"use strict"; /** * @fileOverview The **ReadPreference** class is a class that represents a MongoDB ReadPreference and is * used to construct connections. * * @example * var Db = require('mongodb').Db, * ReplSet = require('mongodb').ReplSet, * Server = require('mongodb').Server, * ReadPreference = require('mongodb').ReadPreference, * test = require('assert'); * // Connect using ReplSet * var server = new Server('localhost', 27017); * var db = new Db('test', new ReplSet([server])); * db.open(function(err, db) { * test.equal(null, err); * // Perform a read * var cursor = db.collection('t').find({}); * cursor.setReadPreference(ReadPreference.PRIMARY); * cursor.toArray(function(err, docs) { * test.equal(null, err); * db.close(); * }); * }); */ /** * Creates a new ReadPreference instance * * Read Preferences * - **ReadPreference.PRIMARY**, Read from primary only. All operations produce an error (throw an exception where applicable) if primary is unavailable. Cannot be combined with tags (This is the default.). * - **ReadPreference.PRIMARY_PREFERRED**, Read from primary if available, otherwise a secondary. * - **ReadPreference.SECONDARY**, Read from secondary if available, otherwise error. * - **ReadPreference.SECONDARY_PREFERRED**, Read from a secondary if available, otherwise read from the primary. * - **ReadPreference.NEAREST**, All modes read from among the nearest candidates, but unlike other modes, NEAREST will include both the primary and all secondaries in the random selection. * * @class * @param {string} mode The ReadPreference mode as listed above. * @param {object} tags An object representing read preference tags. * @property {string} mode The ReadPreference mode. * @property {object} tags The ReadPreference tags. * @return {ReadPreference} a ReadPreference instance. */ var ReadPreference = function(mode, tags) { if(!(this instanceof ReadPreference)) return new ReadPreference(mode, tags); this._type = 'ReadPreference'; this.mode = mode; this.tags = tags; } /** * Validate if a mode is legal * * @method * @param {string} mode The string representing the read preference mode. * @return {boolean} */ ReadPreference.isValid = function(_mode) { return (_mode == ReadPreference.PRIMARY || _mode == ReadPreference.PRIMARY_PREFERRED || _mode == ReadPreference.SECONDARY || _mode == ReadPreference.SECONDARY_PREFERRED || _mode == ReadPreference.NEAREST || _mode == true || _mode == false || _mode == null); } /** * Validate if a mode is legal * * @method * @param {string} mode The string representing the read preference mode. * @return {boolean} */ ReadPreference.prototype.isValid = function(mode) { var _mode = typeof mode == 'string' ? mode : this.mode; return ReadPreference.isValid(_mode); } /** * @ignore */ ReadPreference.prototype.toObject = function() { var object = {mode:this.mode}; if(this.tags != null) { object['tags'] = this.tags; } return object; } /** * @ignore */ ReadPreference.PRIMARY = 'primary'; ReadPreference.PRIMARY_PREFERRED = 'primaryPreferred'; ReadPreference.SECONDARY = 'secondary'; ReadPreference.SECONDARY_PREFERRED = 'secondaryPreferred'; ReadPreference.NEAREST = 'nearest' /** * @ignore */ module.exports = ReadPreference;