Flask Request Object
The Flask Request object represents the HTTP request made by a client to a Flask application.
It contains information about the request, such as the HTTP method used (e.g. GET, POST), the request headers, and the request body.
In this article, you will learn about the Flask Request object and how you can use it to handle requests in your Flask application with examples.
What Is Flask Request Object?
The Flask request object is a part of Flask that has all the details of a request that comes from a client. It has information like the HTTP method used, headers, form data or query parameters submitted, and other details. This object is made using the Request class from Werkzeug library that Flask is based on.
Whenever a client makes a request to a Flask app, the request object is automatically created and filled with the relevant data. Then, you can access this data within your Flask app using the request object.
The request object in Flask has several essential attributes that are presented to you in below table:
| Attributes | Overview |
| Form | It is a collection of key-value pairs that stores form parameters and their associated values. |
| args | This refers to the parsed data of the query string, which is the part of a URL that comes after the question mark symbol (?) and holds key-value pairs. |
| Cookies | This is a dictionary object that stores the names and values of cookies. |
| files | This refers to the information related to a file that has been uploaded, such as its name, size, and content. |
| method | The Request method which is currently in use. |
Creating Request Object In Flask
In Flask, the Request object is automatically created and populated with information about the request when a request is received by the Flask application.
You can access the Request object in your Flask application using the request global variable.
Here’s an example of how to use the request object:
Example:
In above example, the request object is used to retrieve the User-Agent header from the request and return a greeting message that includes the user agent.
Accessing Request Parameters
In addition to the request headers, the Flask Request object also provides easy access to the request parameters.
For example, to access a query parameter in a GET request, you can use the following code:
Example:
In above example, we have used the request.args property to access the query parameters in the request URL and retrieve the value of the “name” parameter.
Handling Request Methods
The Flask Request object also provides information about the HTTP method used in the request.
You can use this information to handle different types of requests differently in your Flask application.
Here’s an example:
Example:
Here, the @app.route decorator specifies that this route only accepts POST requests. The request.get_json() method is then used to retrieve the JSON payload from the request body.
Benefits
The Flask Request Object offers several advantages that make it a valuable tool for web application development:
- The Flask Request Object provides access to various request data, such as form data, query parameters, cookies, and uploaded files. This data can be used for different purposes, such as processing user input, validating form data, and managing file uploads.
- The Flask Request Object is straightforward to use and does not require any setup. It is automatically generated and populated with data when a client sends a request to a Flask application. Therefore, it is easy to access and use request data in your application code.
- The Flask Request Object is flexible and can be customized to fit your specific needs. You can add new attributes to the request object, modify existing ones, or subclass the request object to create a custom request object that fits your requirements.
- The Flask Request Object makes it simple to test your application code. You can create mock requests with specific request data to simulate different scenarios and test the behavior of your application code.
- The Flask Request Object provides various security features such as automatic escaping of HTML and XML entities to prevent XSS attacks, built-in support for CSRF protection, and support for secure cookies.
Where You Should Use Flask Request Object?
So, where should you use the Flask Request object in your Flask application? The answer is: almost everywhere! Whenever you need to handle incoming requests, whether it’s to access user input, retrieve data from a database, or handle API calls, the Flask Request object is your go-to tool.
Here are some examples of where you might use the Flask Request object in your Flask application:
- Building a simple form-based application that allows users to submit data.
- Creating an API endpoint that accepts POST requests with JSON payloads.
- Building a web scraper that retrieves data from a remote server and returns it as a response to an HTTP request.
- Implementing a custom authentication mechanism that checks for a specific header in the request.
Conclusion
The Flask Request Object is a useful tool for creating web applications using Flask. It allows developers to easily access a variety of request data, making it easy to manage user input and file uploads. Additionally, the Flask Request Object is highly adaptable, allowing developers to add their own attributes or create a custom request object. It also provides built-in security features to protect against common web threats like XSS and CSRF attacks. Overall, the Flask Request Object makes it easier to handle incoming requests and enhances the security and functionality of web applications.
