REST API request using Hibernate relationships

Rest Controller:

@PostMapping("transaction")
public ResponseEntity<Transaction> init(@RequestBody Transaction transactionInput) {
Transaction transaction = transactionRepository.save(transactionInput);
return new ResponseEntity<>(transaction, HttpStatus.OK);
}


Transaction Entity:

@Getter
@Setter
@Entity
@NoArgsConstructor
@AllArgsConstructor
@DynamicInsert
@DynamicUpdate
@Table(name = "transaction")
public class Transaction {

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private long id;

@OneToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL, optional = false)
@JoinColumn(name="currency_id")
private Currency currency;


Currency Entity:

@Entity
@NoArgsConstructor
@AllArgsConstructor
@Getter
@Setter
@DynamicInsert
@DynamicUpdate
@Table(name = "currency")
public class Currency {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private long id;

@Length(max = 3)
private String sign;

@Length(max = 30)
private String name;


Request:

curl -X POST
http://localhost:4000/transaction-service/transaction
-H 'content-type: application/json'
-d '{
"currency_id": 1
}'


And it obviously currency is null and I got this error:

could not execute statement; SQL [n/a]; constraint [currency_id];
nested exception is
org.hibernate.exception.ConstraintViolationException: could not
execute statement

Is there a way to automatically mapping when I sending request with

"currency" = {"name" = "USD"}


Or how should I send this request?

1 Answer
1

You cannot insert Transaction before Currency is inserted. The way you do it, it seems you are trying to insert a Transaction with its optional=false column currency_id set to null.

Transaction

Currency

optional=false

currency_id

null

If you store the Currency entity first, then it should work. I am not sure if there is any good way to make such a "cascade insert" thing.

Currency

Also, this is not a good @OneToOne entity design - there is no constraint that ensures it is really one to one. CurrencyId should either be a primary key or have some unique constraint to ensure it is one to one. There is no apparent meaning of Transaction class from the snippet you posted, either.

@OneToOne

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