Custom adapters

Adapters are flexible and can be adjusted based on the framework you prefer. There are two necessary components of adapters:

• __init__(app: App): Constructor that accepts and stores an instance of the Bolt App.
• handle(req: Request): Function (typically named handle()) that receives incoming Slack requests, parses them to conform to an instance of BoltRequest, then dispatches them to the stored Bolt app.

BoltRequest instantiation accepts four parameters:

Parameter	Description	Required?
body: str	The raw request body	Yes
query: any	The query string data	No
headers: Dict[str, Union[str, List[str]]]	Request headers	No
context: BoltContext	Any context for the request	No

Your adapter will return an instance of BoltResponse from the Bolt app.

For more in-depth examples of custom adapters, look at the implementations of the built-in adapters.

# Necessary imports for Flask
from flask import Request, Response, make_response

from slack_bolt.app import App
from slack_bolt.request import BoltRequest
from slack_bolt.response import BoltResponse

# This example is a simplified version of the Flask adapter
# For a more detailed, complete example, look in the adapter folder
# github.com/slackapi/bolt-python/blob/main/slack_bolt/adapter/flask/handler.py

# Takes in an HTTP request and converts it to a standard BoltRequest
def to_bolt_request(req: Request) -> BoltRequest:
    return BoltRequest(
        body=req.get_data(as_text=True),
        query=req.query_string.decode("utf-8"),
        headers=req.headers,
    )

# Takes in a BoltResponse and converts it to a standard Flask response
def to_flask_response(bolt_resp: BoltResponse) -> Response:
    resp: Response = make_response(bolt_resp.body, bolt_resp.status)
    for k, values in bolt_resp.headers.items():
        for v in values:
            resp.headers.add_header(k, v)
    return resp

# Instantiated from your app
# Accepts a Flask app
class SlackRequestHandler:
    def __init__(self, app: App):
        self.app = app

    # handle() will be called from your Flask app 
    # when you receive a request from Slack
    def handle(self, req: Request) -> Response:
        # This example does not cover OAuth
        if req.method == "POST":
            # Dispatch the request for Bolt to handle and route
            bolt_resp: BoltResponse = self.app.dispatch(to_bolt_request(req))
            return to_flask_response(bolt_resp)

        return make_response("Not Found", 404)