Spring MVC: Complex object as GET @RequestParam

Java Problem Overview

Suppose i have a page that lists the objects on a table and i need to put a form to filter the table. The filter is sent as an Ajax GET to an URL like that: http://foo.com/system/controller/action?page=1&prop1=x&prop2=y&prop3=z

And instead of having lots of parameters on my Controller like:

@RequestMapping(value = "/action")
public @ResponseBody List<MyObject> myAction(
    @RequestParam(value = "page", required = false) int page,
    @RequestParam(value = "prop1", required = false) String prop1,
    @RequestParam(value = "prop2", required = false) String prop2,
    @RequestParam(value = "prop3", required = false) String prop3) { ... }

And supposing i have MyObject as:

public class MyObject {
    private String prop1;
    private String prop2;
    private String prop3;

    //Getters and setters
    ...
}

I wanna do something like:

@RequestMapping(value = "/action")
public @ResponseBody List<MyObject> myAction(
    @RequestParam(value = "page", required = false) int page,
    @RequestParam(value = "myObject", required = false) MyObject myObject,) { ... }

Is it possible? How can i do that?

Java Solutions

Solution 1 - Java

You can absolutely do that, just remove the @RequestParam annotation, Spring will cleanly bind your request parameters to your class instance:

public @ResponseBody List<MyObject> myAction(
    @RequestParam(value = "page", required = false) int page,
    MyObject myObject)

Solution 2 - Java

I will add some short example from me.

The DTO class:

public class SearchDTO {
    private Long id[];

    public Long[] getId() {
	    return id;
    }

    public void setId(Long[] id) {
	    this.id = id;
    }
    // reflection toString from apache commons
    @Override
    public String toString() {
	    return ReflectionToStringBuilder.toString(this, ToStringStyle.SHORT_PREFIX_STYLE);
    }
}

Request mapping inside controller class:

@RequestMapping(value="/handle", method=RequestMethod.GET)
@ResponseBody
public String handleRequest(SearchDTO search) {
	LOG.info("criteria: {}", search);
	return "OK";
}

Query:

http://localhost:8080/app/handle?id=353,234

Result:

[http-apr-8080-exec-7] INFO  c.g.g.r.f.w.ExampleController.handleRequest:59 - criteria: SearchDTO[id={353,234}]

I hope it helps :)

UPDATE / KOTLIN

Because currently I'm working a lot of with Kotlin if someone wants to define similar DTO the class in Kotlin should have the following form:

class SearchDTO {
    var id: Array<Long>? = arrayOf()

    override fun toString(): String {
        // to string implementation
    }
}

With the data class like this one:

data class SearchDTO(var id: Array<Long> = arrayOf())

the Spring (tested in Boot) returns the following error for request mentioned in answer:

> "Failed to convert value of type 'java.lang.String[]' to required type > 'java.lang.Long[]'; nested exception is > java.lang.NumberFormatException: For input string: "353,234""

The data class will work only for the following request params form:

http://localhost:8080/handle?id=353&id=234

Be aware of this!

Solution 3 - Java

Since the question on how to set fields mandatory pops up under each post, I wrote a small example on how to set fields as required:

public class ExampleDTO {
	@NotNull
	private String mandatoryParam;

	private String optionalParam;
	
	@DateTimeFormat(iso = ISO.DATE) //accept Dates only in YYYY-MM-DD
	@NotNull
	private LocalDate testDate;

	public String getMandatoryParam() {
		return mandatoryParam;
	}
	public void setMandatoryParam(String mandatoryParam) {
		this.mandatoryParam = mandatoryParam;
	}
	public String getOptionalParam() {
		return optionalParam;
	}
	public void setOptionalParam(String optionalParam) {
		this.optionalParam = optionalParam;
	}
	public LocalDate getTestDate() {
		return testDate;
	}
	public void setTestDate(LocalDate testDate) {
		this.testDate = testDate;
	}
}

//Add this to your rest controller class
@RequestMapping(value = "/test", method = RequestMethod.GET)
public String testComplexObject (@Valid ExampleDTO e){
	System.out.println(e.getMandatoryParam() + " " + e.getTestDate());
	return "Does this work?";
}

Solution 4 - Java

I have a very similar problem. Actually the problem is deeper as I thought. I am using jquery $.post which uses Content-Type:application/x-www-form-urlencoded; charset=UTF-8 as default. Unfortunately I based my system on that and when I needed a complex object as a @RequestParam I couldn't just make it happen.

In my case I am trying to send user preferences with something like;

 $.post("/updatePreferences",  
    {id: 'pr', preferences: p}, 
    function (response) {
 ...

On client side the actual raw data sent to the server is;

...
id=pr&preferences%5BuserId%5D=1005012365&preferences%5Baudio%5D=false&preferences%5Btooltip%5D=true&preferences%5Blanguage%5D=en
...

parsed as;

id:pr
preferences[userId]:1005012365
preferences[audio]:false
preferences[tooltip]:true
preferences[language]:en

and the server side is;

@RequestMapping(value = "/updatePreferences")
public
@ResponseBody
Object updatePreferences(@RequestParam("id") String id, @RequestParam("preferences") UserPreferences preferences) {

    ...
        return someService.call(preferences);
    ...
}

I tried @ModelAttribute, added setter/getters, constructors with all possibilities to UserPreferences but no chance as it recognized the sent data as 5 parameters but in fact the mapped method has only 2 parameters. I also tried Biju's solution however what happens is that, spring creates an UserPreferences object with default constructor and doesn't fill in the data.

I solved the problem by sending JSon string of the preferences from the client side and handle it as if it is a String on the server side;

client:

 $.post("/updatePreferences",  
    {id: 'pr', preferences: JSON.stringify(p)}, 
    function (response) {
 ...

server:

@RequestMapping(value = "/updatePreferences")
public
@ResponseBody
Object updatePreferences(@RequestParam("id") String id, @RequestParam("preferences") String preferencesJSon) {


        String ret = null;
        ObjectMapper mapper = new ObjectMapper();
        try {
            UserPreferences userPreferences = mapper.readValue(preferencesJSon, UserPreferences.class);
            return someService.call(userPreferences);
        } catch (IOException e) {
            e.printStackTrace();
        }
}

to brief, I did the conversion manually inside the REST method. In my opinion the reason why spring doesn't recognize the sent data is the content-type.

Solution 5 - Java

While answers that refer to @ModelAttribute, @RequestParam, @PathParam and the likes are valid, there is a small gotcha I ran into. The resulting method parameter is a proxy that Spring wraps around your DTO. So, if you attempt to use it in a context that requires your own custom type, you may get some unexpected results.

The following will not work:

@GetMapping(produces = APPLICATION_JSON_VALUE)
public ResponseEntity<CustomDto> request(@ModelAttribute CustomDto dto) {
    return ResponseEntity.ok(dto);
}

In my case, attempting to use it in Jackson binding resulted in a com.fasterxml.jackson.databind.exc.InvalidDefinitionException.

You will need to create a new object from the dto.

Solution 6 - Java

Yes, You can do it in a simple way. See below code of lines.

URL - http://localhost:8080/get/request/multiple/param/by/map?name='abc'; & id='123'

 @GetMapping(path = "/get/request/header/by/map")
	public ResponseEntity<String> getRequestParamInMap(@RequestParam Map<String,String> map){
		// Do your business here 
		return new ResponseEntity<String>(map.toString(),HttpStatus.OK);
	}

Solution 7 - Java

Accepted answer works like a charm but if the object has a list of objects it won't work as expected so here is my solution after some digging.

Following this thread advice, here is how I've done.

Frontend: stringify your object than encode it in base64 for submission.
Backend: decode base64 string then convert the string json into desired object.

It isn't the best for debugging your API with postman but it is working as expected for me.

> Original object: { page: 1, size: 5, filters: [{ field: "id", value: 1, comparison: "EQ" } > > Encoded object: eyJwYWdlIjoxLCJzaXplIjo1LCJmaWx0ZXJzIjpbeyJmaWVsZCI6ImlkUGFyZW50IiwiY29tcGFyaXNvbiI6Ik5VTEwifV19

@GetMapping
fun list(@RequestParam search: String?): ResponseEntity<ListDTO> {
    val filter: SearchFilterDTO = decodeSearchFieldDTO(search)
    ...
}

private fun decodeSearchFieldDTO(search: String?): SearchFilterDTO {
    if (search.isNullOrEmpty()) return SearchFilterDTO()
    return Gson().fromJson(String(Base64.getDecoder().decode(search)), SearchFilterDTO::class.java)
}

And here the SearchFilterDTO and FilterDTO

class SearchFilterDTO(
    var currentPage: Int = 1,
    var pageSize: Int = 10,
    var sort: Sort? = null,
    var column: String? = null,
    var filters: List<FilterDTO> = ArrayList<FilterDTO>(),
    var paged: Boolean = true
)

class FilterDTO(
    var field: String,
    var value: Any,
    var comparison: Comparison
)

Content Type	Original Author	Original Content on Stackoverflow
Question	renanleandrof	View Question on Stackoverflow
Solution 1 - Java	Biju Kunjummen	View Answer on Stackoverflow
Solution 2 - Java	Przemek Nowak	View Answer on Stackoverflow
Solution 3 - Java	FluffyDestroyerOfCode	View Answer on Stackoverflow
Solution 4 - Java	hevi	View Answer on Stackoverflow
Solution 5 - Java	DKO	View Answer on Stackoverflow
Solution 6 - Java	vkstream	View Answer on Stackoverflow
Solution 7 - Java	Gabriel Brito	View Answer on Stackoverflow