如何排除Jackson json序列化（Scala）中的字段

Question

我想在下面的示例中排除_passthroughFields属性。当我使用调试器时，它看起来像我的PropertyFilter从不使用。我究竟做错了什么？

import java.util 

import com.fasterxml.jackson.databind.ser.impl.SimpleBeanPropertyFilter.SerializeExceptFilter 
import com.fasterxml.jackson.databind.ser.impl.SimpleFilterProvider 
import com.fasterxml.jackson.databind.{DeserializationFeature, ObjectMapper, ObjectWriter} 
import com.fasterxml.jackson.module.scala.DefaultScalaModule 
import com.fasterxml.jackson.module.scala.experimental.ScalaObjectMapper 
import org.scalatest.{Matchers, WordSpec} 

import scala.collection.immutable.Map 

class PassthroughFieldsSpec extends WordSpec with Matchers { 
    "JacksonParser" when { 
    "given an Object and undesired fields" should { 
     "not include those fields in the json response" in { 
     trait Foo { 
      def id: String 
      def _passthroughFields: Map[String, String] = Map.empty 
     } 

     class Bar(val id: String, override val _passthroughFields: Map[String, String]) extends Foo 

     val item = new Bar("abcd", Map.empty) 

     val mapper = new ObjectMapper() with ScalaObjectMapper 
     mapper.registerModule(DefaultScalaModule) 
     mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false) 

     val excludes = new util.HashSet[String](1) 
     excludes.add("_passthroughFields") 
     excludes.add("get_passthroughFields") 

     val filters = new SimpleFilterProvider() 
      .addFilter("filter properties by name", new SerializeExceptFilter(excludes)) 

     val writer: ObjectWriter = mapper.writer(filters) 

     val json = writer.writeValueAsString(item) 
     json.contains("_passthroughFields") shouldBe false 
     } 
    } 
    } 
} 

Answer 1

我想你可以使用@JsonIgnore之类的东西来排除它，或者使字段暂态。

否则，如果您需要在案例类代码之外定义它（例如您的示例），您可以使用Genson来完成。

import com.owlike.genson._ 
import com.owlike.genson.reflect.VisibilityFilter 

// Note that if you use case classes you don't need the visibility filter stuff 
// it is used to indicate that private fields should be ser/de 
val genson = new GensonBuilder() 
    .withBundle(ScalaBundle()) 
    .useFields(true, VisibilityFilter.PRIVATE) 
    .exclude("_passthroughFields") 
    .create() 

genson.toJson(item) 

声明：我是Gensons作者。