When to use @QueryParam vs @PathParam

Question

I am not asking the question that is already asked here: What is the difference between @PathParam and @QueryParam

This is a "best practices" or convention question.

When would you use @PathParam vs @QueryParam.

What I can think of that the decision might be using the two to differentiate the information pattern. Let me illustrate below my LTPO - less than perfect observation.

PathParam use could be reserved for information category, which would fall nicely into a branch of an information tree. PathParam could be used to drill down to entity class hierarchy.

Whereas, QueryParam could be reserved for specifying attributes to locate the instance of a class.

For example,

• /Vehicle/Car?registration=123
• /House/Colonial?region=newengland

/category?instance

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

vs /category/instance

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

vs ?category+instance

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

I don't think there is a standard convention of doing it. Is there? However, I would like to hear of how people use PathParam vs QueryParam to differentiate their information like I exemplified above. I would also love to hear the reason behind the practice.

Answer 1

This is what I do.

If there is a scenario to retrieve a record based on id, for example you need to get the details of the employee whose id is 15, then you can have resource with @PathParam.

GET /employee/{id}

If there is a scenario where you need to get the details of all employees but only 10 at a time, you may use query param

GET /employee?start=1&size=10

This says that starting employee id 1 get ten records.

To summarize, use @PathParam for retrieval based on id. User @QueryParam for filter or if you have any fixed list of options that user can pass.