What causes "'value' format requires exactly one key" in nikivdev/code?

Pass exactly one key: `f env pull --format value --keys DATABASE_URL`.

nikivdev/code · error · anyhow::Error

'value' format requires exactly one key

Error message

'value' format requires exactly one key

What it means

Raised by the `value` output format handler, which prints a single raw value (no newline) for piping into other commands. Because raw-value output is only meaningful for exactly one variable, the command enforces that exactly one key was requested and bails otherwise.

Source

Thrown at src/env.rs:3864

    let target = if personal {
        resolve_personal_target()?
    } else {
        resolve_env_target()?
    };
    let vars = fetch_env_vars(&target, environment, keys, !personal)?;

    if vars.is_empty() {
        bail!("No env vars found");
    }

    match format {
        "json" => {
            let json = serde_json::to_string_pretty(&vars)?;
            println!("{}", json);
        }
        "value" => {
            if keys.len() != 1 {
                bail!("'value' format requires exactly one key");
            }
            let key = &keys[0];
            if let Some(value) = vars.get(key) {
                print!("{}", value); // No newline for piping
            } else {
                bail!("Key '{}' not found", key);
            }
        }
        "env" | _ => {
            // Default: KEY=VALUE format
            let mut sorted_keys: Vec<_> = vars.keys().collect();
            sorted_keys.sort();
            for key in sorted_keys {
                let value = &vars[key];
                // Escape for shell
                let escaped = value.replace('\\', "\\\\").replace('"', "\\\"");
                println!("{}=\"{}\"", key, escaped);
            }

View on GitHub (pinned to a747e741ae)

Solutions

Pass exactly one key: `f env pull --format value --keys DATABASE_URL`.
Use `--format env` or `--format json` when you need multiple or all variables.
Shell-evaluate the result when piping: `export $(f env pull --format value --keys KEY)`.

Example fix

// before
f env pull --format value --keys A,B
// after (one key per invocation)
export A=$(f env pull --format value --keys A)
export B=$(f env pull --format value --keys B)

Defensive patterns

Strategy: validation

Validate before calling

# ensure exactly one key is passed before invoking value format
KEYS="a"
count=$(echo "$KEYS" | awk -F, '{print NF}')
[ "$count" -eq 1 ] || { echo "--format value needs exactly one --keys entry" >&2; exit 1; }
f env pull --format value --keys "$KEYS"

Try / catch

// wrapper enforcing the invariant
function env_value() {
  [ "$#" -eq 1 ] || { echo "usage: env_value <single-key>" >&2; return 2; }
  f env pull --format value --keys "$1"
}

Prevention

Use `--format env` or `--format json` when you need more than one variable.
Wrap the value-format call in a shell function that asserts a single argument.
Never call value format without an explicit --keys flag.

When it happens

Trigger: Running e.g. `f env pull --format value` with zero keys (no --keys flag) or with two or more keys in --keys.

Common situations: Forgetting --keys when piping (`f env pull --format value | ...`); listing multiple keys assuming value format prints them all.

Understand the failure class

Background: "Unknown argument", "Invalid value", and "must be one of": invalid CLI argument errors explained — this error's family across 35 libraries.

Related errors

AI-assisted analysis of nikivdev/code@a747e741ae (2026-09-01). Data as JSON: /api/errors/6db72e19f7190526. Report an issue: GitHub.