# XO0413: unknown derive argument

`derive Json` and `derive SqlRow` take one argument, `case:`, which is snake, camel, pascal, or kebab: it converts the keys of the fields without their own wire name. Other derives take no arguments. See core 2.2.

## Example

```xo
struct User {
  user_id: Int
} derive Json(case: shouty)
```

## Fix

```xo
struct User {
  user_id: Int
} derive Json(case: camel)
```

Run `xo explain XO0413` for this text in a terminal, or see
[section 10.6 of the specification](../../spec/core/#106-diagnostic-codes).