json_blob_async.py

# -----------------------------------------------------------------------------
# Copyright (c) 2023, Oracle and/or its affiliates.
#
# This software is dual-licensed to you under the Universal Permissive License
# (UPL) 1.0 as shown at https://oss.oracle.com/licenses/upl and Apache License
# 2.0 as shown at http://www.apache.org/licenses/LICENSE-2.0. You may choose
# either license.
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# If you elect to accept the software under the Apache License, Version 2.0,
# the following applies:
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# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
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#
#    https://www.apache.org/licenses/LICENSE-2.0
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# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# -----------------------------------------------------------------------------

# -----------------------------------------------------------------------------
# json_blob_async.py
#
# An asynchronous version of json_blob.py
#
# Demonstrates how to use a BLOB as a JSON column store.
#
# Note: Oracle Database 12c lets JSON be stored in VARCHAR2 or LOB columns.
#       With Oracle Database 21c using the new JSON type is recommended
#       instead, see json_direct_async.py
#
# Documentation:
#     python-oracledb: https://oracledb.readthedocs.io/en/latest/user_guide/json_data_type.html
#     Oracle Database: https://www.oracle.com/pls/topic/lookup?ctx=dblatest&id=ADJSN
# -----------------------------------------------------------------------------

import asyncio
import json
import sys

import oracledb
import sample_env


async def main():
    connection = await oracledb.connect_async(
        user=sample_env.get_main_user(),
        password=sample_env.get_main_password(),
        dsn=sample_env.get_connect_string(),
    )

    # Minimum database vesion is 12
    db_version = int(connection.version.split(".")[0])
    if db_version < 12:
        sys.exit("This example requires Oracle Database 12.1.0.2 or later")

    # Insert JSON data
    with connection.cursor() as cursor:
        data = dict(name="Rod", dept="Sales", location="Germany")
        inssql = "insert into CustomersAsBlob values (:1, :2)"

        if db_version >= 21:
            # Take advantage of direct binding
            cursor.setinputsizes(None, oracledb.DB_TYPE_JSON)
            await cursor.execute(inssql, [1, data])
        else:
            # Insert the data as a JSON string
            await cursor.execute(inssql, [1, json.dumps(data)])

    # Select JSON data
    with connection.cursor() as cursor:
        sql = "select c.json_data from CustomersAsBlob c"
        await cursor.execute(sql)
        async for (j,) in cursor:
            print(j)

        # Using JSON_VALUE to extract a value from a JSON column

        sql = """select json_value(json_data, '$.location')
                 from CustomersAsBlob
                 offset 0 rows fetch next 1 rows only"""
        await cursor.execute(sql)
        async for (r,) in cursor:
            print(r)

        # Using dot-notation to extract a value from a JSON  (BLOB storage)
        # column

        sql = """select c.json_data.location
                 from CustomersAsBlob c
                 offset 0 rows fetch next 1 rows only"""
        await cursor.execute(sql)
        async for (j,) in cursor:
            print(j)

        # Using JSON_OBJECT to extract relational data as JSON

        sql = """select json_object('key' is d.dummy) dummy
                 from dual d"""
        await cursor.execute(sql)
        async for r in cursor:
            print(r)

        # Using JSON_ARRAYAGG to extract a whole relational table as JSON

        oracledb.defaults.fetch_lobs = False
        sql = """select json_arrayagg(
                            json_object('key' is c.id,
                                        'name' is c.json_data)
                            returning clob)
                 from CustomersAsBlob c"""
        await cursor.execute(sql)
        async for r in cursor:
            print(r)


asyncio.run(main())