Boto3 DynamoDB client with default table names and serialization/deserialization

pretty_ddb_client.py

import boto3
from boto3.dynamodb.transform import copy_dynamodb_params, TransformationInjector
from boto3.dynamodb.conditions import Attr


def pretty_ddb(*args, default_table_name=None, **kwargs):
    """Builds a DynamoDB client with automatic serialization/deserialization.

    Instead of `.get_item(...) -> {'key': 'S': 'Value', 'count': 'N': '9'}` this
    changes the client to automatically serialize and deserialize as
    `.get_item(...) -> {'key': 'Value', 'count': 9}`

    default_table_name: A default to use if a table name is not passed to
                        operations such as GetItem, Query, etc

    Other args/kwargs are passed to `boto3.client('dynamodb', *args, **kwargs)`

    Implementation is similar to `boto3.dynamodb.transform` and the
    `boto3.resource('dynamodb').meta.client`
    """
    client = boto3.client("dynamodb", *args, **kwargs)
    transformer = TransformationInjector()

    def _set_table_name(params=None, model=None, **kwargs):
        if not params or not model:
            return
        if "TableName" in model.input_shape.required_members:
            if params.get("TableName"):
                # if TableName is already set, skip it
                return
            params["TableName"] = default_table_name
        return params

    if default_table_name:
        client.meta.events.register_first(
            "provide-client-params.dynamodb",
            _set_table_name,
            unique_id="default-table-name",
        )

    client.meta.events.register(
        "provide-client-params.dynamodb",
        copy_dynamodb_params,
        unique_id="dynamodb-create-params-copy",
    )

    # Apply the handler that generates condition expressions including
    # placeholders.
    client.meta.events.register(
        "before-parameter-build.dynamodb",
        transformer.inject_condition_expressions,
        unique_id="dynamodb-condition-expression",
    )

    # Apply the handler that serializes the request from python
    # types to dynamodb types.
    client.meta.events.register(
        "before-parameter-build.dynamodb",
        transformer.inject_attribute_value_input,
        unique_id="dynamodb-attr-value-input",
    )

    # Apply the handler that deserializes the response from dynamodb
    # types to python types.
    client.meta.events.register(
        "after-call.dynamodb",
        transformer.inject_attribute_value_output,
        unique_id="dynamodb-attr-value-output",
    )
    return client


no_default_ddb = pretty_ddb(profile_name="some-profile")
print(
    no_default_ddb.scan(
        TableName="MyTableName",
        FilterExpression=Attr("hash").begins_with("USER#"),
    )["Items"][0]
)
my_ddb = pretty_ddb(default_table_name="MyTableName", region_name="us-east-1")
# calling non-TableName requiring args works normally
my_ddb.list_tables()
# calling a .scan with no TableName still works, and uses the default supplied
print(my_ddb.scan(FilterExpression=Attr("hash").begins_with("USER#"))["Items"][0])