Spring MVC Complex object as GET RequestParam

Question

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 amp prop1 x amp prop2 y amp prop3 z  And instead of having lots of parameters on my Controller like    RequestMapping value     action   public  ResponseBody List lt MyObject gt  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 lt MyObject gt  myAction       RequestParam value    page   required   false  int page       RequestParam value    myObject   required   false  MyObject myObject             Is it possible   How can i do that

User · Answer

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 amp preferences 5BuserId 5D 1005012365 amp preferences 5Baudio 5D false amp preferences 5Btooltip 5D true amp 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

User · Answer

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    quot  test quot   method   RequestMethod GET  public String testComplexObject   Valid ExampleDTO e       System out println e getMandatoryParam      quot   quot    e getTestDate         return  quot Does this work  quot

User · Answer

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 lt CustomDto gt  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

User · Answer

You can absolutely do that  just remove the  RequestParam annotation  Spring will cleanly bind your request parameters to your class instance   public  ResponseBody List lt MyObject gt  myAction       RequestParam value    page   required   false  int page      MyObject myObject

User · Answer

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 lt ListDTO gt        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 lt FilterDTO gt    ArrayList lt FilterDTO gt         var paged  Boolean   true    class FilterDTO      var field  String      var value  Any      var comparison  Comparison

User · Answer

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 lt Long gt     arrayOf        override fun toString    String              to string implementation           With the data class like this one   data class SearchDTO var id  Array lt Long gt    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 amp id 234   Be aware of this

User · Answer

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   amp  id  123     GetMapping path     get request header by map       public ResponseEntity lt String gt  getRequestParamInMap  RequestParam Map lt String String gt  map              Do your business here          return new ResponseEntity lt String gt  map toString   HttpStatus OK

[java] Spring MVC: Complex object as GET @RequestParam

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