[英]Java return only attributes of superclass
I am trying to create an API controller with java and spring boot. 我正在尝试使用java和spring boot创建一个API控制器。 I want to return specific objects as JSON from specific API endpoints, nothing special so far. 我想从特定的API端点返回特定对象作为JSON,到目前为止没什么特别的。 Now I have a child class A and a parent class B. B is abstract and A is not abstract, but A contains more attributes than B. I have to pass the attributes of the superclass from A to the API endpoint, but when I cast the an object to an object of the superclass the JSON code contains always the attributes from A. 现在我有一个子类A和一个父类B.B是抽象的,A不是抽象的,但A包含的属性多于B.我必须将超类的属性从A传递给API端点,但是当我强制转换时作为超类对象的对象,JSON代码始终包含来自A的属性。
Is there another way to prevent this than setting the not relevant parts to null or empty elements? 是否有另一种方法可以防止这种情况,而不是将不相关的部分设置为null或空元素?
EDIT: 编辑:
I have the following Code: 我有以下代码:
@Entity
public abstract class B {
private String name;
private String description;
/* GETTERS AND SETTERS */
}
@Entity
public class A extends B {
private String moreInformation;
/* GETTERS AND SETTERS */
}
@RestController
@RequestMapping("/api/v1/")
public class ApiController {
@RequestMapping(value = "/Bs", method = RequestMethod.GET)
public ResponseEntity<List<B>> getBs() {
List<A> As = DAO.getAllRelevantAsAsList();
List<B> Bs = new ArrayList<>();
Bs.appendAll(As);
return new ResponseEntity<>(Bs, HttpStatus.OK);
}
/* DIFFERENT API ENDPOINTS */
}
The JSON Code generated by the API Endpoint looks like this: API端点生成的JSON代码如下所示:
[
{
"name": "CONTENT",
"description": "CONTENT",
"moreInformation": "CONTENT"
},
...
]
I found a possible solution for this problem by annotating the attributes of class A with @JsonIgnore. 我通过使用@JsonIgnore注释类A的属性找到了解决此问题的可能方法。 But the main question of this thread is not limited to this special implementation: Is it possible to get only the attributes of the parent class A without annotating the subclass? 但是这个线程的主要问题不仅限于这个特殊的实现:是否有可能只获取父类A的属性而不注释子类?
I believe your options are: 我相信你的选择是:
@JsonIgnore
on the fields you don't want serialized in A. @JsonIgnore
关于你不想在A中序列化的字段 @JsonProperty
. 将Jackson ObjectMapper配置为仅序列化带注释的字段 ,然后使用@JsonProperty
注释要在B中序列化的字段。 Copy the A instances returned from getAllRelevantAsAsList()
into a new object type which doesn't have the fields (either an anonymous implementation of B which delegates to a, or create a new child class that extends B but doesn't have new fields and has a copy ctor for an A instance. 将从getAllRelevantAsAsList()
返回的A实例复制到一个没有字段的新对象类型中(B的匿名实现委托给a,或者创建一个扩展B但没有新字段的新子类,有一个A实例的副本。
List<B> Bs = DAO.getAllRelevantAsAsList() .stream() .map(a -> new B() { public String getName() { a.getName(); } public void setName(String name) { a.setName(name); } /** other delegated getters and setters **/ }).collect(Collectors.toList());
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