JSON to TypeScript and Kotlin
Paste a sample JSON value and read TypeScript interfaces and Kotlin data classes. Nested objects, arrays and missing keys follow the sample.
- From a sample
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How to use it
- Paste a JSON object, array or value.
- Name the root type, and choose interface or type.
- Copy or download the TypeScript and the Kotlin.
What the sample decides
An object becomes an interface and a Kotlin data class. A nested object gets its own name from the key, and an array of objects uses the singular of that key. A key that is present on one object in an array and absent on another becomes optional. Null stays null in TypeScript and a nullable type in Kotlin. An empty array is unknown in TypeScript and Any in Kotlin, and a note says so.
Numbers that fit in a Kotlin Int are Int, larger whole numbers that fit in a Long are Long, and a number written in a way JavaScript keeps exactly stays a number or a Double. A whole number past that range is a string in TypeScript and a String in Kotlin, and the digits are kept. camelCase Kotlin names keep the original key on @SerialName when the spelling differs, and a Kotlin keyword is wrapped so it stays a legal name. A key that appears twice uses the later value. The types describe the sample. A date that is a string in the JSON stays a string.
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Questions
Does this write Kotlin as well as TypeScript?
Yes. The left box is TypeScript, as an interface or a type alias. The right box is Kotlin data classes, with kotlinx.serialization imports when the sample needs them.
What makes a field optional?
In an array of objects, a key that is missing from one of the objects becomes optional. A null value is included in the type.
How are big numbers written?
A whole number that fits in a Kotlin Int or Long uses that type. A number JavaScript cannot store exactly is a string in TypeScript and a String in Kotlin, and a note names the key.
What about a key like user_id or class?
With camelCase on, user_id becomes userId and keeps @SerialName("user_id"). The word class is a Kotlin keyword, so the property is written in backticks and keeps the original key.
From the same developer
- Catalog - UI: the matching app.
