It could be very simple but it will be very helpful for me to understand...
I used #ResponseBody in my restcontroller to return String value to browser. The response string is successfully received in browser.
ie:
#RequestMapping(value="/foo", method=RequestMethod.GET)
#ResponseBody
public String foo() {
return "bar";
}
What is the content-type of above response? If this is going to be like writing setAttribute in servlet response what could the attribute name?
If the browser accept only "application/json" how spring will treat the response?
Submitted code produces text/html, as do all mapped Controller methods by default. If you want to produce application/json, you have to change your RequestMapping to
#RequestMapping(value="/foo", method=RequestMethod.GET, produces = "application/json")
However this is not a valid Json String, you would have to change it because the method you submitted would return empty body. The submitted example would be valid text/plain.
When the request contains header "Accept: application/json" and other content type is returned, Spring returns Json-type response explaining that HttpMediaTypeNotAcceptableException was thrown.
Regarding the servlet analogy - please explain, I don't fully understand what you mean. The String is returned as response body, it's very different from request attributes. What would you like to achieve?
I assume the content type will be plain/text. If the request sets accept to "application/json" it depends on your browser/tool. Most rest clients won't display it as it is not application/json. If you invoke the API directly I would assume it is displayed due to browser content sniffing (can be disabled via a header).
Related
I'm working on some Pact Contract tests, using RestPactRunner, in the provider side, and I have the following problem. The endpoint return an "application/json" Content-type header when body is present like
ResponseEntity<>(anyValidBody, HttpStatus.OK)
But when no body is present, like this response
ResponseEntity<>(HttpStatus.FORBIDDEN)
an "Content-Type:text/plain" header is sent to the Client by default, even when produces = APPLICATION_JSON_VALUE is present in the method signature (and Contract Test fails because It's expecting an application/json header)
I was looking for a way to set the default content-type header in test level, but didn't found anything useful.
Any ideas? thanks in advance
The response type for an HttpResponse is usually specified in the request mapping
eg:-
#RequestMapping(value = "/url", method = RequestMethod.GET,
produces = "application/json; charset=utf-8")
If its not specified spring would provide defaults in this case spring would provide application/json if any data is present and text/plain when there is not data.There is a method with following signature in which you can provide the headers for the response, you can set the content type using this method
public ResponseEntity(T body, MultiValueMap<String, String> headers, HttpStatus status)
I am trying to do a get call with request body(JSON) as the request parameter list exceeds the limit. I am able to send the request via postman/insomnia and request is reaching till controller without any error. But the "requstBody" is empty at controller. What i am missing here?
#GET
#Path("\path")
#Consumes(APPLICATION_JSON)
#Produces(APPLICATION_JSON)
public Response getResponse(String requestBody) throws IOException { }
When I replaced #GET with #POST, requestBody has value. For GET call do we need to add anything more?
I am trying to do a get call with request body(JSON) as the request parameter list exceeds the limit. I am able to send the request via postman/insomnia and request is reaching till controller without any error. But the "requstBody" is empty at controller. What i am missing here?
One thing you are missing is the fact that the semantics of a request body with GET are not well defined.
RFC 7231, Section 4.3.1:
A payload within a GET request message has no defined semantics; sending a payload body on a GET request might cause some existing implementations to reject the request.
There are two ways for sending parameters in an Http Get method. PathVariable and RequestParam. In this way, sent parameters are visible in the request URL. for example:
www.sampleAddress.com/countries/{parameter1}/get-time?city=someValues
In the above request, parameter1 is a path variable and parameter2 is a request parameter. So an example of a valid URL would be:
www.sampleAddress.com/countries/Germany/get-time?city=berlin
To access these parameters in a java controller, you need to define a specific name for the parameters. For example the following controller will receive this type of requests:
#GetMapping(value = "/countries/{parameter1}/get-time", produces = "application/json; charset=utf-8")
public String getTimeOfCities(
#PathVariable(value = "parameter1") String country,
#RequestParam(value = "city") String city
){
return "the method is not implemented yet";
}
You are able to send RequestBody through a Get request but it is not recommended according to this link.
yes, you can send a body with GET, and no, it is never useful
to do so.
This elaboration in elasticsearch website is nice too:
The HTTP libraries of certain languages (notably JavaScript) don’t allow GET requests to have a request body. In fact, some users are suprised that GET requests are ever allowed to have a body.
The truth is that RFC 7231—the RFC that deals with HTTP semantics and
content—does not define what should happen to a GET request with a
body! As a result, some HTTP servers allow it, and some—especially
caching proxies—don’t.
If you want to use Post method, you are able to have RequestBody too. In the case you want to send data by a post request, an appropriate controller would be like this:
#PostMapping(value = "/countries/{parameter1}/get-time", produces = "application/json; charset=utf-8")
public String getTimeOfCitiesByPost(
#PathVariable(value = "parameter1") String country,
#RequestParam(value = "city") String city,
#RequestBody Object myCustomObject
){
return "the method is not implemented yet";
}
myCustomObject could have any type of data you defined in your code. Note that in this way, you should send request body as a Json string.
put #RequestBody on String requestBody parameter
#RequestMapping("/path/{requestBody}")
public Response getResponse(#PathVariable String requestBody) throws IOException { }
I have an web application and I'm trying to creat a simple POSt method that will have a value inside the body request:
#RequestMapping(value = "/cachettl", method = RequestMethod.POST)
#CrossOrigin(origins = "http://localhost:3000")
public #ResponseBody String updateTtl(#RequestBody long ttl) {
/////Code
}
My request which I call from some rest client is:
POST
http://localhost:8080/cachettl
Body:
{
"ttl": 5
}
In the response I get 403 error "THE TYPE OF THE RESPONSE BODY IS UNKNOWN
The server did not provide the mandatory "Content-type" header."
Why is that happening? I mention that other GET requests are working perfectly.
Thanks!
Edit:
When I tried it with postman the error message I got is "Invalid CORS request".
Spring application just doesn't know how to parse your message's body.
You should provide "header" for your POST request to tell Spring how to parse it.
"Content-type: application/json" in your case.
You can read more about http methods here: https://developer.mozilla.org/en-US/docs/Learn/HTML/Forms/Sending_and_retrieving_form_data
Updated:
Just in case of debug, remove useless annotations to test only POST mechanism. Also, change types of arg and return type. And try to use case-sensitive header.
#RequestMapping(value = "/cachettl", method = RequestMethod.POST)
public void updateTtl(#RequestBody String ttl) {
System.out.println("i'm working");
}
Since the error is about the response type, you should consider adding a produces attribute, i.e :
#RequestMapping(value = "/cachettl", method = RequestMethod.POST, produces=MediaType.APPLICATION_JSON_VALUE)
Since you are also consuming JSON, adding a consumes attribute won't hurt either :
#RequestMapping(value = "/cachettl", method = RequestMethod.POST, consumes=MediaType.APPLICATION_JSON_VALUE, produces=MediaType.APPLICATION_JSON_VALUE)
The error message is slightly misleading. Your server code is not being hit due an authentication error.
Since you say spring-security is not in play then I suspect you're being bounced by a CORS violation maybe due to a request method restriction. The response body generated by this failure (if any at all) is automatic and will not be of the application/json type hence the client failure. I suspect if you hit the endpoint with something that doesn't care for CORS such as curl then it will work.
Does your browser REST client allow you to introspect the CORS preflight requests to see what it's asking for?
I'm working on a Spring MVC application and have a client that I have no control over. This client is POSTing JSON data but transmitting a application/x-www-form-urlencoded header. Spring naturally trusts this header and tries to receive the data but can't because its JSON. Has anyone had experience overriding the header that Spring receives or just specifying exactly what type of data is coming, regardless of the headers?
You can do two things;
Change the client to send the Content-Type:
application/json header
Write a Servlet Filter or Spring Interceptor which is on top of the Spring Controller and checks for the header Content-Type. If it is not application/json then it changes it to application/json.
Why don't you write a separate controller to handle application/x-www-form-urlencoded requests. If the request is a valid JSON, then you can parse it and forward it to to appropriate service.
This way you can also handle a case in future where you get request of same type which is not a valid JSON.
#RequestMapping(value = "/handleURLEncoded", method = RequestMethod.POST, consumes = MediaType.APPLICATION_FORM_URLENCODED_VALUE)
public #ResponseBody Object handleURLEncoded(HttpEntity<String> httpEntity) {
String json = httpEntity.getBody();
//now you have your request as a String
//you can manipulate it in any way
if(isJSONValid(json)) {
JSONObject jsonObj = new JSONObject(json);
//forward request or call service directly from here
//...
}
//other cases where it's not a valid JSON
}
Note: isJSONValid() method copied from this answer
For example if we have -
#RequestMapping(value = "/someurl", method = {
RequestMethod.POST, RequestMethod.GET}, produces = {
MediaType.TEXT_HTML_VALUE, MediaType.APPLICATION_JSON_VALUE})
#ResponseBody
Edit
What will be the response content-type?
For two different accept headers -
text/html, application/xhtml+xml, * /*
*/ *
Thanks
It depends on configured content negotiation and type selected by request. For example if request has header Accept: application/json or client requested resource with suffix ".json" he will receive json response. http://spring.io/blog/2013/05/11/content-negotiation-using-spring-mvc
Your understanding of the parameter is wrong. It does filter the incoming request by types the client accepts. As an example: If you are just producing "text/html" but the client only accepts "application/json" your mapped function in the controller denies the request.
Side note: Which type to produce can be configured with content negotiation