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How to simplify REST controllers with same methods and different headers?

I have one Java REST API which is used by 2 different consumers. By default REST principles my API should define the names of request headers. But now I have not common situation. Consumers use different security layer which provides different headers which means same parameter in both ways.
Example method: (not real code)
For 1st consumer:
#PostMapping("/number")
Integer getNumber(#RequestHeader("no") String number, #RequestBody User user) {
/*...*/
}
For 2nd consumer:
#PostMapping("/number")
Integer getNumber(#RequestHeader("number") String number, #RequestBody User user) {
/*...*/
}
I have up to 10 methods in one controller and they should be with same name and logic, but different header. The request path prefix could be different.
Question:
How to simplify REST controller and don't create 2 different controllers with same methods and same logic?
What I tried:
I tried several examples to create one controller with 2 different interfaces with same methods, but different mapping.
Example:
Controller class
#RestController
#RequestMapping(path ="/application")
#Api(tags = {"application"})
public class ApplicationController implements AppMapping1, AppMapping2 {
#Override
public Integer getNumber(String number, User user) {
/*...*/
}
}
First interface
interface AppMapping1 {
#PostMapping("/num")
Integer getNumber(#RequestHeader("num") String number, #RequestBody User user);
}
Second interface
interface AppMapping2 {
#PostMapping("/number")
Integer getNumber(#RequestHeader("number") String number, #RequestBody User user);
}
Result:
Controller maps only with the first interface. So http://.../application/num works fine, but http://.../application/number - gets 404 error code. That means Java Spring-Boot doesn't have such functionality. Need some more ideas.
Project developed with Java 8; spring-boot:2.1.1.RELEASE; gradle

According to this , If we're not sure which headers will be present, or we need more of
them than we want in our method's signature, we can use the
#RequestHeader annotation without a specific name.
You have a few choices for variable type: a Map, a MultiValueMap or an HttpHeaders object.
Sample
#PostMapping("/number")
public Integer getNumber(#RequestHeader Map<String, String> headers) {
if (Optional.ofNullable(headers.get("no")).isPresent()){
//...
}
else if (Optional.ofNullable(headers.get("number")).isPresent())
{
//...
}
}

It is not maintenance friendly to repeat the same block of code twice or more times just to receive the same input with different names (number and no). Instead, it is advisable to read all the headers and traverse through it to fetch input using different names.
Sample Code
#PostMapping("/number")
public Integer getNumber(#RequestHeader Map<String, String> headers) {
String number = headers.containsKey("number") ? headers.get("number") : headers.get("no");
if(Objects.isNull(number)) {
throw new RuntimeException("Number input not received from header!");
}
// relevant processing
}

I found this answer on https://www.logicbig.com/tutorials/spring-framework/spring-web-mvc/spring-mvc-request-header.html
Avoid ambiguity by using #RequestMapping(headers = ....)
We can fix the ambiguity similar to #RequestParam where we used
'params' . In case of #RequestHeader we can define related headers in
#RequestMapping annotation.
#Controller
#RequestMapping("trades")
public class TradesController {
#RequestMapping(headers = "User-Agent")
public String handleAllTradesRequests (#RequestHeader("User-Agent") String userAgent,
Model model) {
model.addAttribute("msg", "all trades requests, User-Agent header : "
+ userAgent);
return "my-page";
}
#RequestMapping(headers = "From")
public String handleRequestByFromHeader (#RequestHeader("From") String from,
Model model) {
model.addAttribute("msg", "trade request by From header : " + from);
return "my-page";
}

You could remove the #RequestHeader annotation and consider doing the following:
#PostMapping("/number")
Integer getNumber(HttpServletRequest request, #RequestBody User user) {
String number = request.getHeader("num");
if(number == null){
number = request.getHeader("number");
}
/*...*/
}
If you want a cleaner approach, consider creating a util class that takes the HttpServletRequest object and returns the desired header value.

The best way is to add the HttpServletRequest as an argument of your single controller and do some logic with the header map provided by the HttpServletRequest object.
If you want to see a full example take a look here. I have implemented I single controller that wraps all my logic accordingly to headers/methods and so on. You can customize the logic as you want with the HttpServletRequest.

Java Spring Controller handling a ridiculous url

Okay so I am using a payment service called Thrive cart, I am doing this for a membership website I'm creating. When the user has paid I want them to be redirected to a URL where I can use that data to update the current users information.
The data that get's sent in the params is insane:
http://localhost:5000/user/welcome?thrivecart%5Baccount_id%5D=3196&thrivecart%5Baccount_name%5D=testacount&thrivecart%5Bcustomer%5D%5Bemail%5D=testname8%40gmail.com&thrivecart%5Bcustomer%5D%5Baddress%5D%5Bcountry%5D=GB&thrivecart%5Bcustomer%5D%5Baddress%5D%5Bzip%5D=pe303wu&thrivecart%5Border%5D%5B0%5D%5Bt%5D=product&thrivecart%5Border%5D%5B0%5D%5Bid%5D=6&thrivecart%5Border%5D%5B0%5D%5Bn%5D=Monthly+membership&thrivecart%5Border%5D%5B0%5D%5Bp%5D=799&thrivecart%5Border%5D%5B0%5D%5Bq%5D=1&thrivecart%5Border%5D%5B0%5D%5Bpo%5D=60120&thrivecart%5Border%5D%5B1%5D%5Bt%5D=product&thrivecart%5Border%5D%5B1%5D%5Bid%5D=6&thrivecart%5Border%5D%5B1%5D%5Bn%5D=Monthly+membership&thrivecart%5Border%5D%5B1%5D%5Bp%5D=799&thrivecart%5Border%5D%5B1%5D%5Bq%5D=1&thrivecart%5Border%5D%5B1%5D%5Bpo%5D=60120&thrivecart%5Border_currency%5D=GBP&thrivecart%5Border_id%5D=1041278&thrivecart%5Border_tax%5D=0.2&thrivecart%5Border_tax_id%5D=gb&thrivecart%5Border_total%5D=799&thrivecart%5Bpayment_processor%5D=paypal&thrivecart%5Bproduct_id%5D=6&thrivecart%5Bpurchases%5D%5B0%5D=6&thrivecart%5Bpurchases%5D%5B1%5D=6&thrivecart_hash=a5b711d2288b4cb587511811bc0a3473
So far I've set up a simple controller which doesn't get hit:
#RestController
#RequestMapping("/user")
public class UserController {
#RequestMapping(value = "/welcome", method = RequestMethod.POST)
public void welcomeMember(#PathVariable String data) {
System.out.println(data);
}
}
How do I deal with crazy data like this? Do I have to specific each path param?

First of all, what you seem to get are not path elements but request parameters, so you will need #RequestParam annotations to get the values.
Since there are so many request parameters, I would also recommend to take just one parameter, a Map<String, String>. That Map will contain all the parameters as key/value pairs, for example:
key: "thrivecart[account_id]"
value: "3196"
If you're not sure whether you receive a POST or a GET request, you can also add a second parameter to receive the HttpMethod.
Change your RestController to:
#RestController
#RequestMapping("/user")
public class UserController {
#RequestMapping(value = "/welcome")
public void welcomeMember(#RequestParam Map<String, String> data, HttpMethod method) {
System.out.println(method);
System.out.println(data);
}
}

That looks like a problem with how the rest api is called from the service consumer side.
try sending the data in a request body rather then as a param. This way you can use a POJO to handle the data.

Question 1: So far I've set up a simple controller which doesn't get hit:
As per your URL http://localhost:5000/user/welcome "user" seems to be your projects context name. Try removing #RequestMapping("/user") from your class.
Also, instead of#PathVariable String data use #RequestParam Map<String,String> params. #PathVariable String data is used when data is part of url but in your case it's parameter. Final code should be like below.
#RestController
public class UserController {
#RequestMapping(value = "/welcome", method = RequestMethod.POST)
public void welcomeMember(#RequestParam Map<String,String> params ) {
for(Map.Entry<String, String> entry : params.entrySet()){
//This will print all paramters name and their value
System.out.println(entry.getKey() + "-" + entry.getValue());
}
}
}
Question 2: How do I deal with crazy data like this? Do I have to specific each path param?
I will suggest to follow standard practice. Send data in json format. There are different ways for this depend upon front end technology you are using. One way is Link

Grab a specific property from JSON payload as MVC method argument

I have asked a similar question before: this one
Now I have a similar but different issue.
My Spring MVC controller model is a JSON payload with a defined set of attributes that, unfortunately, are not part of a class in my project.
E.g.
{
"userId" : "john",
"role" : "admin"
}
I need to treat userId and role as separate Strings.
I currently have two ways to declare the controller method
public ResponseObject mvc(#RequestBody MyCustomDTO dto){
String userId = dto.getUserId();
String role = dto.getRole();
}
public ResponseObject mvc(#RequestBody ModelMap map){
String userId = (String)map.get("userId");
String role = (String)map.get("role");
}
I have been asked to find a different implementation because 1) requires to create a custom DTO class for each combination of parameters (most cases need 1 named parameter, e.g. delete(productId)) and 2) involves an entity that is not strictly defined. Especially when dealing with lists, it can contain arbitrary values that need to be checked at runtime.
Spring MVC, as I have found, does not support resolving #ModelAttribute from a JSON request body. Am I doing something wrong or is it just Spring not doing it? Can I grab a specific property, be it a plain primitive or an entire POJO, from the Request Body into a method argument?
In the second case it would be better to request a useful feature to Spring developers.
Spring version is 4.2.x.
This question is related with the previously linked but differs in the fact that now I will be encapsulating the single property into a Javascript object, so the object that Jackson needs to deserialize won't be a primitive but a POJO.

You won't be able to get individual members as easily, simply because Spring MVC doesn't have any builtin tools to do that. One option is to write your own annotation that describes a parameter at the root of an excepted JSON object body. Then write and register a new HandlerMethodArgumentResolver implementation which processes that annotation on a handler method parameter.
This is not a simple task. Since you can't consume the request content multiple times, you have to save it somehow, in a Filter, for example. For now, let's ignore this restriction and assume we only wanted one parameter. You'd define an annotation
#Retention(RetentionPolicy.RUNTIME)
#Target(ElementType.PARAMETER)
#interface JsonObjectProperty {
String name();
}
And the HandlerMethodArgumentResolver
class JsonObjectPropertyResolver implements HandlerMethodArgumentResolver {
/**
* Configured as appropriate for the JSON you expect.
*/
private final ObjectMapper objectMapper = new ObjectMapper();
#Override
public boolean supportsParameter(MethodParameter parameter) {
return parameter.hasParameterAnnotation(JsonObjectProperty.class);
}
#Override
public Object resolveArgument(MethodParameter parameter, ModelAndViewContainer mavContainer, NativeWebRequest webRequest,
WebDataBinderFactory binderFactory) throws Exception {
Class<?> parameterType = parameter.getParameterType();
HttpServletRequest servletRequest = webRequest.getNativeRequest(HttpServletRequest.class);
ServletServerHttpRequest inputMessage = new ServletServerHttpRequest(servletRequest);
MediaType contentType = inputMessage.getHeaders().getContentType();
if (!contentType.equals(MediaType.APPLICATION_JSON_UTF8)) {
throw new HttpMessageNotReadableException(
"Could not read document. Expected Content-Type " + MediaType.APPLICATION_JSON_UTF8 + ", was " + contentType + ".");
}
// handle potential exceptions from this as well
ObjectNode rootObject = objectMapper.readValue(inputMessage.getBody(), ObjectNode.class);
if (parameterType == String.class) {
JsonObjectProperty annotation = parameter.getParameterAnnotation(JsonObjectProperty.class);
return rootObject.get(annotation.name()).asText();
}
// handle more
throw new HttpMessageNotReadableException("Could not read document. Parameter type " + parameterType + " not parseable.");
}
}
and finally the handler method
#RequestMapping(value = "/json-new", method = RequestMethod.POST, consumes = MediaType.APPLICATION_JSON_VALUE)
#ResponseBody
public String handleJsonProperty(#JsonObjectProperty(name = "userId") String userId) {
String result = userId;
System.out.println(result);
return result;
}
You'll have to register the JsonObjectPropertyResolver appropriately. Once you do, it will be able to extract that JSON property directly into the parameter.

You can use some JSON inline parsers (similar to XML Xpath) where you can provide your JSON string and ask your parser to retrieve some subdocument as String, List or Map. One of the examples is OGNL. It's quite powerful tool, although it is not the only one and not the most performance efficient, but still mature and stable Apache product. So, in your case you would be able feed your JSON string to OGNL and tell it to retrieve properties "userId" and "role" as separate strings. See the OGNL documentation at Apache OGNL page

Spring MVC - How to return simple String as JSON in Rest Controller

My question is essentially a follow-up to this question.
#RestController
public class TestController
{
#RequestMapping("/getString")
public String getString()
{
return "Hello World";
}
}
In the above, Spring would add "Hello World" into the response body. How can I return a String as a JSON response? I understand that I could add quotes, but that feels more like a hack.
Please provide any examples to help explain this concept.
Note: I don't want this written straight to the HTTP Response body, I want to return the String in JSON format (I'm using my Controller
with RestyGWT which requires the response to be in valid JSON
format).

Either return text/plain (as in Return only string message from Spring MVC 3 Controller) OR wrap your String is some object
public class StringResponse {
private String response;
public StringResponse(String s) {
this.response = s;
}
// get/set omitted...
}
Set your response type to MediaType.APPLICATION_JSON_VALUE (= "application/json")
#RequestMapping(value = "/getString", method = RequestMethod.GET,
produces = MediaType.APPLICATION_JSON_VALUE)
and you'll have a JSON that looks like
{ "response" : "your string value" }

JSON is essentially a String in PHP or JAVA context. That means string which is valid JSON can be returned in response. Following should work.
#RequestMapping(value="/user/addUser", method=RequestMethod.POST)
#ResponseBody
public String addUser(#ModelAttribute("user") User user) {
if (user != null) {
logger.info("Inside addIssuer, adding: " + user.toString());
} else {
logger.info("Inside addIssuer...");
}
users.put(user.getUsername(), user);
return "{\"success\":1}";
}
This is okay for simple string response. But for complex JSON response you should use wrapper class as described by Shaun.

In one project we addressed this using JSONObject (maven dependency info). We chose this because we preferred returning a simple String rather than a wrapper object. An internal helper class could easily be used instead if you don't want to add a new dependency.
Example Usage:
#RestController
public class TestController
{
#RequestMapping("/getString")
public String getString()
{
return JSONObject.quote("Hello World");
}
}

You can easily return JSON with String in property response as following
#RestController
public class TestController {
#RequestMapping(value = "/getString", produces = MediaType.APPLICATION_JSON_VALUE)
public Map getString() {
return Collections.singletonMap("response", "Hello World");
}
}

Simply unregister the default StringHttpMessageConverter instance:
#Configuration
public class WebMvcConfiguration extends WebMvcConfigurationSupport {
/**
* Unregister the default {#link StringHttpMessageConverter} as we want Strings
* to be handled by the JSON converter.
*
* #param converters List of already configured converters
* #see WebMvcConfigurationSupport#addDefaultHttpMessageConverters(List)
*/
#Override
protected void extendMessageConverters(List<HttpMessageConverter<?>> converters) {
converters.removeIf(c -> c instanceof StringHttpMessageConverter);
}
}
Tested with both controller action handler methods and controller exception handlers:
#RequestMapping("/foo")
public String produceFoo() {
return "foo";
}
#ExceptionHandler(FooApiException.class)
public String fooException(HttpServletRequest request, Throwable e) {
return e.getMessage();
}
Final notes:
extendMessageConverters is available since Spring 4.1.3, if are running on a previous version you can implement the same technique using configureMessageConverters, it just takes a little bit more work.
This was one approach of many other possible approaches, if your application only ever returns JSON and no other content types, you are better off skipping the default converters and adding a single jackson converter. Another approach is to add the default converters but in different order so that the jackson converter is prior to the string one. This should allow controller action methods to dictate how they want String to be converted depending on the media type of the response.

I know that this question is old but i would like to contribute too:
The main difference between others responses is the hashmap return.
#GetMapping("...")
#ResponseBody
public Map<String, Object> endPointExample(...) {
Map<String, Object> rtn = new LinkedHashMap<>();
rtn.put("pic", image);
rtn.put("potato", "King Potato");
return rtn;
}
This will return:
{"pic":"a17fefab83517fb...beb8ac5a2ae8f0449","potato":"King Potato"}

Make simple:
#GetMapping("/health")
public ResponseEntity<String> healthCheck() {
LOG.info("REST request health check");
return new ResponseEntity<>("{\"status\" : \"UP\"}", HttpStatus.OK);
}

Add produces = "application/json" in #RequestMapping annotation like:
#RequestMapping(value = "api/login", method = RequestMethod.GET, produces = "application/json")
Hint: As a return value, i recommend to use ResponseEntity<List<T>> type. Because the produced data in JSON body need to be an array or an object according to its specifications, rather than a single simple string. It may causes problems sometimes (e.g. Observables in Angular2).
Difference:
returned String as json: "example"
returned List<String> as json: ["example"]

Add #ResponseBody annotation, which will write return data in output stream.

This issue has driven me mad: Spring is such a potent tool and yet, such a simple thing as writing an output String as JSON seems impossible without ugly hacks.
My solution (in Kotlin) that I find the least intrusive and most transparent is to use a controller advice and check whether the request went to a particular set of endpoints (REST API typically since we most often want to return ALL answers from here as JSON and not make specializations in the frontend based on whether the returned data is a plain string ("Don't do JSON deserialization!") or something else ("Do JSON deserialization!")). The positive aspect of this is that the controller remains the same and without hacks.
The supports method makes sure that all requests that were handled by the StringHttpMessageConverter(e.g. the converter that handles the output of all controllers that return plain strings) are processed and in the beforeBodyWrite method, we control in which cases we want to interrupt and convert the output to JSON (and modify headers accordingly).
#ControllerAdvice
class StringToJsonAdvice(val ob: ObjectMapper) : ResponseBodyAdvice<Any?> {
override fun supports(returnType: MethodParameter, converterType: Class<out HttpMessageConverter<*>>): Boolean =
converterType === StringHttpMessageConverter::class.java
override fun beforeBodyWrite(
body: Any?,
returnType: MethodParameter,
selectedContentType: MediaType,
selectedConverterType: Class<out HttpMessageConverter<*>>,
request: ServerHttpRequest,
response: ServerHttpResponse
): Any? {
return if (request.uri.path.contains("api")) {
response.getHeaders().contentType = MediaType.APPLICATION_JSON
ob.writeValueAsString(body)
} else body
}
}
I hope in the future that we will get a simple annotation in which we can override which HttpMessageConverter should be used for the output.

Simple and Straightforward send any object or return simple List
#GetMapping("/response2")
#ResponseStatus(HttpStatus.CONFLICT)
#ResponseBody List<String> Response2() {
List<String> response = new ArrayList<>(Arrays.asList("Response2"));
return response;
}
I have added HttpStatus.CONFLICT as Random response to show how to pass RequestBody also the HttpStatus

Annotate your method with the #ResponseBody annotation to tell spring you are not trying to render a view and simple return the string plain

passing complex input from jquery to Spring MVC

What I would like to achieve is to pass parameters from jquery to a Spring Controller. I was successful in passing simple parameter (one string) from jquery to Spring bu how can I do the same with complex data?
For example: in Spring I expect a POJO as input parameter and this POJO has a String property and a List property.
POJO:
public class SimplePojo {
private String one;
private List<String> two;
...
}
Spring Controller:
#RequestMapping(value = "/something", method = RequestMethod.POST)
public #ResponseBody String check(#RequestParam(????) SimplePojo input) { ... }
JQuery
jq.post("/something", ????, function(data){ ... });
I put question marks to the places where I have no idea what to write :)
Could you please help me?
Thanks, Viktor

In js :
ajax.get('api/checkout_patron/patron_id='+self.patronId())
In java :
#RequestMapping(method= RequestMethod.GET,value = "/patron_id={patron_id}")
public #ResponseBody
Response getPatron(#PathVariable String patron_id){
}
Here js request I have mapped using :
#Controller
#RequestMapping(value = "/api/checkout_patron")
on before class declaration.
Here I am using knockout js, so I am using this pattern to pass request.
Second Small Example with my technique :
var form={
sourceName : self.sourceName(),
sourceEmail :self.email()
}
ajax.post('api/source',JSON.stringify(form)).done(function(response){
});
Here Get data :
#RequestMapping(method= RequestMethod.POST,consumes = "application/json")
public #ResponseBody
ResponseEntity<IWebApiResponse> addBudget(#RequestBody AddBudgetSourceForm form){
//your code to process data
}
AddBudgetSourceForm class :
public class AddBudgetSourceForm {
private String sourceName;
private String sourceEmail;
// getter and setter
}
Keep one thing in mind that name of form class and in js form data-bind should be same (i.e. left side of parameter in js form that have been stringified).
UPDATE :
You can do something like following :
List<String> var = new ArrayList<>();
var.add(form.getSourcename());
var.add(form.getSourceEmail());
and yes you can send data like that in json.
If you are sending single data for each thing then don't use List.
Instead of that use List<classname> and define all required variable in class with getter-setter.