android - Moshi将嵌套的JSON值映射到字段

Question

有没有办法将嵌套的JSON值映射到字段而无需其他类？我有JSON回应

{
    "title": "Warriors",
    "artist": "Imagine Dragons",
    "apple_music": {
        "url": "https://music.apple.com/us/album/warriors/1440831203?app=music&at=1000l33QU&i=1440831624&mt=1",
        "discNumber": 1,
        "genreNames": [
            "Alternative",
            "Music"
        ],
    }
}

但是从apple_music我只需要url值。因此，我决定创建Kotlin数据类，并尝试了带有@Json批注的选项

data class Song(
    val title: String,
    val artist: String,
    @Json(name = "apple_music.url")
    val appleMusicUrl: String
)

但是，这不起作用。
它在运行时引发异常

Required value 'appleMusicUrl' (JSON name 'apple_music.url') missing at $

下面的代码正在工作

data class Song(
    val title: String,
    val artist: String,
    @Json(name = "apple_music")
    val appleMusic: AppleMusic
)

data class AppleMusic(val url: String)

我有几个嵌套的值，并且为它们创建额外的类非常麻烦。除了为apple_music节点创建嵌套类之外，还有什么更好的方法吗？

Answer 1

一种方法是使用alternate type adapters using @JsonQualifier。例如:

@Retention(RUNTIME)
@JsonQualifier
annotation class AppleMusicUrl

data class Song(
    val title: String,
    val artist: String,
    @AppleMusicUrl
    val appleMusicUrl: String
)

@FromJson
@AppleMusicUrl
fun fromJson(json: Map<String, Any?>): String {
    return json.getValue("url") as String
}