How to Send POST Requests with Python Requests

When interacting with web services and APIs, being able to send data via HTTP requests is essential. The POST method allows you to submit data to a specified resource, often changing state or producing side effects on the server. Some common use cases for POST requests include submitting HTML forms, posting messages and status updates, and uploading files.

While you can certainly craft raw HTTP requests in Python directly using the built-in http.client and urllib modules, the Requests library provides a much simpler and more human-friendly approach. With an intuitive API and tons of useful features, Requests has become the de facto standard for making HTTP requests in Python. It abstracts away the low-level details, allowing you to focus on the key aspects of the request.

In this tutorial, we‘ll take a closer look at how to send POST requests using Python Requests. We‘ll start with a basic example, then explore how to include various types of data, customize headers, inspect responses, and leverage persistent sessions. Finally, we‘ll touch on some real-world scenarios where posting data with Requests is especially useful. Let‘s dive in!

Sending a Basic POST Request

Before you can use Requests, you‘ll need to install it using pip:

pip install requests

With Requests installed, sending a POST request is incredibly straightforward. Here‘s a minimal example:

import requests

response = requests.post(‘https://httpbin.org/post‘)
print(response.text)

Let‘s break this down:

1. We import the requests module after installing it.
2. The requests.post() function sends an HTTP POST request to the specified URL. We use httpbin, a simple testing service, which echoes back the data we send it.
3. The response from the server is stored in a Response object named response.
4. Finally, we access the content of the response using response.text and print it out.

When you run this code, you should see the response body printed out, which includes the data Requests sent on our behalf. Even in this basic example, Requests has set some default headers, like User-Agent and Accept-Encoding, and negotiated the connection for us.

Including Data in the Request

Of course, the key aspect of a POST request is the data we send to the server. With Requests, you can easily include data in several formats.

To send form-encoded data (like an HTML form submission), simply pass a dictionary to the data parameter:

data = {‘username‘: ‘john‘, ‘password‘: ‘secret‘}
response = requests.post(‘https://httpbin.org/post‘, data=data)

Requests will automatically encode the dictionary as form data and include it in the request body with the appropriate Content-Type header.

If you need to send JSON data, use the json parameter instead:

import json

data = {‘name‘: ‘John Doe‘, ‘age‘: 30}
response = requests.post(‘https://httpbin.org/post‘, json=data)

Requests will serialize the data to JSON and set the Content-Type header to application/json accordingly.

For more control, you can also pass a custom set of headers using the headers parameter:

headers = {‘User-Agent‘: ‘MyCoolApp/1.0‘}  
response = requests.post(‘https://httpbin.org/post‘, headers=headers)

This allows you to override the default headers set by Requests and provide your own as needed.

Inspecting the Response

Once you‘ve sent a POST request, you‘ll want to check the response to ensure it was successful and extract any relevant data. The Response object returned by requests.post() contains all the information you need.

The status_code attribute gives you the HTTP status code of the response:

response = requests.post(‘https://httpbin.org/post‘)
print(response.status_code)  # 200

You can use this to check if the request was successful (2xx status codes) or if there were any errors (4xx or 5xx).

To access the headers sent by the server, use the headers attribute:

print(response.headers[‘Content-Type‘])  # application/json

This is useful for checking the content type, tracking cookies, rate limits, etc.

Finally, to access the actual content of the response, you have a few options:

• response.text gives you the response body as a string
• response.content provides the raw bytes of the response
• response.json() parses the response as JSON and returns a dictionary

For example, if you expect a JSON response, you can extract the data like this:

data = response.json()
print(data[‘origin‘])  # Prints the IP address that made the request

Requests will only raise an exception if there was a network error or the response is not valid JSON.

Using Sessions for Persistent Connections

Sometimes you need to make multiple requests to the same server and want to persist certain parameters across those requests (like cookies, authentication, etc.). Instead of specifying these settings on every request, you can use a Session object.

A Session allows you to persist certain parameters and cookies across requests. Here‘s an example:

session = requests.Session() 
session.headers.update({‘User-Agent‘: ‘MyCoolApp/1.0‘})

# Make a request using the session
response = session.post(‘https://httpbin.org/cookies‘, data={‘foo‘: ‘bar‘})
print(response.text)  # Prints the cookies set by the server

# Make another request using the same session
response = session.get(‘https://httpbin.org/cookies‘)
print(response.text)  # Cookies persist across requests

In this case, we set a custom User-Agent header on the session, which will be sent with every request made using that session. We also make a POST request that sets a cookie, then a GET request that retrieves the same cookie, demonstrating the persistence.

Sessions provide a lot of other functionality too, like automatic cookie handling, authentication management, and more. Definitely check out the Requests documentation on sessions for more details.

Real-World Use Cases

We‘ve looked at the key features of making POST requests with Python Requests, but when might you actually use this in practice? Here are a few common scenarios:

1. Submitting HTML forms: If you‘re scraping a website or automating form submissions, Requests makes it easy to POST form data and handle the response. Just set the data parameter with a dictionary mirroring the form fields.

2. Interacting with web APIs: Many web APIs accept data via POST requests in JSON or XML format. With Requests, you can easily serialize your data and make POST requests to the API endpoints to create or modify resources.

3. Authenticating to web services: When logging into a web service, you often need to submit your credentials via a POST request. You can do this with Requests and then persist the authentication cookies across future requests using a Session.

The great thing about Requests is that it provides a consistent interface regardless of the use case. Once you‘re comfortable with the basic concepts of making POST requests, handling responses, and using sessions, you can adapt that knowledge to any situation involving HTTP interactions.

Conclusion

We‘ve covered a lot of ground in this tutorial, from the basics of making a POST request with Python Requests to handling different types of data, customizing headers, inspecting responses, and leveraging persistent sessions. Hopefully you can see how Requests dramatically simplifies these common tasks compared to using the lower-level HTTP libraries.

One of the reasons Requests has become so popular in the Python ecosystem is its focus on simplicity and readability. The API is designed to be intuitive and concise, allowing you to express complex HTTP interactions with minimal code. Plus, Requests offers advanced features like automatic encoding, redirection handling, connection timeouts, and more, making it robust enough for virtually any production use case.

So next time you need to make HTTP requests in your Python application, whether it‘s a simple REST API client, a web scraper, or an automation tool, give Requests a try. With its elegant API and powerful feature set, it just might become your go-to library for all things HTTP!