REST - Returning Created Object with Spring MVC

问题:

I have a REST call that accepts a JSON object, lets say, a person. After I create this object (validated and saved to the database), I need to return the newly created JSON Object.

I think the standard practice is to return 201 Accepted instead of returning the object immediately. But my application needs the newly created object immediately.

I have a controller methods that takes a POST call, calls a service class, which in turn calls a DAO that uses Hibernate to create the object. Once it's saved to the database, I am calling another controller method that takes the ID of the person and returns the Object.

My question, is this the better approach? That is calling another Controller method to get the newly created object. Or the POST call itself should return the Object.

The main question is: Calling another method takes a round trip and I guess it's an overkill. (Service->DAO->Hibernate->Database). Instead I think I should get the Object from the database immediately after it's saved in the same call (from the method that handled POST).

What is the architecture standard here?

回答1:

Try using ResponseEntity which returns HTTP status along with the object you need.

Sample code is (this was my code where I am returning Customer object, change it as per your needs) :

// imports (for your reference)
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;

// spring controller method
@RequestMapping(value = "getcust/{custid}", method = RequestMethod.GET, produces={"application/json"})
public ResponseEntity<Customer> getToken(@PathVariable("custid") final String custid, HttpServletRequest request) {

    customer = service.getCustById(custid);

    return new ResponseEntity<Customer>(customer, HttpStatus.OK);
}

Read this documentation to know more. Some sample code has been provided there.

回答2:

From the HTTP specification for POST:

If a resource has been created on the origin server, the response SHOULD be 201 (Created) and contain an entity which describes the status of the request and refers to the new resource, and a Location header (see section 14.30).

What you will return in the response body will depend on how strictly you interpret an entity which describes the status of the request and refers to the new resource - and many implementations simply return a representation of the newly created entity itself. The most important thing is to set the Location header in the response to be the URI of the newly created resource, so that clients may immediately fetch it if they so choose.

回答3:

You can return the entity object just after persisting it using @ResponseBody, after @ResponseStatus, but it is not standard, so your client have to be aware about this customization, otherwise if your client depends on standard APIs you have to stuck to the standard by returning void.