35 lines
1.0 KiB
Python
35 lines
1.0 KiB
Python
"""Alembic 迁移共享工具（仅用于 versions/ 下的迁移脚本）。"""
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from __future__ import annotations
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import sqlalchemy as sa
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from alembic import op
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def table_exists(table_name: str) -> bool:
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bind = op.get_bind()
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return table_name in sa.inspect(bind).get_table_names()
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def has_column(table_name: str, column_name: str) -> bool:
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if not table_exists(table_name):
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return False
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bind = op.get_bind()
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columns = sa.inspect(bind).get_columns(table_name)
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return any(column["name"] == column_name for column in columns)
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def add_column_if_missing(table_name: str, column: sa.Column) -> bool:
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"""若列不存在则 add_column；返回是否执行了添加。"""
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if has_column(table_name, column.name):
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return False
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op.add_column(table_name, column)
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return True
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def drop_column_if_exists(table_name: str, column_name: str) -> bool:
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if not has_column(table_name, column_name):
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return False
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op.drop_column(table_name, column_name)
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return True
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