@RequestBody如何区分未发送的值和空值?

时间:2016-11-15 13:07:24

标签: java json spring spring-mvc jackson

@PatchMapping("/update")
HttpEntity<String> updateOnlyIfFieldIsPresent(@RequestBody Person person) {
    if(person.name!=null) //here
}

如何区分未发送的值和空值?如何检测客户端是否发送了空或跳过字段?

1 个答案:

答案 0 :(得分:2)

上述解决方案需要对方法签名进行一些更改,以克服请求主体自动转换为POJO(即Person对象)。

方法1: -

不是将请求主体转换为POJO类(Person),而是将对象作为Map接收并检查是否存在键&#34; name&#34;。

@PatchMapping("/update")
public String updateOnlyIfFieldIsPresent1(@RequestBody Map<String, Object> requestBody) {

    if (requestBody.get("name") != null) {
        return "Success" + requestBody.get("name"); 
    } else {
        return "Success" + "name attribute not present in request body";    
    }


}

方法2: -

以字符串形式接收请求正文并检查字符序列(即名称)。

@PatchMapping("/update")
public String updateOnlyIfFieldIsPresent(@RequestBody String requestString) throws JsonParseException, JsonMappingException, IOException {

    if (requestString.contains("\"name\"")) {
        ObjectMapper mapper = new ObjectMapper();
        Person person = mapper.readValue(requestString, Person.class);
        return "Success -" + person.getName();
    } else {
        return "Success - " + "name attribute not present in request body"; 
    }

}