HumanSignal/label-studio · error · ValidationError

Select an existing column or enter a new column name.

Error message

Select an existing column or enter a new column name.

What it means

_validate_column_request requires column_name (or value_name/existing_column) to be a non-empty string. If it is missing, empty, whitespace-only, or not a string, ValidationError {'column_name': 'Select an existing column or enter a new column name.'} is raised.

Source

Thrown at label_studio/data_manager/actions/data_columns.py:38

all_permissions = AllPermissions()


def add_or_modify_columns_enabled(project):
    return flag_set('fflag_utc_1012_add_or_modify_columns', organization=project.organization)


def _validate_column_request(request_data, project):
    value_name = (
        request_data.get('column_name') or request_data.get('value_name') or request_data.get('existing_column')
    )
    value_type = request_data.get('value_type', 'String')
    value = request_data.get('value', '')

    if value_type not in {'String', 'Number', 'Expression'}:
        raise ValidationError({'value_type': 'Choose a supported column type.'})

    if not isinstance(value_name, str) or not value_name.strip():
        raise ValidationError({'column_name': 'Select an existing column or enter a new column name.'})

    value_name = value_name.strip()
    column_exists = value_name in project.summary.all_data_columns
    if not column_exists:
        column_exists = project.tasks.filter(data__has_key=value_name).exists()
    mode = 'update' if column_exists else 'add'
    # Existing columns (e.g. imported spreadsheet headers) stay editable, but a new column must be
    # one the Data Manager can filter and sort on.
    if mode == 'add' and not is_queryable_column_name(value_name):
        raise ValidationError(
            {'column_name': f'Column name cannot contain {UNQUERYABLE_COLUMN_NAME_CHARACTERS}.'},
        )
    try:
        value = {'String': str, 'Number': float, 'Expression': str}[value_type](value)
    except (TypeError, ValueError) as exc:
        raise ValidationError({'value': f'Enter a valid {value_type.lower()} value.'}) from exc

    return mode, value_name, value_type, value

View on GitHub (pinned to 0b49e9b539)

Solutions

1. Include a non-empty string column_name (or value_name/existing_column) in the action request data.
2. Trim the value before sending; whitespace-only names are rejected.
3. Fix the payload key so it matches column_name/value_name/existing_column.

Example fix

// before
{'value_type': 'String', 'value': 'x'}
// after
{'value_type': 'String', 'value': 'x', 'column_name': 'my_column'}

name = request_data.get('column_name') or request_data.get('value_name')
assert isinstance(name, str) and name.strip(), 'column_name is required and must be a non-empty string'

def has_valid_column_name(payload):
    name = payload.get('column_name') or payload.get('value_name') or payload.get('existing_column')
    return isinstance(name, str) and bool(name.strip())

from rest_framework.exceptions import ValidationError
try:
    add_data_field(project, qs, request=request)
except ValidationError as e:
    if 'column_name' in e.message_dict:
        prompt_user_for_column_name()

When it happens

Trigger: Submitting add_data_field without column_name/value_name, with column_name: '', or with a non-string (e.g. number) value.

Common situations: Script omits the column name field; UI form field left blank; payload key mismatch (sending 'name' instead of 'column_name').

Understand the failure class

Background: "Missing required field" and "field is required" errors: why libraries reject payloads that omit mandatory fields — this error's family across 20 libraries.

Related errors

• Choose a supported column type.
• Column name cannot contain {UNQUERYABLE_COLUMN_NAME_CHARACTE
• Enter a valid {value_type.lower()} value.
• Expression must use the form command(arguments).
• Expression command is required.

AI-assisted analysis of HumanSignal/label-studio@0b49e9b539 (2026-08-29). Data as JSON: /api/errors/22881fc0d4b37e33. Report an issue: GitHub.