nautechsystems/nautilus_trader · error · anyhow::Error

Invalid ticker format '{ticker}', base and quote cannot be e

Error message

Invalid ticker format '{ticker}', base and quote cannot be empty

What it means

Validation in validate_ticker_format: the ticker split on '-' yields two parts but at least one is empty, meaning it is malformed like '-USD' or 'BTC-'. A valid dYdX ticker is BASE-QUOTE with both sides non-empty.

Source

Thrown at crates/adapters/dydx/src/http/parse.rs:158

    Ok(Bar::new(
        bar_type, open, high, low, close, volume, ts_event, ts_init,
    ))
}

/// Validates that a ticker has the correct format (BASE-QUOTE).
///
/// # Errors
///
/// Returns an error if the ticker is not in the format "BASE-QUOTE".
pub fn validate_ticker_format(ticker: &str) -> anyhow::Result<()> {
    let parts: Vec<&str> = ticker.split('-').collect();
    if parts.len() != 2 {
        anyhow::bail!("Invalid ticker format '{ticker}', expected 'BASE-QUOTE' (e.g., 'BTC-USD')");
    }

    if parts[0].is_empty() || parts[1].is_empty() {
        anyhow::bail!("Invalid ticker format '{ticker}', base and quote cannot be empty");
    }
    Ok(())
}

/// Parses base and quote currency codes from a ticker.
///
/// # Errors
///
/// Returns an error if the ticker format is invalid.
pub fn parse_ticker_currencies(ticker: &str) -> anyhow::Result<(&str, &str)> {
    validate_ticker_format(ticker)?;
    let parts: Vec<&str> = ticker.split('-').collect();
    Ok((parts[0], parts[1]))
}

/// Returns true if the market status is Active.
#[must_use]
pub const fn is_market_active(status: &DydxMarketStatus) -> bool {

View on GitHub (pinned to 18893faf8b)

Solutions

  1. Ensure both base and quote currency segments are non-empty before joining with `-`
  2. Trim and validate currency strings before formatting the ticker

Example fix

// before
let ticker = format!("{base}-USD"); // base was empty
// after
if base.is_empty() { anyhow::bail!("base currency is empty"); }
let ticker = format!("{base}-USD");
Defensive patterns

Strategy: validation

Validate before calling

fn is_valid_ticker(t: &str) -> bool {
    let parts: Vec<&str> = t.split('-').collect();
    parts.len() == 2 && !parts[0].is_empty() && !parts[1].is_empty()
}

Prevention

When it happens

Trigger: Passing tickers like `"-USD"`, `"BTC-"`, or `"-"` to `parse_ticker_currencies`/`validate_ticker_format`.

Common situations: Mangled string slicing when composing tickers programmatically (e.g. dropping the base currency variable); template or env variables that expand to empty values.

Understand the failure class

Background: "invalid id" errors: invalid identifier format — why libraries reject IDs before lookup, and how to fix them — this error's family across 37 libraries.

Related errors

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/3e9b1befbb0ac79b. Report an issue: GitHub.