JSON to Go Structs, Rust Serde & Python Models

Names are converted, and the original key is preserved in an attribute. A JSON key created_at becomes the exported Go field CreatedAt with the tag json:"created_at", the Rust field created_at under #[serde(rename = "created_at")] when needed, and the Python field created_at directly. This matters because Go only serialises exported (capitalised) fields, so a struct without tags silently produces CreatedAt in its output and fails to match the API.

Each language expresses "maybe absent" differently, and getting it wrong is the usual source of runtime panics. Go has no optional type, so a nullable field needs a pointer (*string) to distinguish absent from empty — otherwise a missing string silently becomes "". Rust makes it explicit with Option<T>, and Serde will error on a missing field that is not optional. Pydantic uses str | None = None. The generator marks what it can see; anything the API can omit but your sample includes has to be widened by hand.

JSON has one numeric type, so inference guesses from the sample: a whole number becomes int64/i64/int and a fractional one becomes float64/f64/float. A field that is integral in your example but occasionally fractional in production will fail to deserialise, so widen it deliberately. Dates arrive as ISO 8601 strings with no type marker; Go can decode them into time.Time, Rust needs chrono with a Serde feature, and Pydantic will coerce a string into datetime automatically.