receiving json and deserializing as List of object at spring mvc controller

Question

My code is as below   controller   RequestMapping value   setTest   method RequestMethod POST  consumes  application json   public  ResponseBody ModelMap setTest  RequestBody List lt TestS gt  refunds  ModelMap map        for TestS r   refunds            System out println r getName                  other codes     TestS pojo  public class TestS implements Serializable       private String name      private String age        getter setter     Json request  var z       name   1   age   2     name   1   age   3        ajax       url    setTest       data  z      type   POST       dataType  json       contentType  application json                       It s giving this error      java lang ClassCastException  java util LinkedHashMap cannot be cast to com air cidb entities TestS   I am using spring 3 1 2 and jackson 2 0 4  Edit  I want to receive list of TestS objects at my controller method  and process them  I am not able to find if I am sending wrong json or my method signature is wrong

User · Answer

Solution works very well    public List lt String gt  savePerson  RequestBody Person   personArray      For this signature you can pass Person array from postman like          empId    10001      tier    Single      someting   6     anything   0     frequency    Quaterly          empId    10001      tier    Single      someting   6     anything   0     frequency    Quaterly        Don t forget to add consumes tag    RequestMapping value     getEmployeeList   method   RequestMethod POST  consumes  application json   produces    application json   public List lt Employee gt  getEmployeeDataList  RequestBody Employee   employeearray

User · Answer

This is not possible the way you are trying it  The Jackson unmarshalling works on the compiled java code after type erasure  So your  public  ResponseBody ModelMap setTest  RequestBody List lt TestS gt  refunds  ModelMap map     is really only  public  ResponseBody ModelMap setTest  RequestBody List refunds  ModelMap map      no generics in the list arg    The default type Jackson creates when unmarshalling a List is a LinkedHashMap   As mentioned by  Saint you can circumvent this by creating your own type for the list like so   class TestSList extends ArrayList lt TestS gt        and then modifying your controller signature to   public  ResponseBody ModelMap setTest  RequestBody TestSList refunds  ModelMap map

User · Answer

Here is the code that works for me  The key is that you need a wrapper class   public class Person        private String name      private Integer age       public String getName             return name             public void setName String name            this name   name             public Integer getAge             return age             public void setAge Integer age            this age   age              Override     public String toString             return  Person  name     name      age     age                A PersonWrapper class  public class PersonWrapper        private List lt Person gt  persons                   return the persons             public List lt Person gt  getPersons             return persons                         param persons the persons to set             public void setPersons List lt Person gt  persons            this persons   persons            My Controller methods   RequestMapping value  person   method RequestMethod POST consumes  application json  produces  application json        ResponseBody     public List lt String gt  savePerson  RequestBody PersonWrapper wrapper            List lt String gt  response   new ArrayList lt String gt             for  Person person  wrapper getPersons             personService save person            response add  Saved person      person toString                   return response          The request sent is json in POST     persons     name   shail1   age   2     name   shail2   age   3       And the response is     Saved person  Person  name shail1  age 2    Saved person  Person  name shail2  age 3

User · Answer

For me below code worked  first sending json string with proper headers    ajax           type   POST           url    save           data   JSON stringify valObject           contentType  application json  charset utf-8           dataType  json           success   function resp               console log resp                      error   function resp               console log resp                       And then on Spring side -   RequestMapping value     save                    method   RequestMethod POST                  consumes  application json   public  ResponseBody String  save  RequestBody ArrayList lt KeyValue gt  keyValList          Saving call goes here     return         Here KeyValue is simple pojo that corresponds to your JSON structure also you can add produces as you wish  I am simply returning string   My json object is like this -     storedKey   vc   storedValue   1   clientId   1   locationId   1       storedKey   vr   storedValue      clientId   1   locationId   1

User · Answer

I believe this will solve the issue  var z       name   1   age   2     name   1   age   3      z   JSON stringify JSON parse z      ajax       url    setTest       data  z      type   POST       dataType  json       contentType  application json

User · Answer

RequestMapping           value  person             method RequestMethod POST           consumes  application json            produces  application json    ResponseBody public List lt String gt  savePerson  RequestBody Person   personArray        List lt String gt  response   new ArrayList lt String gt         for  Person person  personArray            personService save person           response add  Saved person      person toString               return response      We can use Array as shown above

[spring] receiving json and deserializing as List of object at spring mvc controller

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