Can I use @Requestparam annotation for a Post request?

问题

I have this controller method:

@PostMapping(
        value = "/createleave",
        params = {"start","end","hours","username"})
public void createLeave(@RequestParam(value = "start") String start,
                        @RequestParam(value = "end") String end,
                        @RequestParam(value = "hours") String hours,
                        @RequestParam(value = "username") String username){
    System.out.println("Entering createLeave " + start + " " + end + " " + hours + " " + username);
    LeaveQuery newLeaveQuery = new LeaveQuery();
    Account account = accountRepository.findByUsername(username);
    newLeaveQuery.setAccount(account);
    newLeaveQuery.setStartDate(new Date(Long.parseLong(start)));
    newLeaveQuery.setEndDate(new Date(Long.parseLong(end)));
    newLeaveQuery.setTotalHours(Integer.parseInt(hours));
    leaveQueryRepository.save(newLeaveQuery);
}

However when I send a post request to this endpoint I get the following

"{"timestamp":1511444885321,"status":400,"error":"Bad Request","exception":"org.springframework.web.bind.UnsatisfiedServletRequestParameterException","message":"Parameter conditions \"start, end, hours, username\" not met for actual request parameters: ","path":"/api/createleave"}"

When I remove the params argument from the @PostMapping annotation I get a more general error, it will say that it cannot find the first required parameter (start), while it really is being send together with the parameters end, hours and username.

how to get param in method post spring mvc?

I've read in this post that @RequestParam can only be used for get methods, but if I remove @RequestParam and stick with the params argument of the @PostMapping annotation it still doesn't work. I know I can use @RequestBody but I do not want to make a class just for those 4 parameters. Can anyone tell me how I can make this work?

Thank you

EDIT: I'm reading here https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/bind/annotation/RequestMapping.html#params-- that the argument params isn't exactly what I thought it was. It seems to be used as a condition. If a set of parameters match a value then the endpoint controller method will be activated.

回答1:

What you are asking for is fundamentally wrong. POST requests sends data in a body payload, which is mapped via @RequestBody. @RequestParam is used to map data through the URL parameters such as /url?start=foo. What you are trying to do is use @RequestParam to do the job of @RequestBody.

Alternative solutions for REST controllers

Introduce a DTO class. It is the most preferred and clean method.
If you really want to avoid creating a class, you can use @RequestBody Map<String, String> payload. Be sure to include 'Content-Type': 'application/json' in your request header.
If you really want to use @RequestParam, use a GET request instead and send your data via URL parameters.

Alternative solutions for MVC controllers

Introduce a DTO class and use it with annotation @ModelAttribute.
If you transform the form data into JSON, you can use @RequestBody Map<String, String> payload. To do this, please see this answer.

It is not possible to map form data encoded data directly to a Map<String, String>.

回答2:

Well, I think the answer by @Synch is fundamentally wrong, and not the question being asked.

First of all, I use @RequestParam in a lot of scenarios expecting either GET or POST HTTP messages and I'd like to say, that it works perfectly fine;
POST Message's data payload (body), which is referred to the most voted answer (again, by @Synch) is actually the text data, which can perfectly legally be paramname=paramvalue key-value mapping(s) alike (see POST Message Body types here);
docs.spring.io, an official source for Spring Documentation, clearly states, that:

In Spring MVC, "request parameters" map to query parameters, form data, and parts in multipart requests.

So, I think the answer is YES, you can use @RequestParam annotation with @Controller class's method's parameter, as long as that method is request-mapped by @RequestMapping and you don't expect Object, this is perfectly legal and there's nothing wrong with it.

回答3:

You should use @RequestBody instead of using @RequestParam And you should provide whole object as a body of request @RequestParam is for GET, and not POST method

you can do something like public saveUser(@RequestBody User user) { do something with user }

and it will be mapped as User object for example

回答4:

@PostMapping("/createleave")
public void createLeave(@RequestParam Map<String, String> requestParams){

    String start = requestParams.get("start");
    String end= requestParams.get("end");
    String hours= requestParams.get("hours");
    String username = requestParams.get("username");

    System.out.println("Entering createLeave " + start + " " + end + " " + hours + " " + username);
}

This is for multipart/form-data enctype post request.

来源：https://stackoverflow.com/questions/47457382/can-i-use-requestparam-annotation-for-a-post-request

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