How do you get the Data Received in a Flask Request?

James W.

Problem

You want to access the data passed into your Flask application, but when attempting to access the data using request.data, you found that sometimes the data returned is an empty string that does not represent the data you are trying to access.

Solution

The request module allows you to access the data passed into your Flask application through an HTTP request. The data within a request can be accessed through the request module’s properties. These properties allow for data to be stored in the many different forms that data can be received through HTTP requests, like: query strings, form data, cookies, and more.

The .data property should only be used in circumstances where the data passed into your Flask application comes with a mimetype that Flask does not handle. Otherwise you should use the request property that reflects the type of the data you are trying to access.

Access the right property

Make sure to use the request property that best suits your data.

Here are some request properties for common data types:

• request.arg accesses the query string (the URL parameters) and returns the key/value pairs.

• request.form accesses form data and returns the form parameters (if the form uploads a file however, use request.files to access the file data).

• request.cookies returns a dictionary with the cookies associated with the request.

• request.json returns parsed JSON data if the mimetype is JSON.

Here is a more comprehensive list of request properties.