JSON to Kotlin data class generator

How to use it

1. Paste a JSON sample, ideally with several items in each array so optional keys are found.
2. Choose plain data classes or kotlinx.serialization annotations.
3. Copy the code into a .kt file and rename Root and the other classes to fit your domain.

How it works

The sample is read into a shape: every key with every type seen there, and all objects of an array merged into one class.

• Class names come from keys: items holds a List, line_items a List. Root is first.
• Properties are val, one per line, with a trailing comma (Kotlin 1.4+).
• With kotlinx.serialization, imports cover Serializable, SerialName and JsonElement only when used.
• A top-level array gives a typealias, such as typealias Root = List.

Worked example

{"line_items":[{"sku":"A","note":null,"qty":1},{"sku":"B","note":"x"}]} with kotlinx.serialization gives:

import kotlinx.serialization.SerialName
import kotlinx.serialization.Serializable

@Serializable
data class Root(
    @SerialName("line_items")
    val lineItems: List<LineItem>,
)

@Serializable
data class LineItem(
    val sku: String,
    val note: String?,
    val qty: Long? = null,
)

Tips

• Decode with Json.decodeFromString<Root>(text); add Json { ignoreUnknownKeys = true } if the real data has more keys than the sample.
• Change Long to Int where values are known to be small.
• For Android projects using Gson, pick Plain and replace the comments with @SerializedName.