Sending Data with requests.post() & Headers

When creating a new user account, placing a shopping cart order, or submitting a prompt to an AI model like OpenAI or Claude, you use HTTP POST requests to send structured data to the server.

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1. Sending JSON Payloads with json={...}

The requests library provides a built-in json parameter that automatically converts your Python dictionary into a JSON string and sets the Content-Type: application/json header for you:

import requests

url = "https://jsonplaceholder.typicode.com/posts"

# New blog post data to create on server
new_post = {
    "title": "Learning Python in Telugu",
    "body": "Building real AI & Machine Learning applications step by step.",
    "userId": 101
}

# Send the POST request
response = requests.post(url, json=new_post)

print("Status:", response.status_code)  # Output: Status: 201 (Created)
print("Created Data with New ID:", response.json())

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2. Passing Authentication Headers & API Keys

Most production APIs (e.g. OpenAI, Stripe, GitHub, AWS) require you to authenticate yourself by providing an API Key or Bearer Token inside the HTTP Headers:

import requests

api_endpoint = "https://api.example.com/v1/orders"

# Define Custom Headers with your Bearer Token
custom_headers = {
    "Authorization": "Bearer YOUR_SECRET_API_TOKEN_HERE",
    "User-Agent": "ThinkITTeluguApp/1.0",
    "Content-Type": "application/json"
}

order_payload = {
    "product_id": "course_python_ai",
    "amount": 2999
}

response = requests.post(api_endpoint, json=order_payload, headers=custom_headers)

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3. json= vs. data= Parameter

Parameter	Used for	Under the Hood
json={"key": "val"}	Modern REST APIs & JSON	Converts dict to JSON string + sets Content-Type: application/json
data={"username": "sai"}	Traditional HTML Forms	Encodes as application/x-www-form-urlencoded
files={"file": open(...)}	Uploading images & PDFs	Encodes as multipart/form-data

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4. Modifying and Deleting: PUT & DELETE

import requests

# 1. Update post #1 (PUT)
update_payload = {"title": "Updated Title Name"}
put_response = requests.put("https://jsonplaceholder.typicode.com/posts/1", json=update_payload)
print("PUT Status:", put_response.status_code)  # 200

# 2. Delete post #1 (DELETE)
del_response = requests.delete("https://jsonplaceholder.typicode.com/posts/1")
print("DELETE Status:", del_response.status_code)  # 200 (or 204 No Content)

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Quick Summary

• requests.post(url, json=dict): Automatically serializes payloads to JSON format and attaches Content-Type: application/json.
• Headers & Authentication: Pass custom tokens or API keys using headers={"Authorization": "Bearer ..."}.
• Updating & Deleting: requests.put() / requests.patch() modify existing records; requests.delete() removes resources.

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What's Next?

Let's look at production-grade error handling, network timeouts, and status code verification in Handling API Responses & Errors!