conversations.list

import com.slack.api.Slack;
import com.slack.api.methods.SlackApiException;
import com.slack.api.model.Conversation;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.util.List;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

public class ConversationsList {

    static final ConcurrentMap<String, Conversation> conversationsStore = new ConcurrentHashMap<>();

    /**
     * Fetch conversations using the conversations.list method
     */
    static void fetchConversations() {
        // you can get this instance via ctx.client() in a Bolt app
        var client = Slack.getInstance().methods();
        var logger = LoggerFactory.getLogger("my-awesome-slack-app");
        try {
            // Call the conversations.list method using the built-in WebClient
            var result = client.conversationsList(r -> r
                // The token you used to initialize your app
                .token(System.getenv("SLACK_BOT_TOKEN"))
            );
            saveConversations(result.getChannels());
        } catch (IOException | SlackApiException e) {
            logger.error("error: {}", e.getMessage(), e);
        }
    }

    /**
     * Put conversations into an object
     */
    static void saveConversations(List<Conversation> conversations) {
        for (Conversation conversation : conversations) {
            conversationsStore.put(conversation.getId(), conversation);
        }
    }

    public static void main(String[] args) throws Exception {
        fetchConversations();
    }

}

Hide code to initialize app
// Require the Node Slack SDK package (github.com/slackapi/node-slack-sdk)
const { WebClient, LogLevel } = require("@slack/web-api");

// WebClient insantiates a client that can call API methods
// When using Bolt, you can use either `app.client` or the `client` passed to listeners.
const client = new WebClient("xoxb-your-token", {
  // LogLevel can be imported and used to make debugging simpler
  logLevel: LogLevel.DEBUG
});
Show code to initialize app
// You probably want to use a database to store any conversations information ;)
let conversationsStore = {};

async function populateConversationStore() {
  try {
    // Call the conversations.list method using the WebClient
    const result = await client.conversations.list();

    saveConversations(result.channels);
  }
  catch (error) {
    console.error(error);
  }
}

// Put conversations into the JavaScript object
function saveConversations(conversationsArray) {
  let conversationId = '';
  
  conversationsArray.forEach(function(conversation){
    // Key conversation info on its unique ID
    conversationId = conversation["id"];
    
    // Store the entire conversation object (you may not need all of the info)
    conversationsStore[conversationId] = conversation;
  });
}

populateConversationStore();

Hide code to initialize app
import os
# Import WebClient from Python SDK (github.com/slackapi/python-slack-sdk)
from slack_sdk import WebClient
from slack_sdk.errors import SlackApiError

# WebClient insantiates a client that can call API methods
# When using Bolt, you can use either `app.client` or the `client` passed to listeners.
client = WebClient(token=os.environ.get("SLACK_BOT_TOKEN"))
Show code to initialize app
# You probably want to use a database to store any conversations information ;)
conversations_store = {}

def fetch_conversations():
    try:
        # Call the conversations.list method using the WebClient
        result = client.conversations_list()
        save_conversations(result["channels"])

    except SlackApiError as e:
        logger.error("Error fetching conversations: {}".format(e))


# Put conversations into the JavaScript object
def save_conversations(conversations):
    conversation_id = ""
    for conversation in conversations:
        # Key conversation info on its unique ID
        conversation_id = conversation["id"]

        # Store the entire conversation object
        # (you may not need all of the info)
        conversations_store[conversation_id] = conversation

fetch_conversations()