Spring Boot @RequestBody 将空值绑定到默认值？

Question

我有一个 Spring Boot 服务，它使用自定义 POJO 类作为 POST 请求正文。 当客户端将其中一个字段作为空值传递时，我希望将该值设置为 0。

@Data
public class CardAnswer {
    private Integer answerId = 0; //should always be 0 and never set to null
    private String value;
}

由以下控制器使用：

@RequestMapping(value = "/{category}", method = RequestMethod.POST)
    public SalesPulseMResponse updateSecurity(@PathVariable(value = SalesedgeConstants.CATEGORY)
                                              @RequestBody CardAnswer requestBody) {

        return fooService.updateFieldsByCategory(category, requestBody);
    }

Spring Boot 将为我处理从 JSON 到CardAnswer的数据绑定，但是每当answerId被传递为 null 时，我希望它保留 0。重视自己？ 目前，如果客户端未在其请求 JSON 中传入此字段，它将保留默认值，但是，即使对于传入的空值，我也希望保留该默认值。

Answer 1

int有这个属性，所以：

@Data
public class CardAnswer {
    private int answerId;
    private String value;
}

例子：

@Data
public class CounterRequest {
    private final int int1;
    private final int int2;
}

@Data
public class CounterResult {
    private final int value;
}

@RestController
@RequestMapping(
        produces = MediaType.APPLICATION_JSON_UTF8_VALUE,
        consumes = MediaType.APPLICATION_JSON_VALUE)
public class CounterRestController {
    public static final String ADD_URL = "/counter/add";
    
    @RequestMapping(value = ADD_URL,
            method = RequestMethod.POST)
    public CounterResult add(@RequestBody @Valid
            CounterRequest counterRequest) {
        return new CounterResult(counterRequest.getInt1() + counterRequest.getInt2());
    }
}

跑：

$ curl -X POST -H "Content-Type: application/json"  --data "{\"int1\":null,\"int2\":2}" localhost:8080/counter/add
{"value":2}
$ curl -X POST -H "Content-Type: application/json"  --data "{\"int1\":1,\"int2\":2}" localhost:8080/counter/add
{"value":3}

Answer 2

您可以使用@JsonIgnore

@Data
public class CardAnswer {
    @JsonIgnore
    private Integer answerId = 0;
    private String value;
}