79 lines
3.0 KiB
Python
79 lines
3.0 KiB
Python
#------------------------------------------------------------------------------
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# Copyright (c) 2016, 2022, Oracle and/or its affiliates.
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#
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# This software is dual-licensed to you under the Universal Permissive License
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# (UPL) 1.0 as shown at https://oss.oracle.com/licenses/upl and Apache License
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# 2.0 as shown at http://www.apache.org/licenses/LICENSE-2.0. You may choose
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# either license.
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#
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# If you elect to accept the software under the Apache License, Version 2.0,
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# the following applies:
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# https://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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#------------------------------------------------------------------------------
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#------------------------------------------------------------------------------
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# subclassing.py
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#
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# Demonstrates how to subclass connections and cursors in order to add
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# additional functionality (like logging) or create specialized interfaces for
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# particular applications.
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#------------------------------------------------------------------------------
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import oracledb
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import sample_env
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# determine whether to use python-oracledb thin mode or thick mode
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if not sample_env.get_is_thin():
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oracledb.init_oracle_client(lib_dir=sample_env.get_oracle_client())
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# sample subclassed Connection which overrides the constructor (so no
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# parameters are required) and the cursor() method (so that the subclassed
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# cursor is returned instead of the default cursor implementation)
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class Connection(oracledb.Connection):
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def __init__(self):
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print("CONNECT", sample_env.get_connect_string())
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super().__init__(user=sample_env.get_main_user(),
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password=sample_env.get_main_password(),
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dsn=sample_env.get_connect_string())
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def cursor(self):
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return Cursor(self)
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# sample subclassed cursor which overrides the execute() and fetchone()
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# methods in order to perform some simple logging
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class Cursor(oracledb.Cursor):
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def execute(self, statement, args):
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print("EXECUTE", statement)
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print("ARGS:")
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for arg_index, arg in enumerate(args):
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print(" ", arg_index + 1, "=>", repr(arg))
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return super().execute(statement, args)
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def fetchone(self):
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print("FETCHONE")
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return super().fetchone()
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# create instances of the subclassed Connection and cursor
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connection = Connection()
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with connection.cursor() as cursor:
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# demonstrate that the subclassed connection and cursor are being used
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cursor.execute("select count(*) from ChildTable where ParentId = :1", (30,))
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count, = cursor.fetchone()
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print("COUNT:", int(count))
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