JSON to Kotlin Data Class
Generate kotlinx.serialization data classes from a JSON object
About JSON to Kotlin Data Class
Builds @Serializable data classes for kotlinx.serialization, with camelCase properties and @SerialName where the Kotlin name differs from the key. Whole numbers become Long, decimals Double, nulls and keys missing from some array items nullable with a null default, and mixed or empty values use JsonElement. Types come from one sample, so review them before adding the models to an Android or Ktor project; everything runs client-side.
Category: Converters.
Frequently asked questions
Which dependencies does the generated Kotlin code need?
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The kotlinx-serialization-json library plus the Kotlin serialization compiler plugin (org.jetbrains.kotlin.plugin.serialization in Gradle). Without the plugin the classes still compile, but Json can't find a serializer for them at runtime.
Why are whole numbers typed as Long instead of Int?
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IDs and millisecond timestamps often exceed the Int limit of 2,147,483,647, and Long holds any whole number up to 2^63, so decoding won't overflow. Switch to Int where values are small, and to Double where a field written as 1.0 in the sample can also hold fractions.
How do I decode JSON into the generated classes?
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Call Json.decodeFromString<Root>(text), or Json.decodeFromString<RootList>(text) when the JSON is a top-level array. The default Json rejects keys that aren't in the class, so use Json { ignoreUnknownKeys = true } if the API may add fields.
How are keys like my-key, class or 2fa handled?
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They become valid property names and keep the original key in @SerialName, so my-key turns into myKey and 2fa into _2fa. Kotlin keywords such as class or in are wrapped in backticks, and names that collide after conversion get a numeric suffix.