OpenAI API (ChatGPT) Interaction

This guide demonstrates how to interact with the OpenAI API to use models like GPT-3.5 and GPT-4. It covers setting up the client, sending chat completion requests, and building a simple CLI chatbot.

Modules Used:

openai: The official Python library for the OpenAI API.
python-dotenv: To securely manage the API key.
argparse: To handle command-line arguments.

Prerequisites

OpenAI Account: Sign up at platform.openai.com.
API Key: Create a new secret key in the API keys section.
Credit Balance: Ensure your account has credits (OpenAI API is not free, though new accounts often get trial credits).

Installation

pip install openai python-dotenv

Setup

Create a .env file in your project directory:

OPENAI_API_KEY=sk-your-actual-api-key-here

The Code

Save this as chatgpt_tool.py.

import os
import argparse
from openai import OpenAI
from dotenv import load_dotenv

# 1. Configuration
load_dotenv()
client = OpenAI(api_key=os.getenv("OPENAI_API_KEY"))

def single_query(model, prompt):
    """Send a single prompt and print the response."""
    try:
        response = client.chat.completions.create(
            model=model,
            messages=[
                {"role": "user", "content": prompt}
            ]
        )
        print(response.choices[0].message.content)
    except Exception as e:
        print(f"Error: {e}")

def chat_mode(model):
    """Interactive chat session with history."""
    print(f"--- Chatting with {model} (Type 'quit' to exit) ---")

    # Initialize history with a system message
    history = [
        {"role": "system", "content": "You are a helpful assistant."}
    ]

    while True:
        user_input = input("\nYou: ")
        if user_input.lower() in ['quit', 'exit']:
            break

        if not user_input.strip():
            continue

        # Add user message to history
        history.append({"role": "user", "content": user_input})

        try:
            # Stream response for better UX
            stream = client.chat.completions.create(
                model=model,
                messages=history,
                stream=True,
            )

            print("ChatGPT: ", end="", flush=True)

            collected_response = ""
            for chunk in stream:
                if chunk.choices[0].delta.content is not None:
                    content = chunk.choices[0].delta.content
                    print(content, end="", flush=True)
                    collected_response += content

            print() # Newline

            # Add assistant response to history
            history.append({"role": "assistant", "content": collected_response})

        except Exception as e:
            print(f"\nError: {e}")

if __name__ == "__main__":
    parser = argparse.ArgumentParser(description="OpenAI GPT CLI Tool")
    parser.add_argument("prompt", nargs="?", help="The prompt to send (leave empty for chat mode)")
    parser.add_argument("--model", default="gpt-3.5-turbo", help="Model to use (default: gpt-3.5-turbo)")

    args = parser.parse_args()

    if not os.getenv("OPENAI_API_KEY"):
        print("Error: OPENAI_API_KEY not found in .env file.")
    else:
        if args.prompt:
            single_query(args.model, args.prompt)
        else:
            chat_mode(args.model)

Usage

Interactive Chat:
```
python chatgpt_tool.py
```

Single Prompt:

python chatgpt_tool.py "Write a haiku about Python."

Use GPT-4:
```
python chatgpt_tool.py --model gpt-4
```

programming/python/python

Created: March 17, 2026 • Last Modified: January 28, 2026

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