Automattic/mongoose · error · MongooseError

Invalid select: select only takes 1 argument

Error message

Invalid select: select only takes 1 argument

What it means

Error "Invalid select: select only takes 1 argument" thrown in Automattic/mongoose.

Source

Thrown at lib/query.js:1133

 *     query.select({ a: 1, b: 1 }).select({ b: 0 }); // selection is now { a: 1 }
 *     query.select({ a: 0, b: 0 }).select({ b: 1 }); // selection is now { a: 0 }
 *
 *
 * @method select
 * @memberOf Query
 * @instance
 * @param {object|string|Array<string>} arg
 * @return {Query} this
 * @see SchemaType https://mongoosejs.com/docs/api/schematype.html
 * @api public
 */

Query.prototype.select = function select() {
  let arg = arguments[0];
  if (!arg) return this;

  if (arguments.length !== 1) {
    throw new MongooseError('Invalid select: select only takes 1 argument');
  }

  this._validate('select');

  const fields = this._fields || (this._fields = {});
  const userProvidedFields = this._userProvidedFields || (this._userProvidedFields = {});
  let sanitizeProjection = undefined;
  if (this.model != null && utils.hasUserDefinedProperty(this.model.db.options, 'sanitizeProjection')) {
    sanitizeProjection = this.model.db.options.sanitizeProjection;
  } else if (this.model != null && utils.hasUserDefinedProperty(this.model.base.options, 'sanitizeProjection')) {
    sanitizeProjection = this.model.base.options.sanitizeProjection;
  } else {
    sanitizeProjection = this._mongooseOptions.sanitizeProjection;
  }

  function sanitizeValue(value) {
    return typeof value === 'string' && sanitizeProjection ? value = 1 : value;
  }

View on GitHub (pinned to 49cdab0136)

When it happens

Trigger: Thrown at lib/query.js:1133 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of Automattic/mongoose@49cdab0136 (2026-08-21). Data as JSON: /api/errors/eca9e4c330f01e40. Report an issue: GitHub.