序列化数据类结合内置修改

Question

I am working on updating the parsing of an API response that uses a Serialized Data Class to parse the JSON response. The serialization works perfectly fine right now, but the new data that I'm attempting to parse into data class is not fully reliant on data in the json. Here is what I mean by that:

The data class is Career , and the new data I need to parse is a set of skills and each have a rating . The json data is very simple and contains the skills as such:

{
    // other career data

    ... 

    "mathematics_skill": 8,
    "critical_thinking_skill": 6

    ... // the remaining skills
}

Using straight serialization, I would only be able to store the data as such:

data class Career(
    // Other career data
    @serializableName("mathematic_skill") val mathSkill: Int,
    @serializableName("critical_thinking_skill") val mathSkill: Int,
    // remaining skills
)

However, I would like to store all skills in an array variable of a custom skills class that not only contains the rating, but also the name of the skill and a color. Basically, when I access the skills data of a career, I would like to access it like such:

val careerMathSkill = career.skills[0]
val mathRating = careerMathSkill.rating
val mathColor = careerMathSkill.color

Is it possible to use the serialized data from the data class to add non-serialized data to the same data class? (Sorry for the weird wording, not sure how else to explain it)

EDIT: Here is what I have:

class CareersRemote(
    @SerializedName("careers") val careers: List<Career>
) {

    companion object {
        fun parseResponse(response: Response<CareersRemote>): CareersResponse {
        return if (response.isSuccessful) {
            response.body()!!.format()
        } else
           CareersResponse(listOf(CareersResponse.ErrorType.Generic()))
        }
    }

    fun format(): CareersResponse {

        val careers = topCareers.map {
            Career(
                id = it.id,
                title = it.title,
            )
        }.toMutableList()

        return CareersResponse(CareersResponse.SuccessData(careers = careers))
    }

    data class Career(
        @SerializedName("id") val id: String,
        @SerializedName("title") val title: String,
    )
}

Here is what I am hoping to do in a way

class CareersRemote(
    @SerializedName("careers") val careers: List<Career>
) {

    companion object {
        fun parseResponse(response: Response<CareersRemote>): CareersResponse {
        return if (response.isSuccessful) {
            response.body()!!.format()
        } else
           CareersResponse(listOf(CareersResponse.ErrorType.Generic()))
        }
    }

    fun format(): CareersResponse {

        val careers = topCareers.map {
            Career(
                id = it.id,
                title = it.title,
            )
        }.toMutableList()

        return CareersResponse(CareersResponse.SuccessData(careers = careers))
    }

    data class Career(
        @SerializedName("id") val id: String,
        @SerializedName("title") val title: String,

        // skills array that will need to be filled out based on the data I got in the json
        var skills: List<Skill>

    )
}

EDIT: The suggested solution

class CareersRemote(
    @SerializedName("careers") val careers: List<Career>
) {

    companion object {
        fun parseResponse(response: Response<CareersRemote>): CareersResponse {
        return if (response.isSuccessful) {
            response.body()!!.format()
        } else
           CareersResponse(listOf(CareersResponse.ErrorType.Generic()))
        }
    }

    fun format(): CareersResponse {

        val careers = topCareers.map {
            Career(
                id = it.id,
                title = it.title,
            )
        }.toMutableList()

        return CareersResponse(CareersResponse.SuccessData(careers = careers))
    }

    data class Career(
        @SerializedName("id") val id: String,
        @SerializedName("title") val title: String,
        @SerializedName("math_skill") val mathSkill: Int
        @SerializedName("other_skill") val mathSkill: Int
    ) {

         var skills: List<Skill> = {
              val mathSkill = Skill(name: "Math", rating: mathSkill, color: /**some color*/)
              val otherSkill = Skill(name: "Other", rating: otherSkill, color: /**some color*/)
              return listOf(mathSkill, otherSkill)
         }

    }

}

Answer 1

Yes, you can create a custom JsonDeserializer to modify how the JSON is parsed.

Here is a basic example of what that would look like.

class CareerDeserializer : JsonDeserializer<Career> {

    override fun deserialize(json: JsonElement, typeOfT: Type, context: JsonDeserializationContext): Career {
        val obj = json.asJsonObject

        // standard career data
        val id = obj.get("id")?.asString
        val name = obj.get("name").asString

        // making a Skill object
        val skill = Skill(
                obj.get("mathematic_skill").asInt,
                obj.get("critical_thinking_skill").asInt,
                obj.get("swimming_skill").asInt
                // etc
        )

        return Career(id, name, skill)
    }
}

And make sure to register that within your GsonBuilder.

val gson = GsonBuilder()
                    .registerTypeAdapter(Career::class.java, CareerDeserializer())
                    .create()

Note, you'll also have to create a JsonSerializer if you want to go the other way too.

Edit:

However, if you're just looking to change the syntax of how you're accessing that data, you can do something like this.

data class Career(
        // Other career data
        val mathSkill: Int,
        val thinkSkill: Int
        // remaining skills
) {

    val skills: List<Int>
        get() = listOf(mathSkill, thinkSkill)

}

This would give you a skills list back whenever you needed it, and it would be created when you accessed it, so you won't have to worry about the data being out of sync. This would allow you to access your data as such.

career.skills[0] // get the math skill.

And you can take this another step further by adding a get operator to your Career class.

data class Career(
        // Other career data
        val mathSkill: Int,
        val thinkSkill: Int
        // remaining skills
) {
    ...

    operator fun get(pos: Int) = skills[pos]

}

Now, you can simply do

career[0] // get the math skill.

Warning, this is dangerous because you're accessing an Array so you could get OutOfBoundsExceptions . Use constants to help you out.

Edit 2:

val skills = {
    listOf(Skill("Math", mathSkill, /** some color */ ),
            Skill("Other", otherSkill, /** some color */ ))
}