lib/relations/belongs_to.js
function(instance) {
    var cacheName = this._itemObjectsQueryCacheKey;
    if (!instance[cacheName]) {
      var where = _.object([
        [this.primaryKey, instance.getAttribute(this.foreignKeyAttr)],
      ]);
      var cacheResult = _.bind(this.associateFetchedObjects, this, instance);
      instance[cacheName] = this._relatedModel
        .objects.where(where).limit(1)
        .on('result', cacheResult);
    }
    return instance[cacheName];
  }
function(instance) {
    var cacheName = this._itemObjectsQueryCacheKey;
    if (!instance[cacheName]) {
      var where = _.object([
        [this.primaryKey, instance.getAttribute(this.foreignKeyAttr)],
      ]);
      var cacheResult = _.bind(this.associateFetchedObjects, this, instance);
      instance[cacheName] = this._relatedModel
        .objects.where(where).limit(1)
        .on('result', cacheResult);
    }
    return instance[cacheName];
  }
function ( instance ) { var cacheName = this . _itemObjectsQueryCacheKey ; if ( ! instance [ cacheName ] ) { var where = _ . object ( [ [ this . primaryKey , instance . getAttribute ( this . foreignKeyAttr ) ] , ] ) ; var cacheResult = _ . bind ( this . associateFetchedObjects , this , instance ) ; instance [ cacheName ] = this . _relatedModel . objects . where ( where ) . limit ( 1 ) . on ( 'result' , cacheResult ) ; } return instance [ cacheName ] ; }
The objects query property for this relation.

This property allows you access to a query which you can use to fetch the
object for a relation on a given model and/or to configure the query to
build a new query with more restrictive conditions.

When you fetch the object, the result will be cached and accessible via
the {@link BelongsTo#collection} (if loaded).

The value of this property is a query object that is cached so it will
always be the exact same query object (see exceptions below). This allows
multiple fetches to simply return the query's cached result. A simple
{@link BaseQuery#clone} of the query will ensure that it is always
performing a new query in the database.

The cache of this property will be invalided (and the resulting object a
new query object) when changes are made to the relation.

It is currently not accessible on an individual model.

@method
@protected
@param {Model} instance The model instance on which to operate.
The objects query property for this relation .