def usage_demo()

in python/example_code/dynamodb/batching/dynamo_batching.py [0:0]

• 74 lines of code
• 14 McCabe index (conditional complexity)

def usage_demo():
    """
    Shows how to use the Amazon DynamoDB batch functions.
    """
    logging.basicConfig(level=logging.INFO, format='%(levelname)s: %(message)s')

    print('-'*88)
    print("Welcome to the Amazon DynamoDB batch usage demo.")
    print('-'*88)

    movies_file_name = 'moviedata.json'
    print(f"Getting movie data from {movies_file_name}.")
    try:
        with open(movies_file_name) as json_file:
            movie_data = json.load(json_file, parse_float=decimal.Decimal)
            movie_data = movie_data[:500]  # Only use the first 500 movies for the demo.
    except FileNotFoundError:
        print(f"The file moviedata.json was not found in the current working directory "
              f"{os.getcwd()}.\n"
              f"1. Download the zip file from https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/samples/moviedata.zip.\n"
              f"2. Extract '{movies_file_name}' to {os.getcwd()}.\n"
              f"3. Run the usage demo again.")
        return

    # Build a second table centered around actors.
    actor_set = {}
    for movie in movie_data:
        try:
            actors = movie['info']['actors']
            for actor in actors:
                if actor not in actor_set:
                    actor_set[actor] = {'directors': set(), 'costars': set()}
                actor_set[actor]['directors'].update(movie['info']['directors'])
                actor_set[actor]['costars'].update([a for a in actors if a != actor])
        except KeyError:
            logger.warning("%s doesn't have any actors.", movie['title'])
    actor_data = []
    for key, value in actor_set.items():
        actor_item = {'name': key}
        if len(value['directors']) > 0:
            actor_item['directors'] = value['directors']
        if len(value['costars']) > 0:
            actor_item['costars'] = value['costars']
        actor_data.append(actor_item)

    movie_schema = [
        {'name': 'year', 'key_type': 'HASH', 'type': 'N'},
        {'name': 'title', 'key_type': 'RANGE', 'type': 'S'}
    ]
    actor_schema = [
        {'name': 'name', 'key_type': 'HASH', 'type': 'S'},
    ]

    print(f"Creating movie and actor tables and waiting until they exist...")
    movie_table = create_table(f'demo-batch-movies-{time.time_ns()}', movie_schema)
    actor_table = create_table(f'demo-batch-actors-{time.time_ns()}', actor_schema)
    print(f"Created {movie_table.name} and {actor_table.name}.")

    print(f"Putting {len(movie_data)} movies into {movie_table.name}.")
    fill_table(movie_table, movie_data)

    print(f"Putting {len(actor_data)} actors into {actor_table.name}.")
    fill_table(actor_table, actor_data)

    movie_list = [(movie['year'], movie['title'])
                  for movie in movie_data[0:int(MAX_GET_SIZE/2)]]
    actor_list = [actor['name']
                  for actor in actor_data[0:int(MAX_GET_SIZE/2)]]
    items = get_batch_data(movie_table, movie_list, actor_table, actor_list)
    print(f"Got {len(items[movie_table.name])} movies from {movie_table.name}\n"
          f"and {len(items[actor_table.name])} actors from {actor_table.name}.")
    print("The first 2 movies returned are: ")
    pprint.pprint(items[movie_table.name][:2])
    print(f"The first 2 actors returned are: ")
    pprint.pprint(items[actor_table.name][:2])

    print(
        "Archiving the first 10 movies by creating a table to store archived "
        "movies and deleting them from the main movie table.")
    # Duplicate the movies in the list to demonstrate how the batch writer can be
    # configured to remove duplicate requests from the batch.
    movie_list = movie_data[0:10] + movie_data[0:10]
    archive_table = archive_movies(movie_table, movie_list)
    print(f"Movies successfully archived to {archive_table.name}.")

    archive_table.delete()
    movie_table.delete()
    actor_table.delete()
    print(f"Deleted {movie_table.name}, {archive_table.name}, and {actor_table.name}.")
    print("Thanks for watching!")