---
title: "Configure the Functions Directory"
url: https://docs.catalyst.zoho.com/en/tutorials/todo-list/python/configure-function/
description: "Build a Basic, React, or Angular to-do list web app using Catalyst Advanced I/O Function and Data Store to note down tasks and delete them when done."
last_updated: 2026-11-04T10:10:44Z
service: All Services
type: tutorial
related_links:
  - name: "Advanced I/O Functions"
    url: /en/serverless/help/functions/advanced-io/
  - name: "Functions Directory Structure"
    url: /en/cli/v1/project-directory-structure/functions-directory
---

# Configure the Advanced I/O Function

Next, we will begin coding the to-do list application by configuring the function component.

The [function’s directory](https://docs.catalyst.zoho.com/en/cli/v1/project-directory-structure/functions-directory), `functions/to_do_list_function` contains:

* The `main.py` main function file 

* The `catalyst-config.json` configuration file 

* The `requirements.txt` file to mention any external libraries that you might add.

You will be adding code in the `main.py` file.

The three APIs in the Advanced I/O function that handle the routing between the server and the Data Store are:

* **GET /todo**: To obtain the to-do list items from the *TodoItems* table in the Data Store 

* **POST /todo**: To create and save a new list item in the Data Store 

* **DELETE /todo**: To delete a list item from the Data Store

Next, let’s add the code in the function file. Copy the Python code and paste it in `main.py` in the `functions/to_do_list_function` directory of your project, and save the file. You can use any IDE of your choice to work with the application’s files.

> **Note:** Please go through the code given in this section to ensure you fully understand it. We will discuss the architecture of the function and the client in the next section.

**main.py**

```python
import json
import zcatalyst_sdk
import logging
from flask import Request, make_response, jsonify
logger = logging.getLogger()
def handler(request: Request):
    try:
        app = zcatalyst_sdk.initialize()
        logger = logging.getLogger()
        if request.path == "/add" and request.method == 'POST': 
            req_data = request.get_json()
            notes = req_data.get("notes")           
            table = app.datastore().table('TodoItems')
            row = table.insert_row({
            'Notes': notes
            })
            todo_item = {'id': row['ROWID'], 'notes': notes}        
            response_data = {
                'status': 'success',
                'data': {
                    'todoItem': todo_item
                }
            }
            return make_response(jsonify(response_data), 200)
        elif request.path == "/all" and request.method == 'GET':
            page = request.args.get('page')
            per_page = request.args.get('perPage')
            page = int(page)
            logger.info(page)
            per_page = int(per_page)
            logger.info(per_page)
            zcql_service = app.zcql()     
            row_count = zcql_service.execute_query('SELECT COUNT(ROWID) FROM TodoItems')
            row_id = int(row_count[0]['TodoItems']['COUNT(ROWID)'])
            has_more = int(row_id) > (page) * (per_page)
            logger.info(has_more)
            query_result = zcql_service.execute_query(f'SELECT ROWID, Notes FROM TodoItems LIMIT {(page - 1) * per_page + 1},{per_page}')
            todo_items = [{'id': item['TodoItems']['ROWID'], 'notes': item['TodoItems']['Notes']} for item in query_result]
            get_resp = {
                'status': 'success',
                'data': {
                    'todoItems': todo_items,
                    'hasMore': has_more
                }
            }
            return make_response(jsonify(get_resp), 200)
        elif request.method == 'DELETE':
            row_id = request.path[1:]
            if row_id:
                datastore_service = app.datastore()
                table_service = datastore_service.table("ToDoItems")
                table_service.delete_row(row_id)
                row_response = {
                'status': 'success',
                'data': {
                    'todoItem': {
                        'id': row_id
                    }
                }}         
                logging.info(row_response)
                return make_response(jsonify(row_response), 200)
            else:
                message = {
                'status': 'failure',
                'error': 'Please provide a valid rowid in the request path'
                }
                return make_response(jsonify(message), 400)
        else:
            print('working')
    except Exception as err:
        logger.error(f"Exception in to_do_list_function :{err}")
        response = make_response(jsonify({
                 "error": "Internal server error occurred. Please try again in some time."
        }), 500)
        return response

```

The functions directory is now configured.