Query String Arguments in Flask (and Flask-Smorest)

Query string arguments are a way to pass data to a web server in the form of key-value pairs. In the Flask web framework, query string arguments can be accessed from the request object. This article will discuss how to use query string arguments in Flask, as well as in the Flask-Smorest extension.

Using Query String Arguments in Flask

In Flask, query string arguments are typically used in GET requests. To access query string arguments in a Flask route, you can use the request.args property. For example:

    
@app.route('/hello')
def hello():
    name = request.args.get('name')
    return 'Hello, ' + name
    
  

In this example, the ‘name’ query string argument is accessed using the request.args.get() method. If the client makes a GET request to /hello?name=John, the route will return ‘Hello, John’.

Using Query String Arguments in Flask-Smorest

Flask-Smorest is an extension for Flask that provides features for building RESTful APIs. It includes support for query string validation and parsing. To use query string arguments in Flask-Smorest, you can define query string parameters in the query string decorator.

    
@blp.route('/hello')
@blp.arguments(HelloArgs, location='query')
def hello(args):
    name = args.get('name')
    return 'Hello, ' + name
    
  

In this example, the HelloArgs class defines the expected query string parameters, and the location argument specifies that these parameters should be parsed from the query string. Inside the route function, the query string arguments are accessed using the args.get() method.

Conclusion

Query string arguments are a useful way to pass data to a web server in the form of key-value pairs. In Flask, query string arguments can be accessed from the request object, while Flask-Smorest provides additional features for query string validation and parsing. By understanding how to use query string arguments in Flask and Flask-Smorest, you can build more flexible and powerful web applications.