@RestController avoid declare @RequestBody too [SPR-13868]

[spring-projects-issues]

Manuel Jordan opened SPR-13868 and commented

Hello

I know that @RestController avoid use or declare @ResponseBody
Just curious if is possible apply for @RequestBody too

Perhaps it should be automatically applied to always for the first parameter of the method. Therefore leaving free to declare other parameters.

I mean from

@ResponseStatus(HttpStatus.CREATED)
@RequestMapping(value=PersonaRestControllerSupport.ROOT_URI,
                                method=RequestMethod.POST,
                                consumes={MediaType.APPLICATION_XML_VALUE, MediaType.APPLICATION_JSON_UTF8_VALUE})
public ResponseEntity<Void> saveOne(@Validated @RequestBody Persona persona){

to (No @RequestBody )

@ResponseStatus(HttpStatus.CREATED)
@RequestMapping(value=PersonaRestControllerSupport.ROOT_URI,
                                method=RequestMethod.POST,
                                consumes={MediaType.APPLICATION_XML_VALUE, MediaType.APPLICATION_JSON_UTF8_VALUE})
public ResponseEntity<Void> saveOne(@Validated Persona persona){

In case of many parameters in Rest (Perhaps get the URL, or Header) apply something similar about the following (about Parameter order constrains/restrictions)

public String saveOne(@Validated @ModelAttribute Persona persona,
                                    BindingResult result,
                                    RedirectAttributes redirectAttributes){

Where BindingResult must be located after of the Entity Model.

Thanks

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Affects: 4.2 GA

Issue Links:

• Controller method argument initialized either from the request body or from request parameters [SPR-13742] #18315 Controller method argument initialized either from the request body or from request parameters

[spring-projects-issues]

Rossen Stoyanchev commented

hi Manuel Jordan, currently a controller method argument without annotations (and not handled by any other resolver) is treated in one of two ways. A "simple" parameter type such as String, Number, Date, URI, Locale, etc (as defined by BeanUtils.isSimpleProperty) is treated as a request parameter while any other Object is treated as a command object (i.e. a model attribute) whose properties are bound to request parameters. The @RequestBody annotation then switches those semantics to convert the request body.

I recognize that a lot of REST controllers commonly use the body of the request so flipping the semantics with @RestController does make some sense. For once I'm afraid it's too late to do that at this stage without causing a lot of disruption. Furthermore a @RestController may very well be picking up request parameters (either as a simple type or command object mapped to multiple request parameters) through arguments without annotations. See the discussion under #18315 which shows that a "rest" controller is quite likely to pick up query parameters depending on the Ajax component library you use.

If we did assume @RequestBody by default, we'd have a hard time dealing with "simple" types. It's possible that the intent is to use @RequestBody (since we do have StringHttpMessageConverter and also ObjectToStringHttpMessageConverter backed by a ConversionService) but still it's just as (if not more) likely that you actually want to map to query parameters. So although it does require a little extra effort and space to have @RequestBody I still find it a nice way to express the intent to deserialize the body of the request as opposed to a more natural starting point such as picking up query parameters which are legitimate input in REST interactions too.

[spring-projects-issues]

Manuel Jordan commented

Hi Rossen

Thanks a lot by the detailed explanation.

Seems very interesting the #18315
Now I am watching that post.

To be honest I like use @RequestBody and @ResponseBody, but since @RestController avoids declare one, I thought, why not apply the same approach for other annotation…

-Manuel