Some doubts about the use of parameters into a request toward a REST web service? - spring

Question

I am pretty new in Spring and in REST web services and I have the following dout following a tutorial that show how to implement a RESTful web service using Spring MVC.
So, into a controller class I have this method:
#Controller
#RequestMapping("/api/categories")
public class CategoryRestController {
#RequestMapping
#ResponseBody
public CategoryList getCategories(#RequestParam("start") int start, #RequestParam("size") int size ) {
List<Category> categoryEntries = categoryService.findCategoryEntries(start, size);
return new CategoryList(categoryEntries);
}
}
This method handle HTTP GET request toward the resoruce /api/categories and return the retrieved list into JSON format (I think that it depends by the content negotiazion: if the caller put the Accept header as JSON the method return the result in JSON format, is it right?)
By the way my doubt is related the HTTP request shown in the tutorial, infact it do:
http://localhost:8080/springchocolatestore/api/categories?start=0&size=2
that is handled by the previous controller method to return a paginated list (that could be hude) in JSON format, infact I retrieve the following output:
{
"categories": [
{
"links": [
{
"rel": "self",
"href": "http://localhost:8080/springchocolatestore/api/categories/1",
"variables": [],
"templated": false,
"variableNames": []
}
],
"name": "Truffles",
"description": "Truffles",
"id": {
"rel": "self",
"href": "http://localhost:8080/springchocolatestore/api/categories/1",
"variables": [],
"templated": false,
"variableNames": []
}
},
{
"links": [
{
"rel": "self",
"href": "http://localhost:8080/springchocolatestore/api/categories/2",
"variables": [],
"templated": false,
"variableNames": []
}
],
"name": "Belgian Chocolates",
"description": "Belgian Chocolates",
"id": {
"rel": "self",
"href": "http://localhost:8080/springchocolatestore/api/categories/2",
"variables": [],
"templated": false,
"variableNames": []
}
}
]
}
Ok, so in the request I specify the pagination parameter by categories?start=0&size=2
My doubt is related to the user of this parameter. From what I have understand (but maybe it could be wrong) the use of the parameter is against the RESTful principles. Is it true or am I mising something?
Or maybe in this specific case are valid because the parameter are not specifing an object (that have to be returned into my JSON output) but are only related to some options?
I mean that maybe I can't use parameter to specify a specific object, something like this:
// RETRIEVE THE PRODUCT WITH ID=1
http://localhost:8080/springchocolatestore/api/producs?product=1
So I think that the previous is not following the RESTfull standard because I am specifing a product object with a parameter and not accessing to it as a resource, so I have to do in this way:
http://localhost:8080/springchocolatestore/api/producs/1
Can you give me some clarification?
Tnx

Answer 1

REST doesn't have much to do with URLs, and using request parameters is not unRESTful.
But I agree that path variables are generally used to identify a specific resource, and parameters are generally used for search or pagination parameters.