how handle null in nested JSON object? - json

Question

I have Dto with field private Category category2;
#Entity
#Getter
#Setter
#ToString
#RequiredArgsConstructor
#Builder
#AllArgsConstructor
public class Procurement implements Serializable {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id", nullable = false, unique = true)
private Long id;
#Column(name = "name",columnDefinition = "varchar(1000)")
private String name;
#Column(name = "category",columnDefinition = "varchar(1000)")
private String category;
#Column(name = "type",columnDefinition = "varchar(1000)")
private String type;
#Enumerated(EnumType.ORDINAL)
#Column(name = "status")
private ProcStatus status;
#OneToOne
private Category category2;
CategoryDto:
#Data
#Builder
#NoArgsConstructor
#AllArgsConstructor
#JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class,
property = "id", scope = Long.class)
public class CategoryDto {
private Long id;
private String name;
}
I have controller and method of create new Procurement:
#PutMapping
ResponseEntity<Procurement> createNewProcurement(#RequestBody ProcurementDto procurementDto) {
return ResponseEntity.ok(procurementService.createNewProcurement(procurementDto));
}
I provide json to controller via fetch in js
function createnewprocuremet() {
fetch(`${url}`, {
method: 'PUT', headers: {'Content-Type': 'application/json'},
body: JSON.stringify({
name: name.value,
category2: {id:$('#categoryprocselector').val()}
})
}).then((res) => {
return res.json();
})
.then((data) => {
$table.bootstrapTable('refresh')
tab.show()
name.value = ''
})
.catch(error => console.log(error))
}
category2 not required and user cannot choose it in selector
If not select category id:$('#categoryprocselector').val() = null and send null to controller and i have error org.springframework.http.converter.HttpMessageNotReadableException: JSON parse error
If category selected it`s work ok.
How i can handle this exception?