# Radio

> One value from a small set, rendered as radio buttons.

Source: CBX documentation, version 4.0 preview (unreleased). Canonical page: https://docs.configbox.at/docs/4.0-preview/technical/property-types/radio. Last updated 2026-07-29.

---
One value from a small set, rendered as radio buttons.

**Storage kind:** `column` · **Column:** `varchar(50)`

Use it when the set is short — three or four options — and the operator benefits from seeing all of
them at once without opening anything. Beyond that, [`dropdown`](https://docs.configbox.at/docs/4.0-preview/technical/property-types/dropdown): a radio group of
twelve options is a wall.

## Settings

| Setting | Meaning |
|---|---|
| `choices` | `value => label` map |
| `radios` | Legacy alias for the same thing |
| `default` | Pre-selected value |

`choices` wins; `radios` is only consulted when `choices` is empty. They are alternatives, not
merged.

## How it differs from `dropdown`

Less than you would expect, and in one place more than you would expect.

Storage is identical — the same `varchar(50)`, the same short-token keys. Rendering differs. But
`radio` is **not** a subclass of `dropdown`, and it does not carry `dropdown`'s two extras:

- it does **not** validate membership in `check()`, so an out-of-set value is stored;
- it does **not** filter with exact match, so list filtering uses the base substring `LIKE`.

`getValueSet()` does read `choices`, so a static set still publishes an `enum` to the generated JSON
and MCP schemas — which means a schema-driven caller is constrained even though `check()` would not
have stopped a hand-crafted POST.

If you want the validation, use `dropdown`. If the radio presentation matters and the input is
untrusted, validate in the model's `validateData()`.

`getValueSet()` reads `choices`, then the legacy `radios`, so either spelling publishes an `enum`.
It used to read `choices` only — a definition using `radios` rendered and stored fine while
documenting itself as an unconstrained string. Prefer `choices` in new definitions all the same.

@see dropdown.md