nautechsystems/nautilus_trader · error

Gamma {scope} filter '{key}' must contain non-empty comma-se

Error message

Gamma {scope} filter '{key}' must contain non-empty comma-separated values

What it means

List-valued Gamma filters must be non-empty, comma-separated strings with no blank entries. parse_gamma_filter_list splits on ',' and trims each item; empty results or any empty item trigger this error.

Source

Thrown at crates/adapters/polymarket/src/providers.rs:1004

    value.parse::<u64>().map_err(|e| {
        anyhow::anyhow!("Gamma {scope} filter '{key}' must be an unsigned integer: {e}")
    })
}

fn parse_gamma_filter_decimal(scope: &str, key: &str, value: &str) -> anyhow::Result<Decimal> {
    parse_decimal_exact(value)
        .map_err(|e| anyhow::anyhow!("Gamma {scope} filter '{key}' must be a decimal number: {e}"))
}

fn parse_gamma_filter_list(scope: &str, key: &str, value: &str) -> anyhow::Result<Vec<String>> {
    let values = value
        .split(',')
        .map(str::trim)
        .map(str::to_string)
        .collect::<Vec<_>>();

    if values.is_empty() || values.iter().any(String::is_empty) {
        anyhow::bail!("Gamma {scope} filter '{key}' must contain non-empty comma-separated values")
    }
    Ok(values)
}

fn parse_gamma_numeric_filter_list(
    scope: &str,
    key: &str,
    value: &str,
) -> anyhow::Result<Vec<u64>> {
    parse_gamma_filter_list(scope, key, value)?
        .into_iter()
        .map(|item| {
            item.parse::<u64>().map_err(|e| {
                anyhow::anyhow!(
                    "Gamma {scope} filter '{key}' values must be unsigned integers: {e}"
                )
            })
        })

View on GitHub (pinned to 18893faf8b)

Solutions

1. Remove the key entirely when there is nothing to filter on, instead of passing an empty string
2. Fix the value so all comma-separated entries are non-empty (e.g. '1,2,3')
3. Filter empty items in the caller and skip setting the key if the result is empty

Example fix

// before
let list = tags.join(","); // tags is empty -> ""
filters.insert("tag_id".into(), list);
// after
if !tags.is_empty() {
    filters.insert("tag_id".into(), tags.join(","));
}

fn gamma_list(v: &str) -> Option<String> {
    let items: Vec<&str> = v.split(',').map(str::trim).filter(|s| !s.is_empty()).collect();
    if items.is_empty() { None } else { Some(items.join(",")) }
}

fn is_valid_gamma_list(v: &str) -> bool {
    !v.is_empty() && v.split(',').all(|s| !s.trim().is_empty())
}

When it happens

Trigger: Passing '', ' ', 'a,,b', or ',x' for a list filter key (e.g. tag ids or slugs) in a market filter map.

Common situations: Joining an empty Vec with ','; optional filters left as empty strings from config; trailing commas from user input or CSV round-trips.

Understand the failure class

Background: "must not be empty", "cannot be empty" — required-field validation errors across open-source libraries — this error's family across 41 libraries.

Related errors

• Gamma {scope} filter '{key}' must be true or false, was '{va
• Gamma {scope} filter '{key}' cannot be empty
• Unknown Gamma market filter key '{key}'
• Unknown Gamma event filter key '{key}'
• invalid Derive `expired` filter: {e}

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/15eb37f40dec3f77. Report an issue: GitHub.