GET and POST Requests Using Python

This post discusses two HTTP (Hypertext Transfer Protocol) request methods  GET and POST requests in Python and their implementation in Python. 

What is HTTP? 

HTTP is a set of protocols designed to enable communication between clients and servers. It works as a request-response protocol between a client and a server. A web browser may be the client, and an application on a computer that hosts a website may be the server. So, to request a response from the server, there are mainly two methods:

1. GET: To request data from the server.
2. POST: To submit data to be processed to the server.

Here is a simple diagram that explains the basic concept of GET and POST methods.

 

 Now, to make HTTP requests in Python, we can use several HTTP libraries like:

• httplib
• urllib
• requests

The most elegant and simplest of the above-listed libraries is Requests. We will be using the requests library in this article. To download and install the Requests library, use the following command:

pip install requests

Making a Get request

The above example finds the latitude, longitude, and formatted address of a given location by sending a GET request to the Google Maps API. An API (Application Programming Interface) enables you to access the internal features of a program in a limited fashion. And in most cases, the data provided is in JSON(JavaScript Object Notation) format (which is implemented as dictionary objects in Python!).

Output:

 

Important points to infer:

PARAMS = {'address':location}

The URL for a GET request generally carries some parameters with it. For the requests library, parameters can be defined as a dictionary. These parameters are later parsed down and added to the base URL or the API endpoint. To understand the role of the parameter, try to print r.url after the response object is created. You will see something like this:

http://maps.googleapis.com/maps/api/geocode/json?address=delhi+technological+university

This is the actual URL on which the GET request is made

r = requests.get(url = URL, params = PARAMS)

Here we create a response object ‘r’ which will store the request-response. We use requests.get() method since we are sending a GET request. The two arguments we pass are URL and the parameters dictionary.

data = r.json()

Now, in order to retrieve the data from the response object, we need to convert the raw response content into a JSON-type data structure. This is achieved by using json() method. Finally, we extract the required information by parsing down the JSON-type object.

Making a POST request

This example explains how to paste your source_code to pastebin.com by sending a POST request to the PASTEBIN API. First of all, you will need to generate an API key by signing up here and then accessing your API key here. 

Important features of this code:

data = {'api_dev_key':API_KEY,
        'api_option':'paste',
        'api_paste_code':source_code,
        'api_paste_format':'python'}

Here again, we will need to pass some data to the API server. We store this data as a dictionary.

r = requests.post(url = API_ENDPOINT, data = data)

Here we create a response object ‘r’ which will store the request-response. We use requests.post() method since we are sending a POST request. The two arguments we pass are the URL and the data dictionary.

pastebin_url = r.text

In response, the server processes the data sent to it and sends the pastebin_URL of your source_code which can be simply accessed by r.text.

requests.post method could be used for many other tasks as well like filling and submitting the web forms, posting on your FB timeline using the Facebook Graph API, etc. 

Here are some important points to ponder upon:

• When the method is GET, all form data is encoded into the URL and appended to the action URL as query string parameters. With POST, form data appears within the message body of the HTTP request.
• In the GET method, the parameter data is limited to what we can stuff into the request line (URL). Safest to use less than 2K of parameters, some servers handle up to 64K.No such problem in the POST method since we send data in the message body of the HTTP request, not the URL.
• Only ASCII characters are allowed for data to be sent in the GET method. There is no such restriction in the POST method.
• GET is less secure compared to POST because the data sent is part of the URL. So, the GET method should not be used when sending passwords or other sensitive information.