# Count async hasMany without loading **URL:** \ **Category:** Ember Data\ **Created:** [April 8, 2015, 11:16pm UTC](https://discuss.emberjs.com/t/count-async-hasmany-without-loading/7751 "2015-04-08T23:16:08Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![H1D](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.emberjs.com/h1d/32/15291_2.png) [@H1D](https://discuss.emberjs.com/u/H1D)\ **Post date:** [April 8, 2015, 11:16pm UTC](https://discuss.emberjs.com/t/count-async-hasmany-without-loading/7751/1 "2015-04-08T23:16:08Z")
How can I count related objects associated via hasMany without loading all them? Naive `post.get('comments.length')` would first load all comments. I used to do `post.get('data.comments.length')` but now `data` is deprecated =( I know about `post._data` but now I’m afarid to use it (after they added that underscore 😃 ) ---
**Author:** ![H1D](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.emberjs.com/h1d/32/15291_2.png) [@H1D](https://discuss.emberjs.com/u/H1D)\ **Post date:** [April 16, 2015, 3:14pm UTC](https://discuss.emberjs.com/t/count-async-hasmany-without-loading/7751/3 "2015-04-16T15:14:41Z")
Have another problem… How to check if there is associated model (belongsTo)?! ``` {{#if comment.post}} comment.parent will be loaded to display this =( {{/if}} {{#if comment.post.id}} comment.parent still will be loaded to display this =( {{/if}} ``` This also loads `post` model: `hasPost: Ember.computed.notEmpty('post')` The only workaround is to use `_data` =( ---
**Author:** ![H1D](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.emberjs.com/h1d/32/15291_2.png) [@H1D](https://discuss.emberjs.com/u/H1D)\ **Post date:** [April 17, 2015, 11:47am UTC](https://discuss.emberjs.com/t/count-async-hasmany-without-loading/7751/4 "2015-04-17T11:47:21Z")
Here is my dirty workaround. I tweaked serializer: ```coffeescript ApplicationSerializer = DS.RESTSerializer.extend normalize: (type, hash, prop)-> # itarate over properties came from payload for key, value of hash try meta = type.metaForProperty(key) catch e # some keys absent in type class continue injectProperty = (key, value, attr_type)-> if not hash[key] try # absent property will throw Error meta = type.metaForProperty(key) # this type already extended with that property if meta.type is attr_type hash[key] = value catch e hash[key] = value tmp = {} tmp[key] = DS.attr(attr_type) type.reopen tmp switch meta.kind when 'hasMany' # create an array for 'hasMany' injectProperty "#{key}_ids", value.slice(), 'array' injectProperty "has_#{key}", !!value.length, 'boolean' when 'belongsTo' # create and XXX_id and has_XXX for 'belongsTo' injectProperty "#{key}_id", value, 'string' injectProperty "has_#{key}", !!value, 'boolean' return @_super.apply @, arguments ``` This tweaked serialized let’s you check if relationship on a model empty or not without loading associated models, as a bonus you can get ids for associated models. **models** ```coffeescript App.Post = DS.model.extend text: DS.attr 'string' comments: DS.hasMany 'comment', async: true App.Comment = DS.model.extend text: DS.attr 'string' post: DS.belongsTo 'post', async: true ``` **usage** ```handlebars {{#if post.has_comments}} This post has {{post.comments_ids.length}} comments {{/if}} ``` ```handlebars {{#if comment.has_post}} This comment associated with post #{{comment.post_id}} {{/if}} ``` ---
**Author:** ![nandosan](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.emberjs.com/nandosan/32/267_2.png) [@nandosan](https://discuss.emberjs.com/u/nandosan)\ **Post date:** [April 21, 2015, 11:00am UTC](https://discuss.emberjs.com/t/count-async-hasmany-without-loading/7751/5 "2015-04-21T11:00:28Z")
Really interesting solution. So, your backend is always returning all the ids and you’re dealing with them on client side while still having the metadata for the general type available. Have you considered possible decrease in performance when dealing with large set of models? (I know ember-data is not the best solution in this scenario anyway…) I’m going to try it as soon as possible, thanks for sharing! ---
**Author:** ![H1D](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.emberjs.com/h1d/32/15291_2.png) [@H1D](https://discuss.emberjs.com/u/H1D)\ **Post date:** [April 21, 2015, 2:12pm UTC](https://discuss.emberjs.com/t/count-async-hasmany-without-loading/7751/6 "2015-04-21T14:12:49Z")
In cases when ids list may be large (for example comments) we introduce proxy model: ```coffeescript App.Step = DS.Model.extend comment_proxy: DS.belongsTo 'comment-proxy', async: true comments_count: DS.attr 'number' App.CommentProxy = DS.Model.extend comments: DS.hasMany 'comment', async: true App.Comment = DS.Model.extend text: DS.attr 'string' target: DS.belongsTo 'step', async: true ``` So we load `comment_proxy` only when user want to interact with comments. Yes It can be slow. We have item with \>3200 comments check out numbers: - `comment_proxy` payload is about 14kb - it takes about 4 seconds to show comments after user pressed “show comments button” Of course we do not load all 3200 comments, only first 17 comments will be loaded. Anyway we need all ids on client-side to implements permalinks. Here is why: imagine someone linked 3200th comment – you dont want to load ALL comments, so our solution is to extract subarray with linked ID and few siblings load only them and display. BTW discourse have similar solution! Here are 40k+ comments thread – [Login to your account - What the Daily WTF?](http://what.thedailywtf.com/t/the-thread-of/1000/10465) you can open devtools and then try to load this page ---
**Author:** ![remkoboschker](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.emberjs.com/remkoboschker/32/11466_2.png) [@remkoboschker](https://discuss.emberjs.com/u/remkoboschker)\ **Post date:** [March 30, 2016, 7:54am UTC](https://discuss.emberjs.com/t/count-async-hasmany-without-loading/7751/7 "2016-03-30T07:54:19Z")
You can check the new references api [Ember Data 2.4 and 2.5 Beta Released](http://emberjs.com/blog/2016/03/13/ember-data-2-4-released.html#toc_code-ds-references-code)