On Meteor, get data from a collection while looping on another - node.js

Question

I have a collection that stores a list of posts users follow, and each user have its own document for it. It is structured like this:
{"_id": "12365",
"user": "123548" //user ID
"posts" : [
{"postId": "225"},
{"postId": "688"},
{"postId": "55"},
(...)
]}
user key refers to the _id of that user, created using account package.
I am trying to, while on user profile page, list all posts that user follow, but I am not being able to, by each postId, show that postTitle instead of its Id.
The HTML to render the list is like this:
<p class="title">{{postId}}</p>
And the template helper that get that user's followed posts is like this:
Template.singleUser.helpers({
postsLibrary: function () {
var postsLibraryContent = postsLibrary.find({
user: Meteor.user();
});
},
});
How can I loop in the posts array from the collection of followed posts, but show each of the posts title that refer to each postId? Should I do it inside this helper above?
-- update --
Title is stored on a Collection of posts, like this:
{
"_id": "9845", //same as postId from the other collection
"title": "Lorem Ipsum",
"author": "Peter Parker",
(...)
}

Answer 1

Change your html from this
<p class="title">{{postId}}</p>
To this
{{#each posts}}
<p class="title">{{postId}}</p>
{{/each}}
This will loop over the array posts.

Answer 2

Ok, got it!
Template.singleUser.helpers({
postsLibrary: function () {
var data = [];
//first we find all this current user postLibrary collection
var postsLibraryContent = PostsLibrary.find({
user: this._id
}).posts;
//then for each item on `posts` array:
for (var i = 0; i < postsLibraryContent.length; i++) {
//get that array item postId value and store on a var
var postId = postsLibraryContent[i].postId;
//creates an array with the post data by searching for its _id
postData = Posts.find({
_id: postId
}).fetch();
//and then push those data to an array above created
data.push({
postTitle: postData[0].title,
postAuthor: postData[0].author
})
};
//then return data array
return data;
}
});
And to render it on HTML:
{{#each postsLibrary}}
<li>
<p class="title">{{postTitle}} - {{postAuthor}}</p>
</li>
{{/each}}