Modify app.py to use dicebot#

Open up the app.py file, in the first_function directory to modify the core lambda code.

Add imports to app.py#

First, we'll want to add two import statements to top of app.py to support our bot. Add these lines at line 4, underneath the imports already in place.

import dicebot  # used to import dicebot functionality

from urllib.parse import parse_qs  # used to parse slack input

The dicebot import allows us to handle dice rolling like we did in our interactive shell.

The line from urllib.parse import parse_qs will give us access to the parse_qs library from urllib.parse. That function allows us to parse the slack slash command data from the default value of x-www-form-urlencoded into a python dict.

Update code under lambda_handler function in app.py#

Next, we'll add some modifications to the lambda_handler function in app.py. We will remove all of the default code underneath the considerably huge default docstring, and replace it with the code below. Delete the get_message function as well.

Ensure all code is properly indented throughout! Since this code is underneath the lambda_function each line must have at least 4 spaces before any text.

    dice_input = None

    status_code = 500 # fallback value

    result_output = {} # fallback

    print(event) # ensure event input is logged

    if "body" in event:

        dice_input = event["body"]

    try:

        dice_query = parse_qs(event["body"])

        print(dice_query) # log parsed message from slack

        if "text" in dice_query:

            dice_input = dice_query["text"][0] # The text field is an array

        else:

            dice_input = "" # default to empty string if missing

        parsed_input = dicebot.parse_text(dice_input)

    except Exception as e:

        status_code = 400

        result_output = {"text": str(e)}

    else:

        dice_results = dicebot.roll_dice(**parsed_input)

        print(dice_results)

        result_output = dicebot.format_slack_response(dice_results)

        status_code = 200

    finally:

        return {

            "statusCode": status_code,

            "body": json.dumps(result_output)

        }

Save these changes, and if you are tracking your project in a git repo, go ahead and commit now.

Most of that code is just there for error handling, which we will explain in-depth in chapter 2. The core bot logic works as follows:

• Check that the key body was provided in the event that was passed to the lambda_handler function by API Gateway.