Jooby Parameters Overview

Jooby is a micro-framework for building web applications in Java. One of its key features is its robust handling of parameters in HTTP requests. This guide breaks down the main concepts related to parameters in Jooby, providing clarity and practical examples.

Key Concepts

• Parameters: Data sent by the client in requests, which can be received in various ways.
• Types of Parameters:
  • Query Parameters: Data sent in the URL, usually after a question mark (e.g., /search?query=jooby).
  • Path Parameters: Data embedded directly in the URL path (e.g., /user/{id}).
  • Form Parameters: Data sent in the body of a POST request, typically from HTML forms.
  • Header Parameters: Data sent in the HTTP headers.

How to Access Parameters

Jooby provides a simple way to access these parameters within your application. You can use the following methods:

• Query Parameters: Use req.param("name") to retrieve query parameters.
• Path Parameters: Accessed similarly with req.param("id") if defined in the route.
• Form Parameters: Automatically available in the request object during POST.
• Header Parameters: Use req.header("header-name") to get the header value.

Example of Accessing Parameters

get("/search", req -> {
    String query = req.param("query").value();
    return "Searching for: " + query;
});

In this example, when a user accesses /search?query=jooby, the application retrieves the query parameter and responds with the search term.

Validation and Type Conversion

Jooby allows you to validate and convert parameter types easily:

• Validation: Ensure that parameters meet certain criteria before processing them.
• Type Conversion: Jooby automatically converts parameters to the required data type (e.g., converting a string to an integer).

Example of Validation

get("/user/{id}", req -> {
    int userId = req.param("id").intValue();
    // Continue processing with validated userId
});

In this example, the path parameter id is converted to an integer.

Conclusion

Understanding how to work with parameters in Jooby is essential for building interactive web applications. By effectively utilizing query, path, form, and header parameters, you can create dynamic and responsive user experiences. Remember to validate and convert types to ensure your application runs smoothly.