calcom/cal.diy · error · BadRequestException

Invalid type for booking field '${eventTypeBookingField.name

Error message

Invalid type for booking field '${eventTypeBookingField.name}'. Expected type ${expectedBookingFieldResponseValueType} (compatible with field type '${eventTypeBookingFieldType}'), but received ${bookingFieldResponseValueType}.

What it means

Thrown at the end of the per-field validation switch as a fallback when isValidType is false for any booking field whose type was handled (string, number, boolean, select, multiselect, checkbox, radio, url). The message reports the expected JS type, the field's declared type, and the received type. BadRequestException (HTTP 400).

Source

Thrown at apps/api/v2/src/platform/bookings/2024-08-13/services/bookings.service.ts:365

                  `Invalid option '${submittedValue}' for booking field '${
                    eventTypeBookingField.name
                  }'. Allowed options are: ${allowedOptionValues.join(", ")}.`
                );
              }
            }
            break;
          case "url":
            expectedBookingFieldResponseValueType = "string";
            isValidType = bookingFieldResponseValueType === "string";
            break;
          default:
            // note(Lauris): by default pass the field if we have a missing "case" in the switch
            isValidType = true;
            break;
        }

        if (!isValidType) {
          throw new BadRequestException(
            `Invalid type for booking field '${eventTypeBookingField.name}'. Expected type ${expectedBookingFieldResponseValueType} (compatible with field type '${eventTypeBookingFieldType}'), but received ${bookingFieldResponseValueType}.`
          );
        }
      }
    }

    return true;
  }

  private isValidSingleOptionValue(
    bookingFieldResponseValue: string | number,
    eventTypeBookingFieldOptions: string[]
  ): boolean {
    if (eventTypeBookingFieldOptions.length === 0) {
      // note(Lauris): If no options defined, cannot validate against them, so pass.
      return true;
    }
    return eventTypeBookingFieldOptions.some((val) => val === String(bookingFieldResponseValue));

View on GitHub (pinned to 176037d0af)

Solutions

Coerce the value to the expected JS type before submitting (boolean -> true/false, array for multiselect/checkbox).
Re-fetch the event type to confirm each field's type and align payload accordingly.
Add a serialization layer that respects JSON types rather than form-encoded strings.

Example fix

// before — boolean field sent as string
const responses = { optIn: 'true' };
// after
const responses = { optIn: true };

Defensive patterns

Strategy: type-guard

Validate before calling

function coerceForType(value: unknown, type: string) {
  switch (type) {
    case 'boolean': return typeof value === 'boolean' ? value : Boolean(value);
    case 'number': return typeof value === 'number' ? value : Number(value);
    case 'multiselect': case 'checkbox': return Array.isArray(value) ? value : [value];
    default: return typeof value === 'string' ? value : String(value);
  }
}

Type guard

function matchesExpected(value: unknown, type: string): boolean {
  switch (type) {
    case 'boolean': return typeof value === 'boolean';
    case 'number': return typeof value === 'number';
    case 'select': case 'radio': return typeof value === 'string' || typeof value === 'number';
    case 'multiselect': case 'checkbox': return Array.isArray(value);
    case 'url': return typeof value === 'string';
    default: return true;
  }
}

Try / catch

try { await client.post('/v2/bookings', body); }
catch (e) {
  if (e.status === 400 && /Invalid type for booking field/.test(e.message)) { /* coerce value, retry */ }
  else throw e;
}

Prevention

Send JSON with native types (not form-encoded strings)
Coerce form values to proper types before submission
Map field type to expected JS type in a shared util

When it happens

Trigger: A booking field response has a runtime type that does not match the expected type for the field — e.g. sending a string for a boolean field, a number for an array field, or an object for a string field.

Common situations: Loosely-typed JSON payloads from integrations; sending 'true' (string) instead of true (boolean) for boolean fields; sending a single value instead of an array for multiselect/checkbox; form serialization converting types.

Related errors

AI-assisted analysis of calcom/cal.diy@176037d0af (2026-08-12). Data as JSON: /api/errors/869621fb3bdd510f. Report an issue: GitHub.