Validation

Validate Niral form actions and RPC inputs with built-in schemas. Coerce form values, validate nested data and return useful field-level error messages.

Built-in coercing schemas — form strings become typed values, errors become field messages. No Zod needed.

export const signup = withSchema(
  {
    email: v.email(),
    age: v.int({ min: 13 }),
    tags: v.array(v.string({ min: 1 }), { min: 1, max: 5 }),
    bio: v.optional(v.string({ max: 500 })),
  },
  async ({ email, age, tags, bio }) => {
    // values are validated AND coerced ("42" → 42, "on" → true)
    return { ok: true }
  }
)

RPC callers get a 400 with { errors: { field: message } } — the thrown

client error carries .errors for form UIs

Ordinary form actions surface it as form.errors.field in props
Reactive form actions expose saving.errors.field on the

formAction("signup") controller without remounting the form

v.file() validates uploads (size, types — image/* wildcards work)

Rules: string, email, int, number, bool, oneOf, array, file, object, optional.

TypeScript infers withSchema handler values and return types, as well as validate(shape, data) results. Check result.ok before using its fully validated value. Nested object errors retain their field structure; array validation errors are a single message for the field.