Java Controller not transforming for JSON to entity

Question

I have been unable to receive information from a JSON send through a POST request, that looks something like this:

[{
 "idVehicule": 1,
 "vacancies": 3
}]

I have a simple controller that tries to get that JSON sent from front, convert it into a testModel:

import com.fasterxml.jackson.annotation.JsonProperty;

public class testModel {

    @JsonProperty( "idvehicle" )
    private int idvehicle;
    @JsonProperty( "vacancies" )
    private String vacancies;

    public int getIdvehicle() {
        return idvehicle;
    }
    public void setIdvehicle(int idvehicle) {
        this.idvehicle = idvehicle;
    }
    public String getVacancies() {
        return vacancies;
    }
    public void setVacancies(String vacancies) {
        this.vacancies = vacancies;
    }

}

And then it just prints one of its values.

@RequestMapping(value = "/vehicle", method = RequestMethod.POST)
    public ResponseEntity<String> vehicleTest(@RequestBody testModel testModel){
        System.out.println(testModel.getVacancies());
        return new ResponseEntity<String>(HttpStatus.OK);;
    }

After trying the method with postman, i keep getting this error:

{
  "timestamp": 1472819769941,
  "status": 400,
  "error": "Bad Request",
  "exception": "org.springframework.http.converter.HttpMessageNotReadableException",
  "message": "Could not read document: Can not deserialize instance of testModel out of START_ARRAY token\n at [Source: java.io.PushbackInputStream@646345e6; line: 1, column: 1]; nested exception is com.fasterxml.jackson.databind.JsonMappingException: Can not deserialize instance of testModel out of START_ARRAY token\n at [Source: java.io.PushbackInputStream@646345e6; line: 1, column: 1]",
  "path": "/vehicle"
}

I have also tried changing the JSON and then the problem is that the method is unable to convert it into the enity, making the variable "testModel" always null

{"testModel":{"idvehicle":1,"vacancies":3}}

Removing the "@RequestBoby" annotation gives the same problem that the paragraph before.

Any ideas that could help me figure out the problem? Thanks

Send it as plain JSON... {"idvehicle":1,"vacancies":3}. Also idvehicle will not match setIdVehicle it should be idVehicle in that case. — M. Deinum
– M. Deinum, Commented Sep 2, 2016 at 13:04
Please place this as an answer so i can accept it, since this is the correct one. Thanks — user2690047
– user2690047, Commented Sep 5, 2016 at 7:00

Arpit Aggarwal · Accepted Answer · 2016-09-05 07:18:08Z

1

You are specifying @JsonProperty as idvehicle in your testModel so correct the JSON you are posting to:

 [{
     "idvehicle": 1,
     "vacancies": 3
 }]

Next, you are sending the array of testModel and expecting testModel which will of-course will not deserialize.

Either correct the JSON you are sending to {"idvehicle": 1,"vacancies": 3} or change the Controller to accept array of testModel as follows:

@RequestMapping(value = "/vehicle", method = RequestMethod.POST)
public ResponseEntity<String> vehicleTest(@RequestBody List<testModel> testModel){

        return new ResponseEntity<String>(HttpStatus.OK);;
}

answered Sep 5, 2016 at 7:18

Arpit Aggarwal

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1 Comment

user2690047 Over a year ago

Thanks, well explained, i decided to change the JSON structure as advice for you and @M. Deinum , also the problem was that the JSON fields must be identical to the class attributes.

Srini · Accepted Answer · 2016-09-02 13:17:54Z

1

JsonProperty is case sensitive. You need to have the key name exactly same as that in Json. So change it like this and check the spelling also.

@JsonProperty( "idVehicule" )

answered Sep 2, 2016 at 13:17

Srini

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Comments

rorschach · Accepted Answer · 2016-09-05 07:01:06Z

0

You're POSTing an array of of testModel objects (quick gripe, classnames should start with uppercase letters, so it should be TestModel) but your method accepts one testModel as @RequestBody. Change the method declaration to public ResponseEntity<String> vehicleTest(@RequestBody List<testModel> testModel){

answered Sep 5, 2016 at 7:01

rorschach

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