Accessing Query String in Flask Routes

When working with Flask, it's essential to be able to access query parameters and the query string in your routes to handle user input and process data effectively. Let's explore how to do just that.

Consider the following example route:

@app.route("/data")
def data():
    # query_string = ???
    return render_template("data.html")

In this scenario, how can we access the query string if a request like example.com/data?abc=123 is made? We want to retrieve either the entire query string (?abc=123) or specific parameter values, such as abc.

To achieve this, we can utilize Flask's request object. Specifically, the args attribute of this object provides access to the request's query parameters. Here's how you can do it:

from flask import request

@app.route('/data')
def data():
    # Here we want to get the value of 'user' (i.e. ?user=some-value)
    user = request.args.get('user')

Using request.args.get('parameter_name'), you can access the value of a specific query parameter. In the example above, we retrieve the value of the 'user' parameter if present in the query string.

This approach now provides you with convenient access to query parameters and the entire query string within your Flask routes, empowering you to handle user input and process data effectively in your application.