重载包含不同路径变量类型的 RestController 方法

Question

I have the following problem:

I have a Rest controller that I want to configure in the following URLs:

/api/districts/1,2,3 - (list districts by array of ids)

/api/districts/1 - (list district by a single id)

These are the following mapping methods:

@RequestMapping(value = "/{id}", method = RequestMethod.GET)
public District getById(@PathVariable int id) {
    // check input

    return districtService.getById(id);
}

@RequestMapping(value = "/{districtIDs}", method = RequestMethod.GET)
public List<District> listByArray(@PathVariable Integer[] districtIDs) {
    ArrayList<District> result = new ArrayList<>();

    for (Integer id : districtIDs) {
        result.add(districtService.getById(id));
    }

    return result;
}

This is the error I'm getting when I make a request to /api/districts/1,2,3

There was an unexpected error (type=Internal Server Error, status=500). Ambiguous handler methods mapped for HTTP path 'http://localhost:8080/api/districts/1,2,3': {public java.util.List com.groto.server.web.DistrictsController.listByArray(java.lang.Integer[]), public com.groto.server.models.hibernate.District com.groto.server.web.DistrictsController.getById(int)}

this is the error I'm getting when I make a request to /api/districts/1

There was an unexpected error (type=Internal Server Error, status=500). Ambiguous handler methods mapped for HTTP path 'http://localhost:8080/api/districts/1': {public java.util.List com.groto.server.web.DistrictsController.listByArray(java.lang.Integer[]), public com.groto.server.models.hibernate.District com.groto.server.web.DistrictsController.getById(int)}

Answer 1

In Spring MVC, overloading based on PathVariable type will not be possible, as both the APIs will be considered same. At runtime, two handlers will be found for any of the requests you have mentioned and hence the exception.

You can instead remove the getById() method and the second API will work for a single ID also. Only difference is the return type which will be a List and that can be handled at the client side easily.

Answer 2

I found a solution below url.

https://www.logicbig.com/tutorials/spring-framework/spring-web-mvc/spring-path-variable.html

/**
 * Using mutually exclusive regex, which can be used
 * to avoid ambiguous mapping exception
 */
@Controller
@RequestMapping("/dept")
public class DeptController {

    @RequestMapping("{id:[0-9]+}")
    public String handleRequest(@PathVariable("id") String userId, Model model){
        model.addAttribute("msg", "profile id: "+userId);
        return "my-page";

    }

    @RequestMapping("{name:[a-zA-Z]+}")
    public String handleRequest2 (@PathVariable("name") String deptName, Model model) {
        model.addAttribute("msg", "dept name : " + deptName);
        return "my-page";
    }
}