Accessing meta information passed in a json server response - ember.js

Question

I am using the Ember-Data Rest-Adapter and the JSON returned from my server looks basically like the one in the Active Model Serializers Documentation
{
"meta": { "total": 10 },
"posts": [
{ "title": "Post 1", "body": "Hello!" },
{ "title": "Post 2", "body": "Goodbye!" }
]
}
Fetching the data from the server works but unfortunately I am not able to figure out where I can access the meta information from my JSON response.
Based on my research in ember-data's github issue, support for meta information seems to be implemented with commit 1787bff.
But even with the test cases I was not able to figure out how to access the meta information.
App.PostController = Ember.ArrayController.extend({
....
requestSearchData: function(searchParams){
posts = App.Post.find(searchParams);
this.set('content', posts);
// don't know how to access meta["total"]
// but I want to do something like this:
// this.set('totalCount', meta["total"])
}
})
Can anybody of you shed some light on this for me, please? I am aware that the Ember api is moving fast but I am sure I am just missing a small part and that this is actually possible.

Answer 1

I found a cleaner approach for extracting meta information from the server response with ember-data.
We have to tell the serializer which meta-information to expect (in this case pagination):
App.serializer = DS.RESTSerializer.create();
App.serializer.configure({ pagination: 'pagination' });
App.CustomAdapter = DS.RESTAdapter.extend({
serializer: App.serializer
});
App.Store = DS.Store.extend({
adapter: 'App.CustomAdapter'
});
After that every time the server sends a meta-property with a pagination object this object will be added to the store's TypeMaps property for the requested Model-Class.
For example with the following response:
{
'meta': {'pagination': { 'page': 1, 'total': 10 } },
'posts':[
...
]
}
The TypeMap for the App.Post-Model would include the pagination object after the posts have loaded.
You can't observe the TypeMaps-property of the store directly so I added an computed property to the PostsController to have access to the requests pagination meta information:
App.PostsController = Ember.ArrayController.extend({
pagination: function () {
if (this.get('model.isLoaded')) {
modelType = this.get('model.type');
this.get('store').typeMapFor(modelType).metadata.pagination
}
}.property('model.isLoaded')
});
I really don't think that's a great solution to the meta information problem but this is the best solution I was able to come up with yet with Ember-Data. Maybe this will be easier in the future.

Answer 2

I figured out a way to access the meta information passed in a response. But unfortunately it really does not seem to be supported by ember-data out of the box and I am writing the meta information to a global variable that I am then accessing via bindings in the requesting controller.
I ended up customizing the serializer the RESTAdapter is using:
App.CustomRESTSerializer = DS.RESTSerializer.extend({
extractMeta: function(loader, type, json) {
var meta;
meta = json[this.configOption(type, 'meta')];
if (!meta) { return; }
Ember.set('App.metaDataForLastRequest', meta);
this._super(loader, type, json);
}
});
App.Store = DS.Store.extend({
revision: 11,
adapter: DS.RESTAdapter.create({
bulkCommit: false,
serializer: App.CustomRESTSerializer
})
});
I am aware that this is not particularly pretty and actually think that this is against what ember-data expects us to do but fot the time being it's working correctly.
I will try to get this working with ember-data in a better way and submit a pull request when it is working or open an issue on github when anybody else is interested in getting this to work.
If anybody finds a more clean solution to this please let me know.

Answer 3

I think the immediate fix for you would be to attach totalCount to your model(recordArray), see this thread.
Another way to go would be to create your own adapter:
DS.Adapter.create({
find: function (store, type, id) {
$.ajax({
url: type.url,
dataType: 'jsonp',
context: store,
success: function(response){
this.load(type, id, response.data);
}
});
},
findAll: function(store, type) {
$.ajax({
url: type.url,
dataType: 'jsonp',
context: store,
success: function(response){
this.loadMany(type, response.data);
}
});
}
});
Response parameter in success callback in findAll method, should be an object that you need:
response: {
meta: {
totalCount: 10
},
posts: [{}, {}]
}
Hope this helps.