Making HTTP Get Requests in Python

HTTP GET requests are a way to retrieve data from a server. When you enter a URL into your web browser, your browser sends a GET request to a server to retrieve the content displayed on the page. GET requests are one of the most common types of HTTP requests, and they are used every time you visit a website or click a link.

GET requests are helpful because they are a simple way to retrieve data from a server. They are also easy to use, as they can be made simply by entering a URL into a web browser. Additionally, GET requests can be cached by the browser, which means that if you visit a page multiple times, the content may be loaded from the browser’s cache instead of being retrieved from the server each time. This can help to improve the performance of your web application.

GET requests are also helpful because they can be used to pass data to the server. This is done using query parameters, which are added to the end of the URL. For example, if you want to search for a particular item on a website, you might enter a URL like “example.com/search?query=keyboard”. The “query=keyboard” part of the URL is a query parameter that is passed to the server, which can then use it to search for the desired item.

Options for making Get Requests in Python

There are several options for making HTTP GET requests in Python. The most popular option is to use the requests library, which is a third-party library that is not included with Python by default. The requests library is easy to use and has a lot of features, making it the go-to choice for many Python developers.

import requests 

response = requests.get('https://example.com') 
print(response.text)

In this example, the requests.get() function sends a GET request to the specified URL and returns a Response object. The Response object contains the data that was returned by the server, and you can use the text attribute to access the response as a string.

Another option for making HTTP GET requests in Python is to use the urllib library, which is included with Python by default. The urllib library is a bit more low-level than the requests library, but it can still be used to make GET requests. Here is an example of how to use the urllib.request.urlopen() function to make a GET request:

import urllib.request 

response = urllib.request.urlopen('https://example.com') 
print(response.read())

In this example, the urllib.request.urlopen() function sends a GET request to the specified URL and returns a file-like object. You can use the read() method to read the data that was returned by the server.

Finally, you can also use the httplib library to make HTTP GET requests in Python. The httplib library is a bit more low-level than the other options, and it requires you to create a connection object and manually send the request. Here is an example of how to use the httplib.HTTPConnection() class to make a GET request:

import httplib 

conn = httplib.HTTPConnection('example.com') 
conn.request('GET', '/') response = conn.getresponse() 
print(response.read())

In this example, the httplib.HTTPConnection() class is used to create a connection object, and the request() method is used to send the GET request. The getresponse() method is then used to get the Response object, which contains the data that was returned by the server.

Advanced topics for making HTTP get requests

Here are some advanced concepts that people should know when making HTTP requests in Python:

1. Query parameters: Query parameters are used to pass data to the server as part of a GET request. They are added to the end of the URL, and they are usually used to specify options or to filter data. For example, you might use a query parameter to specify the sort order of a list of items, or to filter a list of items by a particular category.
2. Headers: HTTP headers are used to pass additional information about the request or the response. For example, you might use a header to specify the content type of a request or to set an authentication token. In Python, you can use the headers parameter of the requests.get() function or the add_header() method of the Request object in the urllib library to set headers for a request.
3. Cookies: Cookies are small pieces of data that are stored on the client side and sent to the server with each request. They are often used to store information about the user or to maintain state across multiple requests. In Python, you can use the cookies parameter of the requests.get() function or the CookieJar object in the http.cookiejar module to set cookies for a request.
4. Response codes: HTTP response codes are used to indicate the status of a request. For example, a response code of 200 means that the request was successful, while a response code of 404 means that the requested resource was not found. In Python, you can use the status_code attribute of the Response object in the requests library or the status attribute of the HTTPResponse object in the urllib library to get the response code for a request.
5. Error handling: It’s important to handle errors gracefully when making HTTP requests, as network errors and other issues can occur. In Python, you can use the try and except statements to handle exceptions that might be raised when making a request. For example, you might want to handle a ConnectionError exception if the server is unreachable, or a HTTPError exception if the server returns a non-200 response code.

Setting Query Parameters for Get Requests using the Requests Library

To set query parameters for a GET request using the requests library in Python, you can use the params parameter of the requests.get() function. The params parameter should be a dictionary that contains the query parameters as keys and their values as the corresponding values.

Here is an example of how to set query parameters for a GET request using the requests library:

import requests 

query_params = {'key1': 'value1', 'key2': 'value2'}
 response = requests.get('https://example.com/path', params=query_params)

It’s also possible to set query parameters using the requests.Request object and the requests.Session object. Here is an example of how to do this:

import requests query_params = {'key1': 'value1', 'key2': 'value2'} 
url = 'https://example.com/path' headers = {'User-Agent': 'My User Agent'} 
# Create the Request object 
request = requests.Request('GET', url, params=query_params, headers=headers) 
# Create a Session object and send the request 
session = requests.Session() 
response = session.send(request.prepare())

In this example, the requests.Request object is used to create a request with the specified method, URL, query parameters, and headers. The request.prepare() method is used to create a PreparedRequest object, which can then be sent using the send() method of the Session object. The response object contains the data that was returned by the server.

Setting HTTP Headers for Get Requests using the Requests Library

HTTP headers are used to pass additional information about the request or the response. They can be used to specify the content type of a request, to set an authentication token, or to customize the behavior of the server.

Here is an example of how to set headers for a GET request using the requests library:

import requests 

headers = {'User-Agent': 'My User Agent', 'Accept-Language': 'en-US'} 
response = requests.get('https://example.com/path', headers=headers)

It’s important to note that some headers, such as User-Agent, are commonly used and have a specific meaning. It's a good idea to familiarize yourself with the available HTTP headers and use them appropriately when making requests.

Using Cookies for Get Requests

Cookies are small pieces of data that are stored on the client side and sent to the server with each request. They are often used to store information about the user or to maintain state across multiple requests. For example, a shopping website might use a cookie to store the items that have been added to the user’s shopping cart, or a social media website might use a cookie to store the user’s login status.

Here is an example of how to set cookies for a GET request using the requests library:

import requests 

cookies = {'key1': 'value1', 'key2': 'value2'} 
response = requests.get('https://example.com/path', cookies=cookies)

It’s important to note that cookies are sent with each request to the same domain, so it’s a good idea to be mindful of the data you store in cookies and handle them securely. Additionally, some browsers limit the number and size of cookies that can be stored, so it’s a good idea to minimize the amount of data you store in cookies.

Working with Response codes in the Python Request Library

HTTP response codes are used to indicate the status of a request. They are a three-digit integer that is returned by the server to indicate the result of the request. For example, a response code of 200 means that the request was successful, while a response code of 404 means that the requested resource was not found.

Here is an example of how to get the response code for a GET request using the requests library:

import requests 

response = requests.get('https://example.com/path') 
print(response.status_code)

It’s important to handle response codes appropriately when making HTTP requests. For example, you might want to handle a response code of 404 differently than a response code of 200. You can use the if statement or the try and except statements to handle different response codes in your code.

Error Handing for Get Requests

Error handling is an important aspect of making HTTP requests in Python. It’s important to anticipate and handle errors that might occur when making a request, such as network errors or server errors. By handling errors appropriately, you can prevent your code from crashing and make it more resilient.

Here is an example of how to use the try and except statements to handle errors when making a GET request in Python:

import requests 

url = 'https://example.com/path' 
try: 
  response = requests.get(url) 
except requests.exceptions.ConnectionError: 
  print('There was a connection error') 
except requests.exceptions.HTTPError: 
  print('There was an HTTP error')

Tips for Choosing the Right Python Library for Making Get Requests

It can be difficult to decide which library is the best fit for your project, especially if you are new to Python or to making HTTP requests. Here are a few tips to help you choose the right library to make GET requests in Python:

1. Consider your requirements: Different libraries have different features and capabilities. For example, some libraries might support HTTP/2, while others might not. Some libraries might have a built-in session management, while others might not. Consider what features you need and choose a library that meets your requirements.
2. Evaluate the performance: Some libraries might be faster than others when it comes to making requests. If you are making a lot of requests or if you are working with large amounts of data, it might be worth benchmarking different libraries to see which one performs best.
3. Look at the documentation: A well-written documentation is a sign of a good library. It’s important to choose a library with clear and comprehensive documentation to understand how to use it and get help when you need it.
4. Check the community support: A library with a large and active community is likely to be well-maintained and have more resources available, such as tutorials, examples, and libraries. Consider checking forums, Stack Overflow, or GitHub to see what other people say about the library.
5. Have fun: Don’t take this too seriously! It’s important to choose a library that you enjoy working with. Don’t be afraid to try different libraries and see which one you like best. After all, programming is supposed to be fun, right?

Choosing the right library to make GET requests in Python depends on your specific requirements and preferences. Consider your needs, evaluate the performance, look at the documentation, check the community support, and have fun deciding which library to use. Some popular options include the built-in libraries urllib and httplib, and the third-party library requests.

Now for a humorous anecdote: I once had a colleague who insisted on using the urllib library for everything, no matter how complex the task was. He was convinced that it was the "only true way" to make HTTP requests in Python. One day, we had to make a GET request to an API that required multiple query parameters, authentication, and pagination. My colleague spent hours trying to make it work with urllib, muttering to himself and frantically Googling for solutions. In the end, he threw up his hands in frustration and said, "Fine, I'll use requests like everyone else."

The moral of the story is: sometimes it’s okay to admit that a different library might be a better fit for the task at hand. Don’t be afraid to try out different options and see what works best for you. Happy coding!

Originally published at http://beapython.dev on January 4, 2023.