leancloud-storage/dist/node/relation.js

LeanCloud JavaScript SDK.

"use strict";

var _ = require('underscore');

module.exports = function (AV) {
  /**
   * Creates a new Relation for the given parent object and key. This
   * constructor should rarely be used directly, but rather created by
   * {@link AV.Object#relation}.
   * @param {AV.Object} parent The parent of this relation.
   * @param {String} key The key for this relation on the parent.
   * @see AV.Object#relation
   * @class
   *
   * <p>
   * A class that is used to access all of the children of a many-to-many
   * relationship.  Each instance of AV.Relation is associated with a
   * particular parent object and key.
   * </p>
   */
  AV.Relation = function (parent, key) {
    if (!_.isString(key)) {
      throw new TypeError('key must be a string');
    }

    this.parent = parent;
    this.key = key;
    this.targetClassName = null;
  };
  /**
   * Creates a query that can be used to query the parent objects in this relation.
   * @param {String} parentClass The parent class or name.
   * @param {String} relationKey The relation field key in parent.
   * @param {AV.Object} child The child object.
   * @return {AV.Query}
   */


  AV.Relation.reverseQuery = function (parentClass, relationKey, child) {
    var query = new AV.Query(parentClass);
    query.equalTo(relationKey, child._toPointer());
    return query;
  };

  _.extend(AV.Relation.prototype,
  /** @lends AV.Relation.prototype */
  {
    /**
     * Makes sure that this relation has the right parent and key.
     * @private
     */
    _ensureParentAndKey: function _ensureParentAndKey(parent, key) {
      this.parent = this.parent || parent;
      this.key = this.key || key;

      if (this.parent !== parent) {
        throw new Error('Internal Error. Relation retrieved from two different Objects.');
      }

      if (this.key !== key) {
        throw new Error('Internal Error. Relation retrieved from two different keys.');
      }
    },

    /**
     * Adds a AV.Object or an array of AV.Objects to the relation.
     * @param {AV.Object|AV.Object[]} objects The item or items to add.
     */
    add: function add(objects) {
      if (!_.isArray(objects)) {
        objects = [objects];
      }

      var change = new AV.Op.Relation(objects, []);
      this.parent.set(this.key, change);
      this.targetClassName = change._targetClassName;
    },

    /**
     * Removes a AV.Object or an array of AV.Objects from this relation.
     * @param {AV.Object|AV.Object[]} objects The item or items to remove.
     */
    remove: function remove(objects) {
      if (!_.isArray(objects)) {
        objects = [objects];
      }

      var change = new AV.Op.Relation([], objects);
      this.parent.set(this.key, change);
      this.targetClassName = change._targetClassName;
    },

    /**
     * Returns a JSON version of the object suitable for saving to disk.
     * @return {Object}
     */
    toJSON: function toJSON() {
      return {
        __type: 'Relation',
        className: this.targetClassName
      };
    },

    /**
     * Returns a AV.Query that is limited to objects in this
     * relation.
     * @return {AV.Query}
     */
    query: function query() {
      var targetClass;
      var query;

      if (!this.targetClassName) {
        targetClass = AV.Object._getSubclass(this.parent.className);
        query = new AV.Query(targetClass);
        query._defaultParams.redirectClassNameForKey = this.key;
      } else {
        targetClass = AV.Object._getSubclass(this.targetClassName);
        query = new AV.Query(targetClass);
      }

      query._addCondition('$relatedTo', 'object', this.parent._toPointer());

      query._addCondition('$relatedTo', 'key', this.key);

      return query;
    }
  });
};