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'use strict';
const CastError = require('../error/cast');
/** * Given a value, cast it to a string, or throw a `CastError` if the value * cannot be casted. `null` and `undefined` are considered valid. * * @param {Any} value * @param {String} [path] optional the path to set on the CastError * @return {string|null|undefined} * @throws {CastError} * @api private */
module.exports = function castString(value, path) {  // If null or undefined  if (value == null) {    return value;  }
  // handle documents being passed  if (value._id && typeof value._id === 'string') {    return value._id;  }
  // Re: gh-647 and gh-3030, we're ok with casting using `toString()`  // **unless** its the default Object.toString, because "[object Object]"  // doesn't really qualify as useful data  if (value.toString &&      value.toString !== Object.prototype.toString &&      !Array.isArray(value)) {    return value.toString();  }
  throw new CastError('string', value, path);};