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Created July 20, 2016 13:00
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How to compile an INSERT ... ON DUPLICATE KEY UPDATE with SQL Alchemy with support for a bulk insert.
#!/usr/bin/env python
# Copyright (c) 2012, Tim Henderson
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
# - Redistributions of source code must retain the above copyright notice,
# this list of conditions and the following disclaimer.
# - Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
# - Neither the name of this software nor the names of its contributors
# may be used to endorse or promote products derived from this software
# without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
# IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
# TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
# PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
# TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
# PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
# LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
# NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
"""
This module provides an "Upsert" statement for SQL Alchemy which uses
ON DUPLICATE KEY UPDATE to implement the insert or update semantics. It
supports doing a bulk insert.
"""
import sqlalchemy as sa
from sqlalchemy.ext.compiler import compiles
class Upsert(expr.Insert): pass
@compiles(Upsert, "mysql")
def compile_upsert(insert_stmt, compiler, **kwargs):
if insert_stmt._has_multi_parameters:
keys = insert_stmt.parameters[0].keys()
else:
keys = insert_stmt.parameters.keys()
pk = insert_stmt.table.primary_key
auto = None
if (len(pk.columns) == 1 and
isinstance(pk.columns.values()[0].type, sa.Integer) and
pk.columns.values()[0].autoincrement):
auto = pk.columns.keys()[0]
if auto in keys:
keys.remove(auto)
insert = compiler.visit_insert(insert_stmt, **kwargs)
ondup = 'ON DUPLICATE KEY UPDATE'
updates = ', '.join(
'%s = VALUES(%s)' % (c.name, c.name)
for c in insert_stmt.table.columns
if c.name in keys
)
if auto is not None:
last_id = '%s = LAST_INSERT_ID(%s)' % (auto, auto)
if updates:
updates = ', '.join((last_id, updates))
else:
updates = last_id
upsert = ' '.join((insert, ondup, updates))
return upsert
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