Real Python: Python and REST APIs: Interacting With Web Services

There’s an amazing amount of data available on the Web. Many web services, like YouTube and GitHub, make their data accessible to third-party applications through an application programming interface (API). One of the most popular ways to build APIs is the REST architecture style. Python provides some great tools not only to get data from REST APIs but also to build your own Python REST APIs.

In this tutorial, you’ll learn:

• What REST architecture is
• How REST APIs provide access to web data
• How to consume data from REST APIs using the requests library
• What steps to take to build a REST API
• What some popular Python tools are for building REST APIs

By using Python and REST APIs, you can retrieve, parse, update, and manipulate the data provided by any web service you’re interested in.

Free Bonus: Click here to download a copy of the "REST API Examples" Guide and get a hands-on introduction to Python + REST API principles with actionable examples.

REST Architecture

REST stands for representational state transfer and is a software architecture style that defines a pattern for client and server communications over a network. REST provides a set of constraints for software architecture to promote performance, scalability, simplicity, and reliability in the system.

REST defines the following architectural constraints:

• Stateless: The server won’t maintain any state between requests from the client.
• Client-server: The client and server must be decoupled from each other, allowing each to develop independently.
• Cacheable: The data retrieved from the server should be cacheable either by the client or by the server.
• Uniform interface: The server will provide a uniform interface for accessing resources without defining their representation.
• Layered system: The client may access the resources on the server indirectly through other layers such as a proxy or load balancer.
• Code on demand (optional): The server may transfer code to the client that it can run, such as JavaScript for a single-page application.

Note, REST is not a specification but a set of guidelines on how to architect a network-connected software system.

REST APIs and Web Services

A REST web service is any web service that adheres to REST architecture constraints. These web services expose their data to the outside world through an API. REST APIs provide access to web service data through public web URLs.

For example, here’s one of the URLs for GitHub’s REST API:

https://api.github.com/users/<username>

This URL allows you to access information about a specific GitHub user. You access data from a REST API by sending an HTTP request to a specific URL and processing the response.

HTTP Methods

REST APIs listen for HTTP methods like GET, POST, and DELETE to know which operations to perform on the web service’s resources. A resource is any data available in the web service that can be accessed and manipulated with HTTP requests to the REST API. The HTTP method tells the API which action to perform on the resource.

While there are many HTTP methods, the five methods listed below are the most commonly used with REST APIs:

HTTP method	Description
GET	Retrieve an existing resource.
POST	Create a new resource.
PUT	Update an existing resource.
PATCH	Partially update an existing resource.
DELETE	Delete a resource.

A REST API client application can use these five HTTP methods to manage the state of resources in the web service.

Status Codes

Once a REST API receives and processes an HTTP request, it will return an HTTP response. Included in this response is an HTTP status code. This code provides information about the results of the request. An application sending requests to the API can check the status code and perform actions based on the result. These actions could include handling errors or displaying a success message to a user.

Below is a list of the most common status codes returned by REST APIs:

Code	Meaning	Description
200	OK	The requested action was successful.
201	Created	A new resource was created.
202	Accepted	The request was received, but no modification has been made yet.
204	No Content	The request was successful, but the response has no content.
400	Bad Request	The request was malformed.
401	Unauthorized	The client is not authorized to perform the requested action.
404	Not Found	The requested resource was not found.
415	Unsupported Media Type	The request data format is not supported by the server.
422	Unprocessable Entity	The request data was properly formatted but contained invalid or missing data.
500	Internal Server Error	The server threw an error when processing the request.

These ten status codes represent only a small subset of the available HTTP status codes. Status codes are numbered based on the category of the result:

Read the full article at https://realpython.com/api-integration-in-python/ »

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