forked from openlp/openlp
73 lines
3.0 KiB
Python
73 lines
3.0 KiB
Python
# -*- coding: utf-8 -*-
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# vim: autoindent shiftwidth=4 expandtab textwidth=120 tabstop=4 softtabstop=4
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###############################################################################
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# OpenLP - Open Source Lyrics Projection #
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# --------------------------------------------------------------------------- #
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# Copyright (c) 2008-2019 OpenLP Developers #
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# --------------------------------------------------------------------------- #
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# This program is free software; you can redistribute it and/or modify it #
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# under the terms of the GNU General Public License as published by the Free #
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# Software Foundation; version 2 of the License. #
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# #
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# This program is distributed in the hope that it will be useful, but WITHOUT #
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# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or #
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# FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for #
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# more details. #
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# #
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# You should have received a copy of the GNU General Public License along #
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# with this program; if not, write to the Free Software Foundation, Inc., 59 #
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# Temple Place, Suite 330, Boston, MA 02111-1307 USA #
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###############################################################################
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"""
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The :mod:`db` module provides helper functions for database related methods.
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"""
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import logging
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from copy import deepcopy
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import sqlalchemy
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log = logging.getLogger(__name__)
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def drop_column(op, tablename, columnname):
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drop_columns(op, tablename, [columnname])
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def drop_columns(op, tablename, columns):
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"""
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Column dropping functionality for SQLite, as there is no DROP COLUMN support in SQLite
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From https://github.com/klugjohannes/alembic-sqlite
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"""
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# get the db engine and reflect database tables
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engine = op.get_bind()
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meta = sqlalchemy.MetaData(bind=engine)
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meta.reflect()
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# create a select statement from the old table
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old_table = meta.tables[tablename]
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select = sqlalchemy.sql.select([c for c in old_table.c if c.name not in columns])
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# get remaining columns without table attribute attached
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remaining_columns = [deepcopy(c) for c in old_table.columns if c.name not in columns]
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for column in remaining_columns:
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column.table = None
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# create a temporary new table
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new_tablename = '{0}_new'.format(tablename)
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op.create_table(new_tablename, *remaining_columns)
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meta.reflect()
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new_table = meta.tables[new_tablename]
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# copy data from old table
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insert = sqlalchemy.sql.insert(new_table).from_select([c.name for c in remaining_columns], select)
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engine.execute(insert)
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# drop the old table and rename the new table to take the old tables
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# position
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op.drop_table(tablename)
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op.rename_table(new_tablename, tablename)
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