Function processDecoratorParameters

packages/decorators/src/utils.ts:67–89

(params: Dictionary)

 * @internal
 */
export function processDecoratorParameters<T>(params: Dictionary): T {
  const keys = Object.keys(params);
  const values = Object.values(params);

  if (!Utils.isPlainObject(values[0])) {
    const lastKey = keys[keys.length - 1];
    const last = params[lastKey];
    delete params[lastKey];

    return { ...last, ...params };
  }

  // validate only first parameter is used if its an option object
  const empty = (v: unknown) => v == null || (Utils.isPlainObject(v) && !Utils.hasObjectKeys(v));
  if (values.slice(1).some(v => !empty(v))) {
    throw new Error(
      'Mixing first decorator parameter as options object with other parameters is forbidden. ' +
        'If you want to use the options parameter at first position, provide all options inside it.',
    );
  }

  return values[0] as T;
}

/**
 * Validate there is only one property decorator. This disallows using `@Property()` together with e.g. `@ManyToOne()`