Step 4: Query the tables in a ledger

To query the tables

1. Use the following program (find_vehicles.py) to query all vehicles registered under a person in your ledger.

   3.x

   # Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   # SPDX-License-Identifier: MIT-0
   #
   # Permission is hereby granted, free of charge, to any person obtaining a copy of this
   # software and associated documentation files (the "Software"), to deal in the Software
   # without restriction, including without limitation the rights to use, copy, modify,
   # merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
   # permit persons to whom the Software is furnished to do so.
   #
   # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
   # INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
   # PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   #
   # This code expects that you have AWS credentials setup per:
   # https://boto3.amazonaws.com/v1/documentation/api/latest/guide/quickstart.html
   from logging import basicConfig, getLogger, INFO
   
   from pyqldbsamples.model.sample_data import get_document_ids, print_result, SampleData
   from pyqldbsamples.constants import Constants
   from pyqldbsamples.connect_to_ledger import create_qldb_driver
   
   logger = getLogger(__name__)
   basicConfig(level=INFO)
   
   
   def find_vehicles_for_owner(driver, gov_id):
       """
       Find vehicles registered under a driver using their government ID.
   
       :type driver: :py:class:`pyqldb.driver.qldb_driver.QldbDriver`
       :param driver: An instance of the QldbDriver class.
   
       :type gov_id: str
       :param gov_id: The owner's government ID.
       """
       document_ids = driver.execute_lambda(lambda executor: get_document_ids(executor, Constants.PERSON_TABLE_NAME,
                                                                              'GovId', gov_id))
   
       query = "SELECT Vehicle FROM Vehicle INNER JOIN VehicleRegistration AS r " \
               "ON Vehicle.VIN = r.VIN WHERE r.Owners.PrimaryOwner.PersonId = ?"
   
       for ids in document_ids:
           cursor = driver.execute_lambda(lambda executor: executor.execute_statement(query, ids))
           logger.info('List of Vehicles for owner with GovId: {}...'.format(gov_id))
           print_result(cursor)
   
   
   def main(ledger_name=Constants.LEDGER_NAME):
       """
       Find all vehicles registered under a person.
       """
       try:
           with create_qldb_driver(ledger_name) as driver:
               # Find all vehicles registered under a person.
               gov_id = SampleData.PERSON[0]['GovId']
               find_vehicles_for_owner(driver, gov_id)
       except Exception as e:
           logger.exception('Error getting vehicles for owner.')
           raise e
   
   
   if __name__ == '__main__':
       main()

   2.x

   # Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   # SPDX-License-Identifier: MIT-0
   #
   # Permission is hereby granted, free of charge, to any person obtaining a copy of this
   # software and associated documentation files (the "Software"), to deal in the Software
   # without restriction, including without limitation the rights to use, copy, modify,
   # merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
   # permit persons to whom the Software is furnished to do so.
   #
   # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
   # INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
   # PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
   # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
   # OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
   # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
   #
   # This code expects that you have AWS credentials setup per:
   # https://boto3.amazonaws.com/v1/documentation/api/latest/guide/quickstart.html
   from logging import basicConfig, getLogger, INFO
   
   from pyqldbsamples.model.sample_data import get_document_ids, print_result, SampleData
   from pyqldbsamples.constants import Constants
   from pyqldbsamples.connect_to_ledger import create_qldb_session
   
   logger = getLogger(__name__)
   basicConfig(level=INFO)
   
   
   def find_vehicles_for_owner(transaction_executor, gov_id):
       """
       Find vehicles registered under a driver using their government ID.
   
       :type transaction_executor: :py:class:`pyqldb.execution.executor.Executor`
       :param transaction_executor: An Executor object allowing for execution of statements within a transaction.
   
       :type gov_id: str
       :param gov_id: The owner's government ID.
       """
       document_ids = get_document_ids(transaction_executor, Constants.PERSON_TABLE_NAME, 'GovId', gov_id)
   
       query = "SELECT Vehicle FROM Vehicle INNER JOIN VehicleRegistration AS r " \
               "ON Vehicle.VIN = r.VIN WHERE r.Owners.PrimaryOwner.PersonId = ?"
   
       for ids in document_ids:
           cursor = transaction_executor.execute_statement(query, ids)
           logger.info('List of Vehicles for owner with GovId: {}...'.format(gov_id))
           print_result(cursor)
   
   
   if __name__ == '__main__':
       """
       Find all vehicles registered under a person.
       """
       try:
           with create_qldb_session() as session:
               # Find all vehicles registered under a person.
               gov_id = SampleData.PERSON[0]['GovId']
               session.execute_lambda(lambda executor: find_vehicles_for_owner(executor, gov_id),
                                      lambda retry_attempt: logger.info('Retrying due to OCC conflict...'))
       except Exception:
           logger.exception('Error getting vehicles for owner.')

   Note

   First, this program queries the Person table for the document with GovId LEWISR261LL to get its id metadata field.

   Then, it uses this document id as a foreign key to query the VehicleRegistration table by PrimaryOwner.PersonId. It also joins VehicleRegistration with the Vehicle table on the VIN field.

2. To run the program, enter the following command.

   python find_vehicles.py