Type Alias DecoderObject<T>

DecoderObject: {
    [P in keyof Required<T>]:
        | Decoder<T[P]>
        | { decoder: Decoder<T[P]>; fromKey: string }
}

Represents an object that maps properties of a TypeScript type T to decoders used to validate raw JSON values. Each property may either be a Decoder<T[P]> (decoding a field from the same key in the input JSON) or an object with fromKey and decoder to decode from a different input key.

The fromKey option is useful when your TypeScript property name differs from the incoming JSON key (for example, snake_case JSON keys mapped to camelCase TypeScript properties). Errors reported still reference the TypeScript property name (the key of DecoderObject).

Type Parameters

  • T

Example

// Example where the JSON has `first_name`, but our TypeScript property is `firstName`
interface User { firstName: string; lastName: string; age: number }

const decoders: DecoderObject<User> = {
  firstName: { fromKey: 'first_name', decoder: JsonDecoder.string() },
  lastName: { fromKey: 'last_name', decoder: JsonDecoder.string() },
  age: JsonDecoder.number()
};

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