Question

我有一个实体，有两列引用其他表中的同一列。基本上，交易取决于账户：在创建新交易时，将资金从一个账户汇到另一个账户。

帐户：

@Entity
@Table(name = "accounts")
public class Account implements java.io.Serializable {

    private static final long serialVersionUID = 2612578813518671670L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "idaccount", unique = true, nullable = false)
    private Long idaccount;

    @Column(name = "name", length = 50)
    private String name;

    @NotNull
    @ManyToOne
    @JoinColumn(name = "iduser")
    private User user;

...

交易：

@Entity
@Table(name = "transactions")
public class Transaction {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "idtransaction", unique = true, nullable = false)
    private Long idtransaction;

    private BigDecimal amount;

    @NotNull
    @ManyToOne
    @JoinColumn(name = "SOURCE_ACCOUNT")
    private Account sourceAccount;

    @NotNull
    @ManyToOne
    @JoinColumn(name = "TARGET_ACCOUNT")
    private Account targetAccount;

...

TransactionController

@CrossOrigin
@RestController
@RequestMapping("/transaction")
public class TransactionController {

    @Autowired
    TransactionService transactionService;

    @RequestMapping(method = RequestMethod.POST)
    public ResponseEntity<Transaction> addTransaction(@RequestBody Transaction Transaction) {
        transactionService.save(Transaction);

        return new ResponseEntity<Transaction>(Transaction, HttpStatus.CREATED);
    }

...

如果我尝试发布以创建交易（当然我已经创建了帐户）：

{
"amount": 111,
"sourceAccount": 1,
"targetAccount": 2
}

我明白了：

Failed to read HTTP message: org.springframework.http.converter.HttpMessageNotReadableException: Could not read document: Can not construct instance of com.mycompany.basicbank.model.Account: no int/Int-argument constructor/factory method to deserialize from Number value (1)
 at [Source: java.io.PushbackInputStream@63447acf; line: 3, column: 18] (through reference chain: com.mycompany.basicbank.model.Transaction["sourceAccount"]); nested exception is com.fasterxml.jackson.databind.JsonMappingException: Can not construct instance of com.mycompany.basicbank.model.Account: no int/Int-argument constructor/factory method to deserialize from Number value (1)
 at [Source: java.io.PushbackInputStream@63447acf; line: 3, column: 18] (through reference chain: com.mycompany.basicbank.model.Transaction["sourceAccount"])

所以我的问题是：我应该检查什么才能修复“无法构造com.livingit.basicbank.model.Account的实例：没有int / Int-argument构造函数/工厂方法从数字反序列化”？

Answer 1

问题是您发送的json与class TransactionClient { BigDecimal amount, Long sourceAccount, Long targetAccount }类不完全匹配。因此你会看到错误但是你想要实现的是一个有效的场景，可以做到。

一些选择。

创建一个与json匹配的新类（不是Transaction）。喜欢

{
  "amount": 111,
  "sourceAccount":  {
    "idaccount" :123123,
     ..... // All the Non Null fields
   },
  "targetAccount": {
    "idaccount" :45554,
     ..... // All the Non Null fields
   },
 }

在后端（控制器或某些服务中），您可以使用此sourceAccount和targetAccount从数据库获取Acccounts，并使用此对象创建一个事务对象并保存。

从前端调用后端获取这些源和目标帐户的帐户（json），然后使用json调用您的事务端点
```
{{1}}
```

JsonMappingException：无法构造实例

1 个答案: