mongoose/lib/query.js

Mongoose MongoDB ODM

/*!
 * Module dependencies.
 */

var CastError = require('./error/cast');
var ObjectParameterError = require('./error/objectParameter');
var PromiseProvider = require('./promise_provider');
var QueryCursor = require('./cursor/QueryCursor');
var QueryStream = require('./querystream');
var cast = require('./cast');
var castUpdate = require('./services/query/castUpdate');
var hasDollarKeys = require('./services/query/hasDollarKeys');
var helpers = require('./queryhelpers');
var isInclusive = require('./services/projection/isInclusive');
var mquery = require('mquery');
var readPref = require('./drivers').ReadPreference;
var selectPopulatedFields = require('./services/query/selectPopulatedFields');
var setDefaultsOnInsert = require('./services/setDefaultsOnInsert');
var slice = require('sliced');
var updateValidators = require('./services/updateValidators');
var util = require('util');
var utils = require('./utils');

/**
 * Query constructor used for building queries.
 *
 * ####Example:
 *
 *     var query = new Query();
 *     query.setOptions({ lean : true });
 *     query.collection(model.collection);
 *     query.where('age').gte(21).exec(callback);
 *
 * @param {Object} [options]
 * @param {Object} [model]
 * @param {Object} [conditions]
 * @param {Object} [collection] Mongoose collection
 * @api private
 */

function Query(conditions, options, model, collection) {
  // this stuff is for dealing with custom queries created by #toConstructor
  if (!this._mongooseOptions) {
    this._mongooseOptions = {};
  }

  // this is the case where we have a CustomQuery, we need to check if we got
  // options passed in, and if we did, merge them in
  if (options) {
    var keys = Object.keys(options);
    for (var i = 0; i < keys.length; ++i) {
      var k = keys[i];
      this._mongooseOptions[k] = options[k];
    }
  }

  if (collection) {
    this.mongooseCollection = collection;
  }

  if (model) {
    this.model = model;
    this.schema = model.schema;
  }

  // this is needed because map reduce returns a model that can be queried, but
  // all of the queries on said model should be lean
  if (this.model && this.model._mapreduce) {
    this.lean();
  }

  // inherit mquery
  mquery.call(this, this.mongooseCollection, options);

  if (conditions) {
    this.find(conditions);
  }

  this.options = this.options || {};
  if (this.schema != null && this.schema.options.collation != null) {
    this.options.collation = this.schema.options.collation;
  }

  if (this.schema) {
    var kareemOptions = {
      useErrorHandlers: true,
      numCallbackParams: 1,
      nullResultByDefault: true
    };
    this._count = this.model.hooks.createWrapper('count',
        Query.prototype._count, this, kareemOptions);
    this._execUpdate = this.model.hooks.createWrapper('update',
        Query.prototype._execUpdate, this, kareemOptions);
    this._find = this.model.hooks.createWrapper('find',
        Query.prototype._find, this, kareemOptions);
    this._findOne = this.model.hooks.createWrapper('findOne',
        Query.prototype._findOne, this, kareemOptions);
    this._findOneAndRemove = this.model.hooks.createWrapper('findOneAndRemove',
        Query.prototype._findOneAndRemove, this, kareemOptions);
    this._findOneAndUpdate = this.model.hooks.createWrapper('findOneAndUpdate',
        Query.prototype._findOneAndUpdate, this, kareemOptions);
    this._replaceOne = this.model.hooks.createWrapper('replaceOne',
        Query.prototype._replaceOne, this, kareemOptions);
    this._updateMany = this.model.hooks.createWrapper('updateMany',
        Query.prototype._updateMany, this, kareemOptions);
    this._updateOne = this.model.hooks.createWrapper('updateOne',
        Query.prototype._updateOne, this, kareemOptions);
  }
}

/*!
 * inherit mquery
 */

Query.prototype = new mquery;
Query.prototype.constructor = Query;
Query.base = mquery.prototype;

/**
 * Flag to opt out of using `$geoWithin`.
 *
 *     mongoose.Query.use$geoWithin = false;
 *
 * MongoDB 2.4 deprecated the use of `$within`, replacing it with `$geoWithin`. Mongoose uses `$geoWithin` by default (which is 100% backward compatible with $within). If you are running an older version of MongoDB, set this flag to `false` so your `within()` queries continue to work.
 *
 * @see http://docs.mongodb.org/manual/reference/operator/geoWithin/
 * @default true
 * @property use$geoWithin
 * @memberOf Query
 * @receiver Query
 * @api public
 */

Query.use$geoWithin = mquery.use$geoWithin;

/**
 * Converts this query to a customized, reusable query constructor with all arguments and options retained.
 *
 * ####Example
 *
 *     // Create a query for adventure movies and read from the primary
 *     // node in the replica-set unless it is down, in which case we'll
 *     // read from a secondary node.
 *     var query = Movie.find({ tags: 'adventure' }).read('primaryPreferred');
 *
 *     // create a custom Query constructor based off these settings
 *     var Adventure = query.toConstructor();
 *
 *     // Adventure is now a subclass of mongoose.Query and works the same way but with the
 *     // default query parameters and options set.
 *     Adventure().exec(callback)
 *
 *     // further narrow down our query results while still using the previous settings
 *     Adventure().where({ name: /^Life/ }).exec(callback);
 *
 *     // since Adventure is a stand-alone constructor we can also add our own
 *     // helper methods and getters without impacting global queries
 *     Adventure.prototype.startsWith = function (prefix) {
 *       this.where({ name: new RegExp('^' + prefix) })
 *       return this;
 *     }
 *     Object.defineProperty(Adventure.prototype, 'highlyRated', {
 *       get: function () {
 *         this.where({ rating: { $gt: 4.5 }});
 *         return this;
 *       }
 *     })
 *     Adventure().highlyRated.startsWith('Life').exec(callback)
 *
 * New in 3.7.3
 *
 * @return {Query} subclass-of-Query
 * @api public
 */

Query.prototype.toConstructor = function toConstructor() {
  var model = this.model;
  var coll = this.mongooseCollection;

  var CustomQuery = function(criteria, options) {
    if (!(this instanceof CustomQuery)) {
      return new CustomQuery(criteria, options);
    }
    this._mongooseOptions = utils.clone(p._mongooseOptions);
    Query.call(this, criteria, options || null, model, coll);
  };

  util.inherits(CustomQuery, Query);

  // set inherited defaults
  var p = CustomQuery.prototype;

  p.options = {};

  p.setOptions(this.options);

  p.op = this.op;
  p._conditions = utils.clone(this._conditions, { retainKeyOrder: true });
  p._fields = utils.clone(this._fields);
  p._update = utils.clone(this._update, {
    flattenDecimals: false,
    retainKeyOrder: true
  });
  p._path = this._path;
  p._distinct = this._distinct;
  p._collection = this._collection;
  p._mongooseOptions = this._mongooseOptions;

  return CustomQuery;
};

/**
 * Specifies a javascript function or expression to pass to MongoDBs query system.
 *
 * ####Example
 *
 *     query.$where('this.comments.length === 10 || this.name.length === 5')
 *
 *     // or
 *
 *     query.$where(function () {
 *       return this.comments.length === 10 || this.name.length === 5;
 *     })
 *
 * ####NOTE:
 *
 * Only use `$where` when you have a condition that cannot be met using other MongoDB operators like `$lt`.
 * **Be sure to read about all of [its caveats](http://docs.mongodb.org/manual/reference/operator/where/) before using.**
 *
 * @see $where http://docs.mongodb.org/manual/reference/operator/where/
 * @method $where
 * @param {String|Function} js javascript string or function
 * @return {Query} this
 * @memberOf Query
 * @method $where
 * @api public
 */

/**
 * Specifies a `path` for use with chaining.
 *
 * ####Example
 *
 *     // instead of writing:
 *     User.find({age: {$gte: 21, $lte: 65}}, callback);
 *
 *     // we can instead write:
 *     User.where('age').gte(21).lte(65);
 *
 *     // passing query conditions is permitted
 *     User.find().where({ name: 'vonderful' })
 *
 *     // chaining
 *     User
 *     .where('age').gte(21).lte(65)
 *     .where('name', /^vonderful/i)
 *     .where('friends').slice(10)
 *     .exec(callback)
 *
 * @method where
 * @memberOf Query
 * @param {String|Object} [path]
 * @param {any} [val]
 * @return {Query} this
 * @api public
 */

Query.prototype.slice = function() {
  if (arguments.length === 0) {
    return this;
  }

  this._validate('slice');

  var path;
  var val;

  if (arguments.length === 1) {
    var arg = arguments[0];
    if (typeof arg === 'object' && !Array.isArray(arg)) {
      var keys = Object.keys(arg);
      var numKeys = keys.length;
      for (var i = 0; i < numKeys; ++i) {
        this.slice(keys[i], arg[keys[i]]);
      }
      return this;
    }
    this._ensurePath('slice');
    path = this._path;
    val = arguments[0];
  } else if (arguments.length === 2) {
    if ('number' === typeof arguments[0]) {
      this._ensurePath('slice');
      path = this._path;
      val = slice(arguments);
    } else {
      path = arguments[0];
      val = arguments[1];
    }
  } else if (arguments.length === 3) {
    path = arguments[0];
    val = slice(arguments, 1);
  }

  var p = {};
  p[path] = { $slice: val };
  return this.select(p);
};


/**
 * Specifies the complementary comparison value for paths specified with `where()`
 *
 * ####Example
 *
 *     User.where('age').equals(49);
 *
 *     // is the same as
 *
 *     User.where('age', 49);
 *
 * @method equals
 * @memberOf Query
 * @param {Object} val
 * @return {Query} this
 * @api public
 */

/**
 * Specifies arguments for an `$or` condition.
 *
 * ####Example
 *
 *     query.or([{ color: 'red' }, { status: 'emergency' }])
 *
 * @see $or http://docs.mongodb.org/manual/reference/operator/or/
 * @method or
 * @memberOf Query
 * @param {Array} array array of conditions
 * @return {Query} this
 * @api public
 */

/**
 * Specifies arguments for a `$nor` condition.
 *
 * ####Example
 *
 *     query.nor([{ color: 'green' }, { status: 'ok' }])
 *
 * @see $nor http://docs.mongodb.org/manual/reference/operator/nor/
 * @method nor
 * @memberOf Query
 * @param {Array} array array of conditions
 * @return {Query} this
 * @api public
 */

/**
 * Specifies arguments for a `$and` condition.
 *
 * ####Example
 *
 *     query.and([{ color: 'green' }, { status: 'ok' }])
 *
 * @method and
 * @memberOf Query
 * @see $and http://docs.mongodb.org/manual/reference/operator/and/
 * @param {Array} array array of conditions
 * @return {Query} this
 * @api public
 */

/**
 * Specifies a $gt query condition.
 *
 * When called with one argument, the most recent path passed to `where()` is used.
 *
 * ####Example
 *
 *     Thing.find().where('age').gt(21)
 *
 *     // or
 *     Thing.find().gt('age', 21)
 *
 * @method gt
 * @memberOf Query
 * @param {String} [path]
 * @param {Number} val
 * @see $gt http://docs.mongodb.org/manual/reference/operator/gt/
 * @api public
 */

/**
 * Specifies a $gte query condition.
 *
 * When called with one argument, the most recent path passed to `where()` is used.
 *
 * @method gte
 * @memberOf Query
 * @param {String} [path]
 * @param {Number} val
 * @see $gte http://docs.mongodb.org/manual/reference/operator/gte/
 * @api public
 */

/**
 * Specifies a $lt query condition.
 *
 * When called with one argument, the most recent path passed to `where()` is used.
 *
 * @method lt
 * @memberOf Query
 * @param {String} [path]
 * @param {Number} val
 * @see $lt http://docs.mongodb.org/manual/reference/operator/lt/
 * @api public
 */

/**
 * Specifies a $lte query condition.
 *
 * When called with one argument, the most recent path passed to `where()` is used.
 *
 * @method lte
 * @see $lte http://docs.mongodb.org/manual/reference/operator/lte/
 * @memberOf Query
 * @param {String} [path]
 * @param {Number} val
 * @api public
 */

/**
 * Specifies a $ne query condition.
 *
 * When called with one argument, the most recent path passed to `where()` is used.
 *
 * @see $ne http://docs.mongodb.org/manual/reference/operator/ne/
 * @method ne
 * @memberOf Query
 * @param {String} [path]
 * @param {Number} val
 * @api public
 */

/**
 * Specifies an $in query condition.
 *
 * When called with one argument, the most recent path passed to `where()` is used.
 *
 * @see $in http://docs.mongodb.org/manual/reference/operator/in/
 * @method in
 * @memberOf Query
 * @param {String} [path]
 * @param {Number} val
 * @api public
 */

/**
 * Specifies an $nin query condition.
 *
 * When called with one argument, the most recent path passed to `where()` is used.
 *
 * @see $nin http://docs.mongodb.org/manual/reference/operator/nin/
 * @method nin
 * @memberOf Query
 * @param {String} [path]
 * @param {Number} val
 * @api public
 */

/**
 * Specifies an $all query condition.
 *
 * When called with one argument, the most recent path passed to `where()` is used.
 *
 * @see $all http://docs.mongodb.org/manual/reference/operator/all/
 * @method all
 * @memberOf Query
 * @param {String} [path]
 * @param {Number} val
 * @api public
 */

/**
 * Specifies a $size query condition.
 *
 * When called with one argument, the most recent path passed to `where()` is used.
 *
 * ####Example
 *
 *     MyModel.where('tags').size(0).exec(function (err, docs) {
 *       if (err) return handleError(err);
 *
 *       assert(Array.isArray(docs));
 *       console.log('documents with 0 tags', docs);
 *     })
 *
 * @see $size http://docs.mongodb.org/manual/reference/operator/size/
 * @method size
 * @memberOf Query
 * @param {String} [path]
 * @param {Number} val
 * @api public
 */

/**
 * Specifies a $regex query condition.
 *
 * When called with one argument, the most recent path passed to `where()` is used.
 *
 * @see $regex http://docs.mongodb.org/manual/reference/operator/regex/
 * @method regex
 * @memberOf Query
 * @param {String} [path]
 * @param {String|RegExp} val
 * @api public
 */

/**
 * Specifies a $maxDistance query condition.
 *
 * When called with one argument, the most recent path passed to `where()` is used.
 *
 * @see $maxDistance http://docs.mongodb.org/manual/reference/operator/maxDistance/
 * @method maxDistance
 * @memberOf Query
 * @param {String} [path]
 * @param {Number} val
 * @api public
 */

/**
 * Specifies a `$mod` condition, filters documents for documents whose
 * `path` property is a number that is equal to `remainder` modulo `divisor`.
 *
 * ####Example
 *
 *     // All find products whose inventory is odd
 *     Product.find().mod('inventory', [2, 1]);
 *     Product.find().where('inventory').mod([2, 1]);
 *     // This syntax is a little strange, but supported.
 *     Product.find().where('inventory').mod(2, 1);
 *
 * @method mod
 * @memberOf Query
 * @param {String} [path]
 * @param {Array} val must be of length 2, first element is `divisor`, 2nd element is `remainder`.
 * @return {Query} this
 * @see $mod http://docs.mongodb.org/manual/reference/operator/mod/
 * @api public
 */

Query.prototype.mod = function() {
  var val;
  var path;

  if (arguments.length === 1) {
    this._ensurePath('mod');
    val = arguments[0];
    path = this._path;
  } else if (arguments.length === 2 && !Array.isArray(arguments[1])) {
    this._ensurePath('mod');
    val = slice(arguments);
    path = this._path;
  } else if (arguments.length === 3) {
    val = slice(arguments, 1);
    path = arguments[0];
  } else {
    val = arguments[1];
    path = arguments[0];
  }

  var conds = this._conditions[path] || (this._conditions[path] = {});
  conds.$mod = val;
  return this;
};

/**
 * Specifies an `$exists` condition
 *
 * ####Example
 *
 *     // { name: { $exists: true }}
 *     Thing.where('name').exists()
 *     Thing.where('name').exists(true)
 *     Thing.find().exists('name')
 *
 *     // { name: { $exists: false }}
 *     Thing.where('name').exists(false);
 *     Thing.find().exists('name', false);
 *
 * @method exists
 * @memberOf Query
 * @param {String} [path]
 * @param {Number} val
 * @return {Query} this
 * @see $exists http://docs.mongodb.org/manual/reference/operator/exists/
 * @api public
 */

/**
 * Specifies an `$elemMatch` condition
 *
 * ####Example
 *
 *     query.elemMatch('comment', { author: 'autobot', votes: {$gte: 5}})
 *
 *     query.where('comment').elemMatch({ author: 'autobot', votes: {$gte: 5}})
 *
 *     query.elemMatch('comment', function (elem) {
 *       elem.where('author').equals('autobot');
 *       elem.where('votes').gte(5);
 *     })
 *
 *     query.where('comment').elemMatch(function (elem) {
 *       elem.where({ author: 'autobot' });
 *       elem.where('votes').gte(5);
 *     })
 *
 * @method elemMatch
 * @memberOf Query
 * @param {String|Object|Function} path
 * @param {Object|Function} criteria
 * @return {Query} this
 * @see $elemMatch http://docs.mongodb.org/manual/reference/operator/elemMatch/
 * @api public
 */

/**
 * Defines a `$within` or `$geoWithin` argument for geo-spatial queries.
 *
 * ####Example
 *
 *     query.where(path).within().box()
 *     query.where(path).within().circle()
 *     query.where(path).within().geometry()
 *
 *     query.where('loc').within({ center: [50,50], radius: 10, unique: true, spherical: true });
 *     query.where('loc').within({ box: [[40.73, -73.9], [40.7, -73.988]] });
 *     query.where('loc').within({ polygon: [[],[],[],[]] });
 *
 *     query.where('loc').within([], [], []) // polygon
 *     query.where('loc').within([], []) // box
 *     query.where('loc').within({ type: 'LineString', coordinates: [...] }); // geometry
 *
 * **MUST** be used after `where()`.
 *
 * ####NOTE:
 *
 * As of Mongoose 3.7, `$geoWithin` is always used for queries. To change this behavior, see [Query.use$geoWithin](#query_Query-use%2524geoWithin).
 *
 * ####NOTE:
 *
 * In Mongoose 3.7, `within` changed from a getter to a function. If you need the old syntax, use [this](https://github.com/ebensing/mongoose-within).
 *
 * @method within
 * @see $polygon http://docs.mongodb.org/manual/reference/operator/polygon/
 * @see $box http://docs.mongodb.org/manual/reference/operator/box/
 * @see $geometry http://docs.mongodb.org/manual/reference/operator/geometry/
 * @see $center http://docs.mongodb.org/manual/reference/operator/center/
 * @see $centerSphere http://docs.mongodb.org/manual/reference/operator/centerSphere/
 * @memberOf Query
 * @return {Query} this
 * @api public
 */

/**
 * Specifies a $slice projection for an array.
 *
 * ####Example
 *
 *     query.slice('comments', 5)
 *     query.slice('comments', -5)
 *     query.slice('comments', [10, 5])
 *     query.where('comments').slice(5)
 *     query.where('comments').slice([-10, 5])
 *
 * @method slice
 * @memberOf Query
 * @param {String} [path]
 * @param {Number} val number/range of elements to slice
 * @return {Query} this
 * @see mongodb http://www.mongodb.org/display/DOCS/Retrieving+a+Subset+of+Fields#RetrievingaSubsetofFields-RetrievingaSubrangeofArrayElements
 * @see $slice http://docs.mongodb.org/manual/reference/projection/slice/#prj._S_slice
 * @api public
 */

/**
 * Specifies the maximum number of documents the query will return.
 *
 * ####Example
 *
 *     query.limit(20)
 *
 * ####Note
 *
 * Cannot be used with `distinct()`
 *
 * @method limit
 * @memberOf Query
 * @param {Number} val
 * @api public
 */

/**
 * Specifies the number of documents to skip.
 *
 * ####Example
 *
 *     query.skip(100).limit(20)
 *
 * ####Note
 *
 * Cannot be used with `distinct()`
 *
 * @method skip
 * @memberOf Query
 * @param {Number} val
 * @see cursor.skip http://docs.mongodb.org/manual/reference/method/cursor.skip/
 * @api public
 */

/**
 * Specifies the maxScan option.
 *
 * ####Example
 *
 *     query.maxScan(100)
 *
 * ####Note
 *
 * Cannot be used with `distinct()`
 *
 * @method maxScan
 * @memberOf Query
 * @param {Number} val
 * @see maxScan http://docs.mongodb.org/manual/reference/operator/maxScan/
 * @api public
 */

/**
 * Specifies the batchSize option.
 *
 * ####Example
 *
 *     query.batchSize(100)
 *
 * ####Note
 *
 * Cannot be used with `distinct()`
 *
 * @method batchSize
 * @memberOf Query
 * @param {Number} val
 * @see batchSize http://docs.mongodb.org/manual/reference/method/cursor.batchSize/
 * @api public
 */

/**
 * Specifies the `comment` option.
 *
 * ####Example
 *
 *     query.comment('login query')
 *
 * ####Note
 *
 * Cannot be used with `distinct()`
 *
 * @method comment
 * @memberOf Query
 * @param {Number} val
 * @see comment http://docs.mongodb.org/manual/reference/operator/comment/
 * @api public
 */

/**
 * Specifies this query as a `snapshot` query.
 *
 * ####Example
 *
 *     query.snapshot() // true
 *     query.snapshot(true)
 *     query.snapshot(false)
 *
 * ####Note
 *
 * Cannot be used with `distinct()`
 *
 * @method snapshot
 * @memberOf Query
 * @see snapshot http://docs.mongodb.org/manual/reference/operator/snapshot/
 * @return {Query} this
 * @api public
 */

/**
 * Sets query hints.
 *
 * ####Example
 *
 *     query.hint({ indexA: 1, indexB: -1})
 *
 * ####Note
 *
 * Cannot be used with `distinct()`
 *
 * @method hint
 * @memberOf Query
 * @param {Object} val a hint object
 * @return {Query} this
 * @see $hint http://docs.mongodb.org/manual/reference/operator/hint/
 * @api public
 */

/**
 * Specifies which document fields to include or exclude (also known as the query "projection")
 *
 * When using string syntax, prefixing a path with `-` will flag that path as excluded. When a path does not have the `-` prefix, it is included. Lastly, if a path is prefixed with `+`, it forces inclusion of the path, which is useful for paths excluded at the [schema level](/docs/api.html#schematype_SchemaType-select).
 *
 * A projection _must_ be either inclusive or exclusive. In other words, you must
 * either list the fields to include (which excludes all others), or list the fields
 * to exclude (which implies all other fields are included). The [`_id` field is the only exception because MongoDB includes it by default](https://docs.mongodb.com/manual/tutorial/project-fields-from-query-results/#suppress-id-field).
 *
 * ####Example
 *
 *     // include a and b, exclude other fields
 *     query.select('a b');
 *
 *     // exclude c and d, include other fields
 *     query.select('-c -d');
 *
 *     // or you may use object notation, useful when
 *     // you have keys already prefixed with a "-"
 *     query.select({ a: 1, b: 1 });
 *     query.select({ c: 0, d: 0 });
 *
 *     // force inclusion of field excluded at schema level
 *     query.select('+path')
 *
 * @method select
 * @memberOf Query
 * @param {Object|String} arg
 * @return {Query} this
 * @see SchemaType
 * @api public
 */

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

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

  this._validate('select');

  var fields = this._fields || (this._fields = {});
  var userProvidedFields = this._userProvidedFields || (this._userProvidedFields = {});
  var type = typeof arg;

  if (('string' == type || Object.prototype.toString.call(arg) === '[object Arguments]') &&
    'number' == typeof arg.length || Array.isArray(arg)) {
    if ('string' == type)
      arg = arg.split(/\s+/);

    for (i = 0, len = arg.length; i < len; ++i) {
      var field = arg[i];
      if (!field) continue;
      var include = '-' == field[0] ? 0 : 1;
      if (include === 0) field = field.substring(1);
      fields[field] = include;
      userProvidedFields[field] = include;
    }

    return this;
  }

  if (utils.isObject(arg)) {
    var keys = Object.keys(arg);
    for (i = 0; i < keys.length; ++i) {
      fields[keys[i]] = arg[keys[i]];
      userProvidedFields[keys[i]] = arg[keys[i]];
    }
    return this;
  }

  throw new TypeError('Invalid select() argument. Must be string or object.');
};

/**
 * _DEPRECATED_ Sets the slaveOk option.
 *
 * **Deprecated** in MongoDB 2.2 in favor of [read preferences](#query_Query-read).
 *
 * ####Example:
 *
 *     query.slaveOk() // true
 *     query.slaveOk(true)
 *     query.slaveOk(false)
 *
 * @method slaveOk
 * @memberOf Query
 * @deprecated use read() preferences instead if on mongodb >= 2.2
 * @param {Boolean} v defaults to true
 * @see mongodb http://docs.mongodb.org/manual/applications/replication/#read-preference
 * @see slaveOk http://docs.mongodb.org/manual/reference/method/rs.slaveOk/
 * @see read() #query_Query-read
 * @return {Query} this
 * @api public
 */

/**
 * Determines the MongoDB nodes from which to read.
 *
 * ####Preferences:
 *
 *     primary - (default) Read from primary only. Operations will produce an error if primary is unavailable. Cannot be combined with tags.
 *     secondary            Read from secondary if available, otherwise error.
 *     primaryPreferred     Read from primary if available, otherwise a secondary.
 *     secondaryPreferred   Read from a secondary if available, otherwise read from the primary.
 *     nearest              All operations read from among the nearest candidates, but unlike other modes, this option will include both the primary and all secondaries in the random selection.
 *
 * Aliases
 *
 *     p   primary
 *     pp  primaryPreferred
 *     s   secondary
 *     sp  secondaryPreferred
 *     n   nearest
 *
 * ####Example:
 *
 *     new Query().read('primary')
 *     new Query().read('p')  // same as primary
 *
 *     new Query().read('primaryPreferred')
 *     new Query().read('pp') // same as primaryPreferred
 *
 *     new Query().read('secondary')
 *     new Query().read('s')  // same as secondary
 *
 *     new Query().read('secondaryPreferred')
 *     new Query().read('sp') // same as secondaryPreferred
 *
 *     new Query().read('nearest')
 *     new Query().read('n')  // same as nearest
 *
 *     // read from secondaries with matching tags
 *     new Query().read('s', [{ dc:'sf', s: 1 },{ dc:'ma', s: 2 }])
 *
 * Read more about how to use read preferrences [here](http://docs.mongodb.org/manual/applications/replication/#read-preference) and [here](http://mongodb.github.com/node-mongodb-native/driver-articles/anintroductionto1_1and2_2.html#read-preferences).
 *
 * @method read
 * @memberOf Query
 * @param {String} pref one of the listed preference options or aliases
 * @param {Array} [tags] optional tags for this query
 * @see mongodb http://docs.mongodb.org/manual/applications/replication/#read-preference
 * @see driver http://mongodb.github.com/node-mongodb-native/driver-articles/anintroductionto1_1and2_2.html#read-preferences
 * @return {Query} this
 * @api public
 */

Query.prototype.read = function read(pref, tags) {
  // first cast into a ReadPreference object to support tags
  var read = readPref.call(readPref, pref, tags);
  this.options.readPreference = read;
  return this;
};

/**
 * Merges another Query or conditions object into this one.
 *
 * When a Query is passed, conditions, field selection and options are merged.
 *
 * New in 3.7.0
 *
 * @method merge
 * @memberOf Query
 * @param {Query|Object} source
 * @return {Query} this
 */

/**
 * Sets query options. Some options only make sense for certain operations.
 *
 * ####Options:
 *
 * The following options are only for `find()`:
 * - [tailable](http://www.mongodb.org/display/DOCS/Tailable+Cursors)
 * - [sort](http://www.mongodb.org/display/DOCS/Advanced+Queries#AdvancedQueries-%7B%7Bsort(\)%7D%7D)
 * - [limit](http://www.mongodb.org/display/DOCS/Advanced+Queries#AdvancedQueries-%7B%7Blimit%28%29%7D%7D)
 * - [skip](http://www.mongodb.org/display/DOCS/Advanced+Queries#AdvancedQueries-%7B%7Bskip%28%29%7D%7D)
 * - [maxscan](https://docs.mongodb.org/v3.2/reference/operator/meta/maxScan/#metaOp._S_maxScan)
 * - [batchSize](http://www.mongodb.org/display/DOCS/Advanced+Queries#AdvancedQueries-%7B%7BbatchSize%28%29%7D%7D)
 * - [comment](http://www.mongodb.org/display/DOCS/Advanced+Queries#AdvancedQueries-%24comment)
 * - [snapshot](http://www.mongodb.org/display/DOCS/Advanced+Queries#AdvancedQueries-%7B%7Bsnapshot%28%29%7D%7D)
 * - [readPreference](http://docs.mongodb.org/manual/applications/replication/#read-preference)
 * - [hint](http://www.mongodb.org/display/DOCS/Advanced+Queries#AdvancedQueries-%24hint)
 *
 * The following options are only for `update()`, `updateOne()`, `updateMany()`, `replaceOne()`, `findOneAndUpdate()`, and `findByIdAndUpdate()`:
 * - [upsert](https://docs.mongodb.com/manual/reference/method/db.collection.update/)
 * - [writeConcern](https://docs.mongodb.com/manual/reference/method/db.collection.update/)
 *
 * The following options are only for `find()`, `findOne()`, `findById()`, `findOneAndUpdate()`, and `findByIdAndUpdate()`:
 * - [lean](./api.html#query_Query-lean)
 *
 * The following options are only for all operations **except** `update()`, `updateOne()`, `updateMany()`, `remove()`, `deleteOne()`, and `deleteMany()`:
 * - [maxTimeMS](https://docs.mongodb.com/manual/reference/operator/meta/maxTimeMS/)
 *
 * The following options are for all operations:
 * - [collation](https://docs.mongodb.com/manual/reference/collation/)
 *
 * @param {Object} options
 * @api public
 */

Query.prototype.setOptions = function(options, overwrite) {
  // overwrite is only for internal use
  if (overwrite) {
    // ensure that _mongooseOptions & options are two different objects
    this._mongooseOptions = (options && utils.clone(options)) || {};
    this.options = options || {};

    if ('populate' in options) {
      this.populate(this._mongooseOptions);
    }
    return this;
  }

  if (options == null) {
    return this;
  }

  if (Array.isArray(options.populate)) {
    var populate = options.populate;
    delete options.populate;
    var _numPopulate = populate.length;
    for (var i = 0; i < _numPopulate; ++i) {
      this.populate(populate[i]);
    }
  }

  return Query.base.setOptions.call(this, options);
};

/**
 * Returns the current query conditions as a JSON object.
 *
 * ####Example:
 *
 *     var query = new Query();
 *     query.find({ a: 1 }).where('b').gt(2);
 *     query.getQuery(); // { a: 1, b: { $gt: 2 } }
 *
 * @return {Object} current query conditions
 * @api public
 */

Query.prototype.getQuery = function() {
  return this._conditions;
};

/**
 * Returns the current update operations as a JSON object.
 *
 * ####Example:
 *
 *     var query = new Query();
 *     query.update({}, { $set: { a: 5 } });
 *     query.getUpdate(); // { $set: { a: 5 } }
 *
 * @return {Object} current update operations
 * @api public
 */

Query.prototype.getUpdate = function() {
  return this._update;
};

/**
 * Returns fields selection for this query.
 *
 * @method _fieldsForExec
 * @return {Object}
 * @api private
 * @receiver Query
 */

/**
 * Return an update document with corrected $set operations.
 *
 * @method _updateForExec
 * @api private
 * @receiver Query
 */

Query.prototype._updateForExec = function() {
  var update = utils.clone(this._update, {
    retainKeyOrder: true,
    transform: false,
    depopulate: true
  });
  var ops = Object.keys(update);
  var i = ops.length;
  var ret = {};

  while (i--) {
    var op = ops[i];

    if (this.options.overwrite) {
      ret[op] = update[op];
      continue;
    }

    if ('$' !== op[0]) {
      // fix up $set sugar
      if (!ret.$set) {
        if (update.$set) {
          ret.$set = update.$set;
        } else {
          ret.$set = {};
        }
      }
      ret.$set[op] = update[op];
      ops.splice(i, 1);
      if (!~ops.indexOf('$set')) ops.push('$set');
    } else if ('$set' === op) {
      if (!ret.$set) {
        ret[op] = update[op];
      }
    } else {
      ret[op] = update[op];
    }
  }

  return ret;
};

/**
 * Makes sure _path is set.
 *
 * @method _ensurePath
 * @param {String} method
 * @api private
 * @receiver Query
 */

/**
 * Determines if `conds` can be merged using `mquery().merge()`
 *
 * @method canMerge
 * @memberOf Query
 * @param {Object} conds
 * @return {Boolean}
 * @api private
 */

/**
 * Returns default options for this query.
 *
 * @param {Model} model
 * @api private
 */

Query.prototype._optionsForExec = function(model) {
  var options = Query.base._optionsForExec.call(this);

  delete options.populate;
  delete options.retainKeyOrder;
  model = model || this.model;

  if (!model) {
    return options;
  }

  if (!('safe' in options) && model.schema.options.safe) {
    options.safe = model.schema.options.safe;
  }

  if (!('readPreference' in options) && model.schema.options.read) {
    options.readPreference = model.schema.options.read;
  }

  if (options.upsert !== void 0) {
    options.upsert = !!options.upsert;
  }

  return options;
};

/**
 * Sets the lean option.
 *
 * Documents returned from queries with the `lean` option enabled are plain javascript objects, not [MongooseDocuments](#document-js). They have no `save` method, getters/setters or other Mongoose magic applied.
 *
 * ####Example:
 *
 *     new Query().lean() // true
 *     new Query().lean(true)
 *     new Query().lean(false)
 *
 *     Model.find().lean().exec(function (err, docs) {
 *       docs[0] instanceof mongoose.Document // false
 *     });
 *
 * This is a [great](https://groups.google.com/forum/#!topic/mongoose-orm/u2_DzDydcnA/discussion) option in high-performance read-only scenarios, especially when combined with [stream](#query_Query-stream).
 *
 * @param {Boolean|Object} bool defaults to true
 * @return {Query} this
 * @api public
 */

Query.prototype.lean = function(v) {
  this._mongooseOptions.lean = arguments.length ? v : true;
  return this;
};

/**
 * Gets/sets the error flag on this query. If this flag is not null or
 * undefined, the `exec()` promise will reject without executing.
 *
 * ####Example:
 *
 *     Query().error(); // Get current error value
 *     Query().error(null); // Unset the current error
 *     Query().error(new Error('test')); // `exec()` will resolve with test
 *     Schema.pre('find', function() {
 *       if (!this.getQuery().userId) {
 *         this.error(new Error('Not allowed to query without setting userId'));
 *       }
 *     });
 *
 * Note that query casting runs **after** hooks, so cast errors will override
 * custom errors.
 *
 * ####Example:
 *     var TestSchema = new Schema({ num: Number });
 *     var TestModel = db.model('Test', TestSchema);
 *     TestModel.find({ num: 'not a number' }).error(new Error('woops')).exec(function(error) {
 *       // `error` will be a cast error because `num` failed to cast
 *     });
 *
 * @param {Error|null} err if set, `exec()` will fail fast before sending the query to MongoDB
 * @returns {Query} this
 * @api public
 */

Query.prototype.error = function error(err) {
  if (arguments.length === 0) {
    return this._error;
  }

  this._error = err;
  return this;
};

/*!
 * ignore
 */

Query.prototype._unsetCastError = function _unsetCastError() {
  if (this._error != null && !(this._error instanceof CastError)) {
    return;
  }
  return this.error(null);
};

/**
 * Getter/setter around the current mongoose-specific options for this query
 * (populate, lean, etc.)
 *
 * @param {Object} options if specified, overwrites the current options
 * @returns {Object} the options
 * @api public
 */

Query.prototype.mongooseOptions = function(v) {
  if (arguments.length > 0) {
    this._mongooseOptions = v;
  }
  return this._mongooseOptions;
};

/*!
 * ignore
 */

Query.prototype._castConditions = function() {
  try {
    this.cast(this.model);
    this._unsetCastError();
  } catch (err) {
    this.error(err);
  }
};

/**
 * Thunk around find()
 *
 * @param {Function} [callback]
 * @return {Query} this
 * @api private
 */
Query.prototype._find = function(callback) {
  this._castConditions();

  if (this.error() != null) {
    callback(this.error());
    return this;
  }

  this._applyPaths();
  this._fields = this._castFields(this._fields);

  var fields = this._fieldsForExec();
  var mongooseOptions = this._mongooseOptions;
  var _this = this;
  var userProvidedFields = _this._userProvidedFields || {};

  var cb = function(err, docs) {
    if (err) {
      return callback(err);
    }

    if (docs.length === 0) {
      return callback(null, docs);
    }

    if (!mongooseOptions.populate) {
      return !!mongooseOptions.lean === true
          ? callback(null, docs)
          : completeMany(_this.model, docs, fields, userProvidedFields, null, callback);
    }

    var pop = helpers.preparePopulationOptionsMQ(_this, mongooseOptions);
    pop.__noPromise = true;
    _this.model.populate(docs, pop, function(err, docs) {
      if (err) return callback(err);
      return !!mongooseOptions.lean === true
          ? callback(null, docs)
          : completeMany(_this.model, docs, fields, userProvidedFields, pop, callback);
    });
  };

  var options = this._optionsForExec();
  options.fields = this._fieldsForExec();
  var filter = this._conditions;
  return this._collection.find(filter, options, cb);
};

/**
 * Finds documents.
 *
 * When no `callback` is passed, the query is not executed. When the query is executed, the result will be an array of documents.
 *
 * ####Example
 *
 *     query.find({ name: 'Los Pollos Hermanos' }).find(callback)
 *
 * @param {Object} [filter] mongodb selector
 * @param {Function} [callback]
 * @return {Query} this
 * @api public
 */

Query.prototype.find = function(conditions, callback) {
  if (typeof conditions === 'function') {
    callback = conditions;
    conditions = {};
  }

  conditions = utils.toObject(conditions);

  if (mquery.canMerge(conditions)) {
    this.merge(conditions);

    prepareDiscriminatorCriteria(this);
  } else if (conditions != null) {
    this.error(new ObjectParameterError(conditions, 'filter', 'find'));
  }

  // if we don't have a callback, then just return the query object
  if (!callback) {
    return Query.base.find.call(this);
  }

  this._find(callback);

  return this;
};

/**
 * Merges another Query or conditions object into this one.
 *
 * When a Query is passed, conditions, field selection and options are merged.
 *
 * @param {Query|Object} source
 * @return {Query} this
 */

Query.prototype.merge = function(source) {
  if (!source) {
    return this;
  }

  var opts = { retainKeyOrder: this.options.retainKeyOrder, overwrite: true };

  if (source instanceof Query) {
    // if source has a feature, apply it to ourselves

    if (source._conditions) {
      utils.merge(this._conditions, source._conditions, opts);
    }

    if (source._fields) {
      this._fields || (this._fields = {});
      utils.merge(this._fields, source._fields, opts);
    }

    if (source.options) {
      this.options || (this.options = {});
      utils.merge(this.options, source.options, opts);
    }

    if (source._update) {
      this._update || (this._update = {});
      utils.mergeClone(this._update, source._update);
    }

    if (source._distinct) {
      this._distinct = source._distinct;
    }

    return this;
  }

  // plain object
  utils.merge(this._conditions, source, opts);

  return this;
};

/*!
 * hydrates many documents
 *
 * @param {Model} model
 * @param {Array} docs
 * @param {Object} fields
 * @param {Query} self
 * @param {Array} [pop] array of paths used in population
 * @param {Function} callback
 */

function completeMany(model, docs, fields, userProvidedFields, pop, callback) {
  var arr = [];
  var count = docs.length;
  var len = count;
  var opts = pop ? { populated: pop } : undefined;
  var error = null;
  function init(_error) {
    if (error != null) {
      return;
    }
    if (_error != null) {
      error = _error;
      return callback(error);
    }
    --count || callback(null, arr);
  }
  for (var i = 0; i < len; ++i) {
    arr[i] = helpers.createModel(model, docs[i], fields, userProvidedFields);
    arr[i].init(docs[i], opts, init);
  }
}

/**
 * Adds a collation to this op (MongoDB 3.4 and up)
 *
 * @param {Object} value
 * @return {Query} this
 * @see MongoDB docs https://docs.mongodb.com/manual/reference/method/cursor.collation/#cursor.collation
 * @api public
 */

Query.prototype.collation = function(value) {
  if (this.options == null) {
    this.options = {};
  }
  this.options.collation = value;
  return this;
};

/**
 * Thunk around findOne()
 *
 * @param {Function} [callback]
 * @see findOne http://docs.mongodb.org/manual/reference/method/db.collection.findOne/
 * @api private
 */

Query.prototype._findOne = function(callback) {
  this._castConditions();

  if (this.error()) {
    return callback(this.error());
  }

  this._applyPaths();
  this._fields = this._castFields(this._fields);

  var options = this._mongooseOptions;
  var projection = this._fieldsForExec();
  var userProvidedFields = this._userProvidedFields || {};
  var _this = this;

  // don't pass in the conditions because we already merged them in
  Query.base.findOne.call(_this, {}, function(err, doc) {
    if (err) {
      return callback(err);
    }
    if (!doc) {
      return callback(null, null);
    }

    if (!options.populate) {
      return !!options.lean === true
          ? callback(null, doc)
          : completeOne(_this.model, doc, null, {}, projection, userProvidedFields, null, callback);
    }

    var pop = helpers.preparePopulationOptionsMQ(_this, options);
    pop.__noPromise = true;
    _this.model.populate(doc, pop, function(err, doc) {
      if (err) {
        return callback(err);
      }
      return !!options.lean === true
          ? callback(null, doc)
          : completeOne(_this.model, doc, null, {}, projection, userProvidedFields, pop, callback);
    });
  });
};

/**
 * Declares the query a findOne operation. When executed, the first found document is passed to the callback.
 *
 * Passing a `callback` executes the query. The result of the query is a single document.
 *
 * * *Note:* `conditions` is optional, and if `conditions` is null or undefined,
 * mongoose will send an empty `findOne` command to MongoDB, which will return
 * an arbitrary document. If you're querying by `_id`, use `Model.findById()`
 * instead.
 *
 * This function triggers the following middleware:
 * - `findOne()`
 *
 * ####Example
 *
 *     var query  = Kitten.where({ color: 'white' });
 *     query.findOne(function (err, kitten) {
 *       if (err) return handleError(err);
 *       if (kitten) {
 *         // doc may be null if no document matched
 *       }
 *     });
 *
 * @param {Object} [filter] mongodb selector
 * @param {Object} [projection] optional fields to return
 * @param {Object} [options] see [`setOptions()`](http://mongoosejs.com/docs/api.html#query_Query-setOptions)
 * @param {Function} [callback] optional params are (error, document)
 * @return {Query} this
 * @see findOne http://docs.mongodb.org/manual/reference/method/db.collection.findOne/
 * @see Query.select #query_Query-select
 * @api public
 */

Query.prototype.findOne = function(conditions, projection, options, callback) {
  if (typeof conditions === 'function') {
    callback = conditions;
    conditions = null;
    projection = null;
    options = null;
  } else if (typeof projection === 'function') {
    callback = projection;
    options = null;
    projection = null;
  } else if (typeof options === 'function') {
    callback = options;
    options = null;
  }

  // make sure we don't send in the whole Document to merge()
  conditions = utils.toObject(conditions);

  this.op = 'findOne';

  if (options) {
    this.setOptions(options);
  }

  if (projection) {
    this.select(projection);
  }

  if (mquery.canMerge(conditions)) {
    this.merge(conditions);

    prepareDiscriminatorCriteria(this);

    try {
      this.cast(this.model);
      this.error(null);
    } catch (err) {
      this.error(err);
    }
  } else if (conditions != null) {
    this.error(new ObjectParameterError(conditions, 'filter', 'findOne'));
  }

  if (!callback) {
    // already merged in the conditions, don't need to send them in.
    return Query.base.findOne.call(this);
  }

  this._findOne(callback);

  return this;
};

/**
 * Thunk around count()
 *
 * @param {Function} [callback]
 * @see count http://docs.mongodb.org/manual/reference/method/db.collection.count/
 * @api private
 */

Query.prototype._count = function(callback) {
  try {
    this.cast(this.model);
  } catch (err) {
    this.error(err);
  }

  if (this.error()) {
    return callback(this.error());
  }

  var conds = this._conditions;
  var options = this._optionsForExec();

  this._collection.count(conds, options, utils.tick(callback));
};

/**
 * Specifying this query as a `count` query.
 *
 * Passing a `callback` executes the query.
 *
 * This function triggers the following middleware:
 * - `count()`
 *
 * ####Example:
 *
 *     var countQuery = model.where({ 'color': 'black' }).count();
 *
 *     query.count({ color: 'black' }).count(callback)
 *
 *     query.count({ color: 'black' }, callback)
 *
 *     query.where('color', 'black').count(function (err, count) {
 *       if (err) return handleError(err);
 *       console.log('there are %d kittens', count);
 *     })
 *
 * @param {Object} [criteria] mongodb selector
 * @param {Function} [callback] optional params are (error, count)
 * @return {Query} this
 * @see count http://docs.mongodb.org/manual/reference/method/db.collection.count/
 * @api public
 */

Query.prototype.count = function(conditions, callback) {
  if (typeof conditions === 'function') {
    callback = conditions;
    conditions = undefined;
  }

  if (mquery.canMerge(conditions)) {
    this.merge(conditions);
  }

  this.op = 'count';
  if (!callback) {
    return this;
  }

  this._count(callback);

  return this;
};

/**
 * Declares or executes a distict() operation.
 *
 * Passing a `callback` executes the query.
 *
 * This function does not trigger any middleware.
 *
 * ####Example
 *
 *     distinct(field, conditions, callback)
 *     distinct(field, conditions)
 *     distinct(field, callback)
 *     distinct(field)
 *     distinct(callback)
 *     distinct()
 *
 * @param {String} [field]
 * @param {Object|Query} [criteria]
 * @param {Function} [callback] optional params are (error, arr)
 * @return {Query} this
 * @see distinct http://docs.mongodb.org/manual/reference/method/db.collection.distinct/
 * @api public
 */

Query.prototype.distinct = function(field, conditions, callback) {
  if (!callback) {
    if (typeof conditions === 'function') {
      callback = conditions;
      conditions = undefined;
    } else if (typeof field === 'function') {
      callback = field;
      field = undefined;
      conditions = undefined;
    }
  }

  conditions = utils.toObject(conditions);

  if (mquery.canMerge(conditions)) {
    this.merge(conditions);
  }

  try {
    this.cast(this.model);
  } catch (err) {
    if (!callback) {
      throw err;
    }
    callback(err);
    return this;
  }

  return Query.base.distinct.call(this, {}, field, callback);
};

/**
 * Sets the sort order
 *
 * If an object is passed, values allowed are `asc`, `desc`, `ascending`, `descending`, `1`, and `-1`.
 *
 * If a string is passed, it must be a space delimited list of path names. The
 * sort order of each path is ascending unless the path name is prefixed with `-`
 * which will be treated as descending.
 *
 * ####Example
 *
 *     // sort by "field" ascending and "test" descending
 *     query.sort({ field: 'asc', test: -1 });
 *
 *     // equivalent
 *     query.sort('field -test');
 *
 * ####Note
 *
 * Cannot be used with `distinct()`
 *
 * @param {Object|String} arg
 * @return {Query} this
 * @see cursor.sort http://docs.mongodb.org/manual/reference/method/cursor.sort/
 * @api public
 */

Query.prototype.sort = function(arg) {
  if (arguments.length > 1) {
    throw new Error('sort() only takes 1 Argument');
  }

  return Query.base.sort.call(this, arg);
};

/**
 * Declare and/or execute this query as a remove() operation.
 *
 * This function does not trigger any middleware
 *
 * ####Example
 *
 *     Model.remove({ artist: 'Anne Murray' }, callback)
 *
 * ####Note
 *
 * The operation is only executed when a callback is passed. To force execution without a callback, you must first call `remove()` and then execute it by using the `exec()` method.
 *
 *     // not executed
 *     var query = Model.find().remove({ name: 'Anne Murray' })
 *
 *     // executed
 *     query.remove({ name: 'Anne Murray' }, callback)
 *     query.remove({ name: 'Anne Murray' }).remove(callback)
 *
 *     // executed without a callback
 *     query.exec()
 *
 *     // summary
 *     query.remove(conds, fn); // executes
 *     query.remove(conds)
 *     query.remove(fn) // executes
 *     query.remove()
 *
 * @param {Object|Query} [filter] mongodb selector
 * @param {Function} [callback] optional params are (error, writeOpResult)
 * @return {Query} this
 * @see writeOpResult http://mongodb.github.io/node-mongodb-native/2.2/api/Collection.html#~WriteOpResult
 * @see remove http://docs.mongodb.org/manual/reference/method/db.collection.remove/
 * @api public
 */

Query.prototype.remove = function(filter, callback) {
  if (typeof filter === 'function') {
    callback = filter;
    filter = null;
  }

  filter = utils.toObject(filter, { retainKeyOrder: true });

  try {
    this.cast(this.model, filter);
    this.merge(filter);
  } catch (err) {
    this.error(err);
  }

  prepareDiscriminatorCriteria(this);

  if (!callback) {
    return Query.base.remove.call(this);
  }

  return this._remove(callback);
};

/*!
 * ignore
 */

Query.prototype._remove = function(callback) {
  if (this.error() != null) {
    callback(this.error());
    return this;
  }

  return Query.base.remove.call(this, callback);
};

/**
 * Declare and/or execute this query as a `deleteOne()` operation. Works like
 * remove, except it deletes at most one document regardless of the `single`
 * option.
 *
 * This function does not trigger any middleware.
 *
 * ####Example
 *
 *     Character.deleteOne({ name: 'Eddard Stark' }, ca