Ember.js: How to get an array of model IDs from a corresponding array of model attributes - ember.js

Question

For a Tag model that I have in Ember-Data, I have 4 records in my store:
Tags:
id tag_name
1 Writing
2 Reading-Comprehension
3 Biology
4 Chemistry
In my code I have an array of tag_names, and I want to get a corresponding array of tag IDs. I'm having 2 problems:
My server is being queried even though I have these tags in my store. When I call store.find('tag', {tag_name: tag_name}), I didn't expect to need a call to the server. Here is all the code I'm using to attempt to create an array of IDs.
var self = this;
var tagsArray = ["Writing", "Reading-Comprehension", "Chemistry"];
var tagIdArr = []
tagsArray.forEach(function(tag_name) {
return self.store.find('tag', { tag_name: tag_name }).then(function(tag) {
tagIdArr.pushObject(tag.get('content').get('0').get('id'));
})
})
return tagIdArr;
When I console.log the output of the above code gives me an empty array object with length 0. Clicking on the caret next to the empty array shows three key-value pairs with the correct data. But the array is empty. I'm sure there is a simple explanation for this behavior, but I'm not sure why this is. I've used code similar to the above in other places successfully.

Answer 1

Find hits the server, but peek does not.
var tagsArray = ["Writing", "Reading-Comprehension", "Chemistry"];
return this.store.peekAll('tag').filter(function(tag){
return tagsArray.indexOf(tag) !== -1;
}).mapBy('id');
See: http://emberjs.com/blog/2015/06/18/ember-data-1-13-released.html#toc_reorganized-find-methods