HumanSignal/label-studio · error · ValidationError

random(min, max) requires two arguments.

Error message

random(min, max) requires two arguments.

What it means

The DataManager 'random' expression fills a column with random integers in [min, max]. add_expression enforces exactly two arguments and raises this ValidationError when len(args) != 2 (zero, one, or three-plus arguments).

Source

Thrown at label_studio/data_manager/actions/data_columns.py:299

    args = [] if len(args) == 1 and args[0] == '' else args
    for i, arg in enumerate(args):
        args[i] = arg.replace(';', ',').replace("'", '"')

    sample_values = None

    if command == 'range':
        if len(args) != 1:
            raise ValidationError({'value': 'range(start:int) requires one start argument.'})
        start = int(args[0])

    elif command == 'sample':
        if args:
            raise ValidationError({'value': 'sample() does not accept arguments.'})
        sample_values = iter(random.sample(range(0, size), size))

    elif command == 'random':
        if len(args) != 2:
            raise ValidationError({'value': 'random(min, max) requires two arguments.'})
        minimum, maximum = int(args[0]), int(args[1])

    elif command == 'choices':
        if not 0 < len(args) < 3:
            raise ValidationError({'value': 'choices(values:list, weights:list) requires one or two arguments.'})
        weights = json.loads(args[1]) if len(args) == 2 else None
        choices = json.loads(args[0])

    elif command == 'replace':
        if len(args) != 2:
            raise ValidationError({'value': 'replace(old_value, new_value) requires two arguments.'})
        old_value, new_value = json.loads(args[0]), json.loads(args[1])

    else:
        raise ValidationError('Undefined expression, you can use: ' + add_data_field_examples)

    offset = 0
    task_iterator = iterate_queryset(queryset.only('id', 'data'), chunk_size=settings.UPDATE_COLUMN_BATCH_SIZE)

View on GitHub (pinned to 0b49e9b539)

Solutions

1. Supply exactly two arguments: {"command": "random", "args": ["1", "100"]} for min and max
2. Ensure both values are integers (they are passed through int(args[i]))
3. If no bounds are desired, use sample() with no args or range(start) instead

Example fix

// before
{"command": "random", "args": ["10"]}
// after
{"command": "random", "args": ["0", "10"]}

if (expr.command === 'random' && (!Array.isArray(expr.args) || expr.args.length !== 2)) {
  throw new Error('random requires exactly [min, max]');
}

function isValidRandom(e) { return e.command === 'random' && Array.isArray(e.args) && e.args.length === 2 && e.args.every(a => Number.isFinite(Number(a))); }

try {
  await dm.addAction({id: 'add_data_field', expression: expr});
} catch (e) {
  if (String(e).includes('random(min, max) requires two')) {
    expr.args = [String(min), String(max)];
    return retry();
  }
  throw e;
}

When it happens

Trigger: Calling the add-data-field action with {"command": "random", "args": []}, {"command": "random", "args": ["10"]}, or {"command": "random", "args": ["1","10","5"]} via the column mutation action.

Common situations: Developers assume random() needs no bounds (like Python's random.random), or supply min only expecting max defaults; UI form that sends empty strings for unset bounds.

Related errors

• sample() does not accept arguments.
• choices(values:list, weights:list) requires one or two argum
• replace(old_value, new_value) requires two arguments.
• Undefined expression, you can use: {add_data_field_examples}
• Can't find '{action_id}' in registered actions

AI-assisted analysis of HumanSignal/label-studio@0b49e9b539 (2026-08-29). Data as JSON: /api/errors/c6342ae754edeb96. Report an issue: GitHub.