javascript - Ember find existing hasMany models -

how can (or rather check existence of) sub-model objects belong parent model in ember-data (v1.13.15) without throwing errors?

i have associated models looking this:

// models/parent.js ... export default ds.model.extend({     children: ds.hasmany('child', {async:true, inverse:'parent'}), ... });   // models/child.js ... export default ds.model.extend({     parent: ds.belongsto('parent', {async:true, inverse:'children'}), .... }); 

in route's model hook i'm trying check if have children associated parent (parent btw submodel of hasmany/belongsto of 'family' model...). if haven't added children yet, need create , associate them parent object, when like:

parent.get('children').then(function(children){     // nice in here , maybe have children.length == 0 }); 

i uncaught (in promise) typeerror: cannot read property 'then' of undefined. can't call parent.get('children').get('length'). this.store.findall('child').then... seems error out.

is not possible empty array or have use dirty catch figure out if have submodels? i'm pretty inexperienced ember pointers or appreciated. thanks!