Moshi适配器可跳过List< T>中的不良对象。 [英] Moshi adapter to skip bad objects in the List<T>

问题描述

我使用Moshi，我需要使用越野车解决我的问题。有时，当我请求对象列表时，其中一些不包含必填字段。当然，我可以捕获并处理 JsonDataException ，但是我想跳过这些对象。我该如何使用Moshi？

I use Moshi and I need to solve my problem with a buggy backend. Sometimes, when I request a list of objects, some of them don't contain mandatory fields. Of course, I can catch and process JsonDataException, but I want to skip these objects. How can I do it with Moshi?

更新

我有几个我的任务的模型

I have a couple of models for my task

@JsonClass(generateAdapter = true)
data class User(
        val name: String,
        val age: Int?
)

@JsonClass(generateAdapter = true)
data class UserList(val list: List<User>)

和错误的JSON

{
  "list": [
    {
      "name": "John",
      "age": 20
    },
    {
      "age": 18
    },
    {
      "name": "Jane",
      "age": 21
    }
  ]
}

如您所见，第二个对象没有强制性的 name 字段，我想通过Moshi适配器跳过它。

as you can see, the second object has no mandatory name field and I want to skip it via Moshi adapter.

推荐答案

找到答案了

class SkipBadListObjectsAdapterFactory : JsonAdapter.Factory {
    override fun create(type: Type, annotations: MutableSet<out Annotation>, moshi: Moshi): JsonAdapter<*>? {
        return if (annotations.isEmpty() && Types.getRawType(type) == List::class.java) {
            val elementType = Types.collectionElementType(type, List::class.java)
            val elementAdapter = moshi.adapter<Any>(elementType)

            SkipBadListObjectsAdapter(elementAdapter)
        } else {
            null
        }
    }

    private class SkipBadListObjectsAdapter<T : Any>(private val elementAdapter: JsonAdapter<T>) :
        JsonAdapter<List<T>>() {
        override fun fromJson(reader: JsonReader): List<T>? {
            val goodObjectsList = mutableListOf<T>()

            reader.beginArray()

            while (reader.hasNext()) {
                try {
                    elementAdapter.fromJson(reader)?.let(goodObjectsList::add)
                } catch (e: JsonDataException) {
                    // Skip bad element ;)
                }
            }

            reader.endArray()

            return goodObjectsList

        }

        override fun toJson(writer: JsonWriter, value: List<T>?) {
            throw UnsupportedOperationException("SkipBadListObjectsAdapter is only used to deserialize objects")
        }
    }
}

谢谢其他主题的人 =）

Thank you "guys from the other topics" =)

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