nautechsystems/nautilus_trader · error

invalid type for 'order_iv': {value}, expected string or num

Error message

invalid type for 'order_iv': {value}, expected string or number

What it means

'order_iv' (implied volatility for Bybit options orders) must be convertible to a price string. The parser tries get_price_str which accepts strings or numbers; any other JSON value type causes this bail, embedding the offending value in the message.

Source

Thrown at crates/adapters/bybit/src/common/parse.rs:1893

    if result.sl_order_type == Some(BybitOrderType::Limit) && result.sl_limit_price.is_none() {
        anyhow::bail!("'sl_order_type' is 'Limit' but 'sl_limit_price' was not provided");
    }

    if result.tp_limit_price.is_some() && result.tp_order_type != Some(BybitOrderType::Limit) {
        anyhow::bail!("'tp_limit_price' requires 'tp_order_type' to be 'Limit'");
    }

    if result.sl_limit_price.is_some() && result.sl_order_type != Some(BybitOrderType::Limit) {
        anyhow::bail!("'sl_limit_price' requires 'sl_order_type' to be 'Limit'");
    }

    result.close_on_trigger = params.get_bool("close_on_trigger");

    if let Some(value) = params.get("order_iv") {
        match get_price_str(params, "order_iv") {
            Some(s) => result.order_iv = Some(s),
            None => {
                anyhow::bail!("invalid type for 'order_iv': {value}, expected string or number")
            }
        }
    }

    if let Some(value) = params.get("mmp") {
        match value.as_bool() {
            Some(b) => result.mmp = Some(b),
            None => anyhow::bail!("invalid type for 'mmp': {value}, expected bool"),
        }
    }

    if let Some(value) = params.get("smp_type") {
        let smp_type = value.as_str().ok_or_else(|| {
            anyhow::anyhow!("invalid type for 'smp_type': {value}, expected string")
        })?;
        result.smp_type = Some(parse_smp_type(smp_type)?);
    }

View on GitHub (pinned to 18893faf8b)

Solutions

  1. Pass 'order_iv' as a string (e.g. "0.42") or a JSON number
  2. Sanitize the source value before inserting it into params

Example fix

// before
params.set("order_iv", true);
// after
params.set("order_iv", "0.42");
Defensive patterns

Strategy: type-guard

Validate before calling

fn validate_order_iv(params: &Params) -> Result<(), String> {
    if let Some(v) = params.get("order_iv") {
        if !matches!(v, Value::String(_) | Value::Number(_)) {
            return Err(format!("order_iv must be string or number, got {v}"));
        }
    }
    Ok(())
}

Type guard

fn is_iv_like(v: &Value) -> bool {
    matches!(v, Value::String(_) | Value::Number(_))
}

Try / catch

match parse_bybit_tp_sl_params(&params) {
    Ok(p) => submit(p),
    Err(e) if e.to_string().contains("invalid type for 'order_iv'") => {
        log::warn("order_iv must be a string or number");
    }
    Err(e) => return Err(e),
}

Prevention

When it happens

Trigger: Passing 'order_iv' as a bool, null, array, or object in the params map.

Common situations: Programmatically built params where order_iv came from a loosely typed config or an untyped JSON blob (e.g. 0.42 parsed as bool-like or nested value).

Understand the failure class

Background: Type mismatch errors: IllegalArgumentException, TypeError and type guards across 150 open-source libraries — this error's family across 150 libraries.

Related errors

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/20d41809ec5168d6. Report an issue: GitHub.