如何从JSON字段名获取Java对象字段的名称

huangapple
go评论106阅读模式
英文:

How to get Java's object field's name from JSON fields name

问题

以下是翻译好的内容：

我想要在响应中过滤掉一些字段。过滤操作应该在将 Java 对象序列化为 JSON 之前执行。
考虑以下情况：

  1. public class Entity {
  3.     @JsonProperty("some_property")
  4.     String someProperty;
  6.     @JsonProperty("nested_entity")
  7.     @OneToMany(mappedBy = "entity", fetch = FetchType.LAZY, cascade = CascadeType.ALL)
  8.     NestedEntity nestedEntity;
  10.     // 其他字段，例如 fieldA，fieldB
  11. }

API 端点：

  1. get api/entity/{id}?fields=some_property,field_a

现在的要求是，在输出中，我们只应该过滤掉 someProperty 和 fieldA 这两个字段。就像这样：

  1. {
  2.     "some_property": "foo",
  3.     "field_a": "bar"
  4. }

但是，由于这些是 JSON 字段，而不是 Java 对象字段，我不能通过反射来进行过滤或获取这些字段。我们是否有办法实现这一点，即根据 JSON 字段来过滤 Java 对象？

附：在序列化之前进行过滤的优点是，除非需要这些字段，否则可以避免 lazy-fields 的数据库调用。

提前感谢您的帮助！

英文:

I want to filter out some fields in the response. Filtering should be done before the Java object is serialised into the JSON.
Consider:

  1. public class Entity {
  3.     @JsonProperty("some_property")
  4.     String someProperty;
  6.     @JsonProperty("nested_entity")
  7.     @OneToMany(mappedBy = "entity", fetch = FetchType.LAZY, cascade = CascadeType.ALL)
  8.     NestedEntity nestedEntity;
  10.     // other fields for eg fieldA, fieldB
  11. }

API endpoint

  1. get api/entity/{id}?fields=some_property,field_a

Now the ask is, in the o/p we should filter out only someProperty and fieldA. Like

  1. {
  2.     "some_property": "foo",
  3.     "field_a": "bar"
  4. }

But since these are JSON fields not Java object fields I can't filter or get these fields them by Reflection. Is there a way we can achieve this, i.e. filtering of Java object based on json fields ?

FYI: The advantage of filtering before serialization is that the lazy-fields' DB calls are saved unless these fields are required

Thanks in advance!

答案1

得分: 1

  1. 关于使用`@JsonFilter`建议来支持空的`fields`或没有字段过滤的建议，以及为了支持这一点，添加了JacksonConfiguration。
  3.     @JsonFilter("entityFilter")
  4.     public class Entity {
  6.         @JsonProperty("some_property")
  7.         String someProperty;
  8.         // 其他字段，例如 fieldA，fieldB
  9.     }
  10. ---
  12.     @Configuration
  13.     public class JacksonConfiguration { 
  14.         public JacksonConfiguration(ObjectMapper objectMapper) {
  15.             objectMapper.setFilterProvider(new SimpleFilterProvider().setFailOnUnknownId(false));
  16.         } 
  17.     }
  18. ---
  20.     public class FieldMapper {
  21.         
  22.         @SneakyThrows
  23.         public static Dto getFilteredFields(Dto make, String fields[]) {
  24.             ObjectMapper objectMapper = new ObjectMapper();
  25.             if(ArrayUtils.isNotEmpty(fields)) {
  26.                 FilterProvider filters = new SimpleFilterProvider().addFilter(
  27.                         "entityFilter", SimpleBeanPropertyFilter.filterOutAllExcept(fields)
  28.                 );
  29.                 objectMapper.setFilterProvider(filters);
  30.             } else {
  31.                 objectMapper.setFilterProvider(new SimpleFilterProvider().setFailOnUnknownId(false));
  32.             }
  33.             JsonNode j = objectMapper.readTree(objectMapper.writeValueAsString(make));
  34.             return objectMapper.convertValue(j, Dto.class);
  35.         }
  36.     }
  38. -----
  40.     // 控制器代码用于获取带有字段dto的api/entity/{id}?fields=some_property,field_a
  41.     Dto filteredFields = getFilteredFields(dto, fields);
  42.     return filteredFields;
英文:

On the suggestion of @robocode using @JsonFilter and also to support empty fields or no fields filtering added JacksonConfiguration

  1. @JsonFilter("entityFilter")
  2. public class Entity {
  4.     @JsonProperty("some_property")
  5.     String someProperty;
  6.     // other fields for eg fieldA, fieldB
  7. }
  1. @Configuration
  2. public class JacksonConfiguration { 
  3.     public JacksonConfiguration(ObjectMapper objectMapper) {
  4.         objectMapper.setFilterProvider(new SimpleFilterProvider().setFailOnUnknownId(false));
  5.     } 
  6. }
  1. public class FieldMapper {
  2.     
  3.     @SneakyThrows
  4.     public static Dto getFilteredFields(Dto make, String fields[]) {
  5.         ObjectMapper objectMapper = new ObjectMapper();
  6.         if(ArrayUtils.isNotEmpty(fields)) {
  7.             FilterProvider filters = new SimpleFilterProvider().addFilter(
  8.                     "entityFilter", SimpleBeanPropertyFilter.filterOutAllExcept(fields)
  9.             );
  10.             objectMapper.setFilterProvider(filters);
  11.         } else {
  12.             objectMapper.setFilterProvider(new SimpleFilterProvider().setFailOnUnknownId(false));
  13.         }
  14.         JsonNode j = objectMapper.readTree(objectMapper.writeValueAsString(make));
  15.         return objectMapper.convertValue(j, Dto.class);
  16.     }
  17. }
  1. // controller code to get the dto for api/entity/{id}?fields=some_property,field_a
  2. Dto filteredFields = getFilteredFields(dto, fields);
  3. return filteredFields

huangapple
  • 本文由 发表于 2020年10月16日 03:23:21
  • 转载请务必保留本文链接：https://go.coder-hub.com/64378410.html
  • hibernate
  • jackson
  • java
  • json
  • spring
匿名

发表评论

匿名网友

:?: :razz: :sad: :evil: :!: :smile: :oops: :grin: :eek: :shock: :???: :cool: :lol: :mad: :twisted: :roll: :wink: :idea: :arrow: :neutral: :cry: :mrgreen:

确定