What is FastAPI – Query Parameters?

Query parameters stand as a formidable asset in bolstering the flexibility and usability of an API. Their utility lies in the ability to filter, sort, paginate, and search data seamlessly, all without the need to create dedicated endpoints for each specific task.

In the FastAPI framework, these optional parameters, aptly named query parameters, can be transmitted to the API endpoint directly through the URL. The mechanism involves including individual parameters after a question mark (?), with each parameter being demarcated by an ampersand (&). This approach not only streamlines the process of interacting with the API but also empowers developers to dynamically tailor their queries, making the API more versatile and user-friendly. There are two main types of query parameters in FastAPI:

• Path parameters: Path parameters are defined in the path to the endpoint, preceded by a question mark (?). They are usually set within curly braces ({}). Path parameters are required to successfully call the endpoint and must be provided in the URL.
• Query string parameters: The query string parameter is defined after the question mark (?) in the endpoint’s query string. They are optional and can be provided if desired.

Why Do We Need Query Parameters?

• Flexibility: The endpoint’s results can be customized to the client’s specific requirements thanks to query parameters. For example, a consumer can restrict product searches by category, price, or rating by using query parameters.
• Usability: Both clients and developers can simply utilize query parameters. Customers may add query parameters to the endpoint’s URL with ease, and developers can verify and validate query parameters within their code very quickly.
• Performance: The number of endpoints that need to be created and updated can be reduced and API speed can be improved with the help of query parameters. For example, instead of setting up separate endpoints for each product category, use a single endpoint with the category query parameter.

Here’s how query parameters can be used in FastAPI:

In this article, we will learn about FastAPI Query Parameters, what are query parameters, what they do in FastAPI, and how to use them. Additionally, we will see examples of query parameters for best practices.