When Should You Use @QueryParam vs @PathParam in REST APIs?

What are the best practices for using @QueryParam versus @PathParam in REST APIs?

/Vehicle/Car?registration=123
/House/Colonial?region=newengland
@GET
@Path("/employee/{dept}")
Patient getEmployee(@PathParam("dept")Long dept, @QueryParam("id")Long id) ;

In the context of RESTful APIs, `@PathParam` and `@QueryParam` serve different purposes in defining resource paths and parameters. Understanding these distinctions can help you structure your API endpoints more effectively, improving clarity and usability for developers.

@GET
@Path("/employee/{dept}/{id}")
Patient getEmployee(@PathParam("dept") Long dept, @PathParam("id") Long id);

@GET
@Path("/employee")
Patient getEmployee(@QueryParam("dept") Long dept, @QueryParam("id") Long id);

Causes

• `@PathParam` is used for identifying a specific resource within a resource hierarchy.
• `@QueryParam` is used to filter or modify the response based on optional criteria.

Solutions

• Use `@PathParam` to define a clear resource structure that reflects the hierarchy of your application's data model.
• Use `@QueryParam` for optional parameters that influence the response but do not change the resource being addressed.

Mistake: Using @PathParam for optional filtering options that could be represented in the query string.

Solution: Reserve @PathParam for mandatory identifiers directly linked to the resource path, and use @QueryParam for optional filtering.

Mistake: Overcomplicating API routes by putting too much information into the path.

Solution: Keep paths clean and use query parameters for additional filters or options.