Slack Next-gen Platform – Custom Functions

$ slack create
? Select a template to build from:

  Hello World
  A simple workflow that sends a greeting

  Scaffolded project
  A solid foundational project that uses a Slack datastore

> Blank project
  A, well.. blank project

  To see all available samples, visit github.com/slack-samples.

$ cd affectionate-panther-654
$ slack run
? Choose a workspace  seratch  T03E94MJU
   App is not installed to this workspace

Updating dev app install for workspace "Acme Corp"

⚠️  Outgoing domains
   No allowed outgoing domains are configured
   If your function makes network requests, you will need to allow the outgoing domains
   Learn more about upcoming changes to outgoing domains: https://api.slack.com/future/changelog
✨  seratch of Acme Corp
Connected, awaiting events

// -------------------------
// Workflow definition
// -------------------------
import { DefineWorkflow, Schema } from "deno-slack-sdk/mod.ts";
export const workflow = DefineWorkflow({
  callback_id: "custom-function-demo-workflow",
  title: "Custom Function Demo Workflow",
  input_parameters: {
    properties: { channel_id: { type: Schema.slack.types.channel_id } },
    required: ["channel_id"],
  },
});

// Send a message in a channel using the built-in function
workflow.addStep(Schema.slack.functions.SendMessage, {
  channel_id: workflow.inputs.channel_id,
  message: "Hello World!",
});

// -------------------------
// Trigger Definition
// -------------------------
import { Trigger } from "deno-slack-api/types.ts";
const trigger: Trigger<typeof workflow.definition> = {
  type: "shortcut",
  name: "Custom Function Demo Trigger",
  workflow: `#/workflows/${workflow.definition.callback_id}`,
  inputs: { channel_id: { value: "{{data.channel_id}}" } },
};
export default trigger;

import { Manifest } from "deno-slack-sdk/mod.ts";
// Import the workflow you've just created
import { workflow as CustomFunctionDemo } from "./workflow_and_trigger.ts";

export default Manifest({
  name: "affectionate-panther-654",
  description: "Hello World!",
  icon: "assets/default_new_app_icon.png",
  // Add the imported workflow here
  workflows: [CustomFunctionDemo],
  outgoingDomains: [],
  botScopes: ["commands", "chat:write", "chat:write.public"],
});

$ slack triggers create --trigger-def ./workflow_and_trigger.ts
? Choose an app  [Use arrows to move, type to filter]
   seratch  T03E94MJU
   App is not installed to this workspace

>  seratch (dev)  T03E94MJU
   affectionate-panther-654 (dev) A04DHV08MPF

$ slack triggers create --trigger-def ./workflow_and_trigger.ts
? Choose an app  seratch (dev)  T03E94MJU
   affectionate-panther-654 (dev) A04DHV08MPF

⚡ Trigger created
   Trigger ID:   Ft04DEBXXXX
   Trigger Type: shortcut
   Trigger Name: Custom Function Demo Trigger
   URL: https://slack.com/shortcuts/Ft04DEBXXXXX/YYYY

import { DefineFunction, Schema, SlackFunction } from "deno-slack-sdk/mod.ts";
import { FunctionSourceFile } from "https://deno.land/x/deno_slack_source_file_resolver@0.1.5/mod.ts";

export const def = DefineFunction({
  callback_id: "my_send_message",
  title: "My SendMessage",
  source_file: FunctionSourceFile(import.meta.url),
  input_parameters: {
    properties: {
      channel_id: { type: Schema.slack.types.channel_id },
      message: { type: Schema.types.string },
    },
    required: ["channel_id", "message"],
  },
  output_parameters: {
    properties: { ts: { type: Schema.types.string } },
    required: ["ts"],
  },
});

export default SlackFunction(def, async ({ inputs, client }) => {
  const response = await client.chat.postMessage({
    channel: inputs.channel_id,
    text: inputs.message,
  });
  console.log(`chat.postMessage result: ${JSON.stringify(response, null, 2)}`);
  if (response.error) {
    const error = `Failed to post a message due to ${response.error}`;
    return { error };
  }
  return { outputs: { ts: response.ts } };
});

// -------------------------
// Workflow definition
// -------------------------
import { DefineWorkflow, Schema } from "deno-slack-sdk/mod.ts";
export const workflow = DefineWorkflow({
  callback_id: "custom-function-demo-workflow",
  title: "Custom Function Demo Workflow",
  input_parameters: {
    properties: { channel_id: { type: Schema.slack.types.channel_id } },
    required: ["channel_id"],
  },
});

// Replace the built-in function with your own one below
/*
// Send a message in a channel using the built-in function
workflow.addStep(Schema.slack.functions.SendMessage, {
  // Set the channel ID given by trigger -> workflow
  channel_id: workflow.inputs.channel_id,
  message: "Hello World!",
});
*/

// Import your own ./my_send_message.ts and use the function instead
import { def as MySendMessage } from "./my_send_message.ts";
workflow.addStep(MySendMessage, {
  channel_id: workflow.inputs.channel_id,
  message: "Hello World!",
});

chat.postMessage result: {
  "ok": true,
  "channel": "C04FB5UF1C2",
  "ts": "1671685040.050449",
  "message": { ... }
}
2022-12-22 13:57:19 [info] [Fn04G9TKNS91] (Trace=Tr04FVF67P3R) Function execution started for workflow function 'Custom Function Demo Workflow'
2022-12-22 13:57:19 [info] [Wf04GZN08DT2] (Trace=Tr04G9TSDRKM) Executing workflow step 1 of 1
2022-12-22 13:57:19 [info] [Fn04G3DBBWA2] (Trace=Tr04G9TSDRKM) Function execution started for app function 'My SendMessage'
2022-12-22 13:57:20 [info] [Fn04G3DBBWA2] (Trace=Tr04G9TSDRKM) Function execution completed for function 'My SendMessage'
2022-12-22 13:57:21 [info] [Wf04GZN08DT2] (Trace=Tr04G9TSDRKM) Execution completed for workflow step 'My SendMessage'
2022-12-22 13:57:21 [info] [Fn04G9TKNS91] (Trace=Tr04FVF67P3R) Function execution completed for function 'Custom Function Demo Workflow'
2022-12-22 13:57:21 [info] [Wf04GZN08DT2] (Trace=Tr04G9TSDRKM) Execution completed for workflow 'Custom Function Demo Workflow'

import { DefineFunction, Schema, SlackFunction } from "deno-slack-sdk/mod.ts";
import { FunctionSourceFile } from "https://deno.land/x/deno_slack_source_file_resolver@0.1.5/mod.ts";

// Define the metadata of the function:
// No need to be `def`. Any names work for you
export const def = DefineFunction({
  callback_id: "my_send_message",
  title: "My SendMessage",
  // Pass the relative path to this file from the project root directory:
  // If you place this under functions/ directory, the string can be funtions/my_send_message.ts
  // source_file: "my_send_message_with_comments.ts",

  // A 3rd party module "deno_slack_source_file_resolver" automatically resolves the relative path
  source_file: FunctionSourceFile(import.meta.url),

  // Define all the possible inputs with their names and types:
  // Having a description would be helpful for long-term maintenance, but it's optional.
  // You can access the properties inside your function handler code.
  input_parameters: {
    properties: {
      // When setting `Schema.slack.types.channel_id` as the type here,
      // the workflow engine verifies the format of given data.
      // If it's not a channel string, the workflow execution can be terminated as a failure.
      channel_id: { type: Schema.slack.types.channel_id },
      // This general string type accepts any string data,
      message: { type: Schema.types.string },
    },
    // Having the property names ensures they're always available for the handler execution.
    required: ["channel_id", "message"],
  },
  // Define all the possible outputs when the function execution succeeds:
  // When it fails, and you'd like to terminate the workflow execution immediately, your function code should return an error string instead outputs.
  // Otherwise, it's also a good approach to include some error state in outputs,
  // and then let the following functions handle the error outcome.
  output_parameters: {
    properties: { ts: { type: Schema.types.string } },
    // When a property is listed here, your handler code must return the property as part of outputs. TS compiler verifies this for you.
    required: ["ts"],
  },
});

// The default export of the `SlackFunction()` call result is required to make it available for workflows.
// You can pass the above "definition" object as the first argument.
// The second argument is the handler function, which executes the function's logic.
// Also, it must be compatible with the definition's inputs/outputs.
export default SlackFunction(def, async ({
  // All the possible arguments as of this writing
  event, // all the metadata on this function execution event
  inputs, // the properties defined in input_parameters
  env, // we don't use this time, but you can set secrets by slack env command
  team_id, // The connected workspace's ID
  enterprise_id, // The connected Enterprise Grid Org's ID (if that's not the case, this property can be an empty string)
  client, // Slack API client -- if you need direct access to its bot token, you can have `token` as well
}) => {
  // Print everything just to use all the arguments
  console.log(JSON.stringify({ event, inputs, env, team_id, enterprise_id }));
  // Call chat.postMessage API to post a message in a channel
  const response = await client.chat.postMessage({
    channel: inputs.channel_id,
    text: inputs.message,
  });
  console.log(`chat.postMessage result: ${JSON.stringify(response, null, 2)}`);
  if (response.error) {
    // Terminate the workflow execution due to this error
    const error = `Failed to post a message due to ${response.error}`;
    return { error };
  }
  // Return a successful result in the outputs
  return { outputs: { ts: response.ts } };
});