kotlin data class HttpMessageNotReadableException - json

Question

I'm trying this code with postman, but nothing works, why ?
What i send :
{
"name":"front_msel",
"gitlabId": "83",
"fichierVersion":"VERSION"
}
My spring controller :
#RestController
#RequestMapping("/projects")
class ProjectController(val projectRepository: ProjectRepository) {
private val log = LoggerFactory.getLogger(ProjectController::class.java)
#PostMapping()
fun saveProject(#RequestBody payload: Project): String {
log.info("project: '{}'", payload.toString())
return projectRepository.save(payload).gitlabId?:"-1"
}
}
What i get :
{
"timestamp": 1505917417221,
"status": 400,
"error": "Bad Request",
"exception": "org.springframework.http.converter.HttpMessageNotReadableException",
"message": "JSON parse error: Can not construct instance of com.......model.Project: no suitable constructor found, can not deserialize from Object value (missing default constructor or creator, or perhaps need to add/enable type information?); nested exception is com.fasterxml.jackson.databind.JsonMappingException: Can not construct instance of com.......model.Project: no suitable constructor found, can not deserialize from Object value (missing default constructor or creator, or perhaps need to add/enable type information?)\n at [Source: java.io.PushbackInputStream#66ba61d9; line: 2, column: 2]",
"path": "/projects"
}
My project data class :
data class Project(val name:String?, val gitlabId: String?, val fichierVersion: String?)
I doubled check params, it's not a wording mistake, what does this things doesn't works ?
EDIT :
Thanks to Todd, the problem was resolve by adding null value to my param, to generate a zero argument constructor. Thanks !
data class Project(val name:String? = null, val gitlabId: String? = null, val fichierVersion: String? = null)

Answer 1

I got this to work by making two slight changes.
First, since all your Project fields are nullable, provide default values so the compiler will generate a zero argument constructor:
data class Project(val name:String? = null, val gitlabId: String? = null, val fichierVersion: String? = null)
Second, it seems that Spring wants your fields to be in snakey_case rather than camelCase, so change your payload to this:
{
"name":"front_msel",
"gitlab_id": "83",
"fichier_version":"VERSION"
}