### end Alembic commands ###
+
+
+def downgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.alter_column('modules', 'next_module_id',
+               existing_type=sa.UUID(),
+               nullable=False)
+    op.alter_column('modules', 'previous_module_id',
+               existing_type=sa.UUID(),
+               nullable=False)
+    # ### end Alembic commands ###