Develop Reference

Parse React - Observe Objects created by Parse.User.current()

I'm using the excellent parse-react library to get Parse and ReactJS to work together nicely (n.b I've only been playing around for a few hours so apologies if I've misunderstood any of the basics of reactjs).
All was going well until I wanted to query a table for all objects created by the current user (Parse.user.current())
The observe method works correctly on load and the view is rendered with the correct objects (the objects created by the current user). However if I mutate the data and add a new object then the view doesn't re-render.
Abstracted code:
module.exports = React.createClass({
mixins: [ParseReact.Mixin],
getInitialState: function() {
return {
selected: null
};
},
observe: function() {
return {
places: (new Parse.Query('Place'))
.equalTo('user', Parse.User.current())
.descending('createdAt')
};
},
clickHandler: function(event) {
var id = event.target.id;
if (id === 'new') {
ParseReact.Mutation.Create('Place', {
name: 'New Place',
user: Parse.User.current()
}).dispatch();
} else if(id.indexOf('Place:') === 0) {
this.setState({
selected: id.substring(6)
});
}
},
render: function() {
var that = this;
var navItems = this.data.places.map(function(place) {
return (
<UserNavItem id={place.id} key={place.id} label={place.name} selected={that.state.selected === place.objectId} onClick={that.clickHandler}/>
);
});
return (
<ul>
{navItems}
<UserNavItem id='new' label='+ New Place' onClick={this.clickHandler} />
</ul>
);
}
});
If I remove the part of the query that specifies the user:
.equalTo('user', Parse.User.current())
Then it works; new place objects appear in the list when added.
Has anyone got any idea what I'm doing wrong?
Am I using Parse queries incorrectly? It always seems strange that getting the data pertaining to the current user is a bit of a pain when this seems like such a common use case?
Thanks!

The solution is to call the .refreshQueries() method of the component when the new object is successfully created in Parse as described here.
My updated example:
ParseReact.Mutation.Create('Place', {
name: 'New Place',
user: Parse.User.current()
})
.dispatch()
.then(function() {
this.refreshQueries();
}.bind(this));
Thanks very much to Joshua Sierles over on the ParseReact github repo for pointing me to the solution. If you are on SO Joshua I'll give you the credit if you post your answer here :D

Load data belonging to a parent model with Ember.js

Considering something similar to the example outlined here:
App.Router.map(function() {
this.resource("posts", function() {
this.resource("post", { path: "/posts/:post_id" }, function() {
this.resource("comments", { path: "/comments" });
});
});
});
using the DS.RESTAdapter. The Router would load all the posts when I access the PostsRoute with a call to the API URL /posts.
When I then access PostRoute, for example for the post with id=1, it doesn't hit the API again, i.e. it doesn't hit /post/1. It loads the post from the store.
I want then to access CommentsRoute for post with id=1. How do I load the comments?
Should I have sideloaded all the comments in the first place, when I loaded the post list? In this case though, I would need to load all the comments for all the posts. Is it possible to load the comments only when needed, i.e. when I access CommentsRoute?
In this case, how do I actually load the comments from the backend?
Specifically, how do I write the CommentsRoute to load the comments from the RESTful API when I access the page that actually displays them?
I guess one needs to have the following:
App.Post = DS.Model.extend({
comments: DS.hasMany('comment')
});
App.Comment = DS.Model.extend({
post: DS.belongsTo('post')
});
App.CommentsRoute = Ember.Route.extend({
model: function() {
/*
* How do I inject params.post_id here
* to make a request to the RESTful API?
* Which URL would be called?
* /comments?post_id=ID
* /post/post_id/comments
* ...
*/
// Doesn't work, hits /comments
return this.store.find('comment', { post_id: params.post_id });
}
});
Why does
return this.store.find('comment', { post_id: params.post_id });
hit /comments?

You just need to declare your CommentsRoute like this:
App.CommentsRoute = Ember.Route.extend({
model: function() {
return this.modelFor('post').get('comments');
}
});
What it does is, it gets the model of the PostRoute and fetches its comments.
Ember-data handles the logic behind it. If comments were sideloaded, it will just return these. Otherwise it will issue a GET request to fetch them.
For this to work, you need to include the links property on a serialized post. The links property needs to include the URL you wish ember-data to use in order to fetch the comments.
E.g. your serialized post may look like this:
{
"post": {
"id": 1,
"title": "Rails is omakase",
"links": { "comments": "/posts/1/comments" }
}
}
See DS.RESTAdapter#findHasMany.
The hasMany relationship probably needs to be declared async for this to work properly:
App.Post = DS.Model.extend({
comments: DS.hasMany('comment', { async: true })
});

You can use Ember's sideloaded relationships to make the posts API endpoint also return the relevant comments and Ember will figure it out.
http://emberjs.com/guides/models/the-rest-adapter/#toc_sideloaded-relationships
{
"post": {
"id": 1,
"title": "Node is not omakase",
"comments": [1, 2, 3]
},
"comments": [{
"id": 1,
"body": "But is it _lightweight_ omakase?"
},
{
"id": 2,
"body": "I for one welcome our new omakase overlords"
},
{
"id": 3,
"body": "Put me on the fast track to a delicious dinner"
}]
}
You'd then be able to pass the already loaded comments to the comments route.
It may be in the docs but it's quite a specific term! Some of the concepts like that can be a bit tricky to search for.

The following forces a call to the backend /comments?post_id=ID
App.CommentsController = Ember.ArrayController.extend({
needs: 'post'
});
App.CommentsRoute = Ember.Route.extend({
model: function(params) {
return this.store.find('comment', { post_id: this.modelFor('post').get('id') });
}
});

How to add a new object to an array nested inside an object?

I'm trying to get a handle on using $resource in angularjs and I keep referencing this answer AngularJS $resource RESTful example for good examples. Fetching a record and creating a record work fine, but now i'm trying to add a "section" to an existing mongo record but can't figure it out.
documents collection
{
_id: 'theid',
name: 'My name",
sections: [
{
title: 'First title'
},
{
title: 'Second title'
}
]
}
angular controller snippet
var document = documentService.get({_id: 'theid'});
// TRYING TO ADD $scope.section TO THE SECTIONS ARRAY IN THE VARIABLE document.
//document.sections.push($scope.section); <-- This does NOT work
//document.new_section($scope.section); <-- could do this and then parse it out and insert it in my backend code, but this solution seems hacky and terrible to me.
document.$save(function(section) {
//$scope.document.push(section);
});
documentService
return $resource(SETTINGS.base + '/documents/:id', { id: '#id' },
{
update: { method: 'PUT' }
});
From the link i posted above, If I was just updating the name field, I could just do something like this:
var document = documentService.get({_id: 'theid'});
document.name = "My new name";
document.$save(function(section) {
//$scope.document.push(section);
});
I'm just trying to add an object to a nested array of objects.

Try this:
documentService.get({_id: 'theid'}, function(document) {
document.sections.push($scope.section);
document.$save();
});

Mapping JSON to backbone.js collections

Alright, it looks like I need a hint to point me in the right direction. This question is two part - working with mult-dimensional JSON and Collections of Collections from JSON.
Background
I have some JSON that is going to be retrieved from a server and have control over how it could be formatted.
Multi-Dimentional JSON
I'm having some trouble being able connecting the model to the parts in the JSON. Say I wanted to render just each of the posts author name, and the content of status in the sample JSON below. I'm having no problem getting the status into the model, but the author name I'm a bit confused how to get to it. From my understanding I have to override the parse.
Is this bad standards / is there a better JSON structure I should use? Would it be better to keep it as flat as possible? That is move the author name and photo up one level?
I was reading How to build a Collection/Model from nested JSON with Backbone.js but it is still a little unclear to me.
Collection in Collections
Is there a nice way to make a collection within a collection for backbone.js? I will have a collection of posts, and then would have a collection of comments on that post. As I'm developing in backbone is that even possible?
From what I understand in Backbone.js Collection of Collections and Backbone.js Collection of Collections Issue, it would look something like this?
var Comments = Backbone.Model.extend({
defaults : {
_id : "",
text : "",
author : ""
}
})
var CommentsCollection = Backbone.Collection.extend({ model : Comments })
var Posts = Backbone.Model.extend({
defaults : {
_id : "",
author : "",
status : "",
comments : new CommentsCollection
}
})
var PostsCollection = Backbone.Collection.extend({ model : Posts })
Sample JSON
{
"posts" : [
{
"_id": "50f5f5d4014e045f000002",
"author": {
"name" : "Chris Crawford",
"photo" : "http://example.com/photo.jpg"
},
"status": "This is a sample message.",
"comments": [
{
"_id": "5160eacbe4b020ec56a46844",
"text": "This is the content of the comment.",
"author": "Bob Hope"
},
{
"_id": "5160eacbe4b020ec56a46845",
"text": "This is the content of the comment.",
"author": "Bob Hope"
},
{
...
}
]
},
{
"_id": "50f5f5d4014e045f000003",
"author": {
"name" : "Chris Crawford",
"photo" : "http://example.com/photo.jpg"
},
"status": "This is another sample message.",
"comments": [
{
"_id": "5160eacbe4b020ec56a46846",
"text": "This is the content of the comment.",
"author": "Bob Hope"
},
{
"_id": "5160eacbe4b020ec56a46847",
"text": "This is the content of the comment.",
"author": "Bob Hope"
},
{
...
}
]
},
{
...
}
]}
I appreciate even any hints to guild me. Thanks!

It can be overwhelming when trying to write up code to make it work for nested objects. But to make it simpler lets break it up into smaller manageable pieces.
I would think in these lines.
Collections
Posts
Comments
Models
Post
Comment
Author
Main collection -- Posts collection
(Which contains list of Post Models)
And each model in the Posts collection will have 3 sets of attributes(May not be the right term).
1st - level of attributes (status , id).
2nd - Author attribute which can be placed in a separate Model(Authod Model).
3rd - Collection of comments for each Post Model.
Collection in Collections would be a bit confusing here.
As you would have Models in Collection(Post Model inside Posts Collection) and each Model will nest a collection again(Comments collection inside Post Model). Basically you would be Handling a Collection inside a Model.
From my understanding I have to override the parse.
Is this bad standards / is there a better JSON structure I should use?
It is a perfectly plausible solution to handle the processing this in the Parse method. When you initialize a Collection or a Model , Parse methods is first called and then initialize is called. So it is perfectly logical to handle the logic inside the Parse method and it is not at all a bad standard.
Would it be better to keep it as flat as possible?
I don't think it is a good idea to keep this flat at a single level, as the other data is not required on the first level in the first place.
So the way I would approach this problem is write up the parse method in the Post Model which processes the response and attach the Author model and Comments collection directly on the Model instead as an attribute on the Model to keep the attributes hash clean consisting of 1st level of Post data. This I feel will be cleaner and lot more scalable on the long run.
var postsObject = [{
"_id": "50f5f5d4014e045f000002",
"author": {
"name": "Chris Crawford",
"photo": "http://example.com/photo.jpg"
},
"status": "This is a sample message.",
"comments": [{
"_id": "5160eacbe4b020ec56a46844",
"text": "This is the content of the comment.",
"author": "Bob Hope"
}, {
"_id": "5160eacbe4b020ec56a46845",
"text": "This is the content of the comment.",
"author": "Bob Hope"
}]
}, {
"_id": "50f5f5d4014e045f000003",
"author": {
"name": "Brown Robert",
"photo": "http://example.com/photo.jpg"
},
"status": "This is another sample message.",
"comments": [{
"_id": "5160eacbe4b020ec56a46846",
"text": "This is the content of the comment.",
"author": "Bob Hope"
}, {
"_id": "5160eacbe4b020ec56a46847",
"text": "This is the content of the comment.",
"author": "Bob Hope"
}]
}];
// Comment Model
var Comment = Backbone.Model.extend({
idAttribute: '_id',
defaults: {
text: "",
author: ""
}
});
// Comments collection
var Comments = Backbone.Collection.extend({
model: Comment
});
// Author Model
var Author = Backbone.Model.extend({
defaults: {
text: "",
author: ""
}
});
// Post Model
var Post = Backbone.Model.extend({
idAttribute: '_id',
defaults: {
author: "",
status: ""
},
parse: function (resp) {
// Create a Author model on the Post Model
this.author = new Author(resp.author || null, {
parse: true
});
// Delete from the response object as the data is
// alredy available on the model
delete resp.author;
// Create a comments objecton model
// that will hold the comments collection
this.comments = new Comments(resp.comments || null, {
parse: true
});
// Delete from the response object as the data is
// alredy available on the model
delete resp.comments;
// return the response object
return resp;
}
})
// Posts Collection
var Posts = Backbone.Collection.extend({
model: Post
});
var PostsListView = Backbone.View.extend({
el: "#container",
renderPostView: function(post) {
// Create a new postView
var postView = new PostView({
model : post
});
// Append it to the container
this.$el.append(postView.el);
postView.render();
},
render: function () {
var thisView = this;
// Iterate over each post Model
_.each(this.collection.models, function (post) {
// Call the renderPostView method
thisView.renderPostView(post);
});
}
});
var PostView = Backbone.View.extend({
className: "post",
template: _.template($("#post-template").html()),
renderComments: function() {
var commentsListView = new CommentsListView({
// Comments collection on the Post Model
collection : this.model.comments,
// Pass the container to which it is to be appended
el : $('.comments', this.$el)
});
commentsListView.render();
},
render: function () {
this.$el.empty();
// Extend the object toi contain both Post attributes
// and also the author attributes
this.$el.append(this.template(_.extend(this.model.toJSON(),
this.model.author.toJSON()
)));
// Render the comments for each Post
this.renderComments();
}
});
var CommentsListView = Backbone.View.extend({
renderCommentView: function(comment) {
// Create a new CommentView
var commentView = new CommentView({
model : comment
});
// Append it to the comments ul that is part
// of the view
this.$el.append(commentView.el);
commentView.render();
},
render: function () {
var thisView = this;
// Iterate over each Comment Model
_.each(this.collection.models, function (comment) {
// Call the renderCommentView method
thisView.renderCommentView(comment);
});
}
});
var CommentView = Backbone.View.extend({
tagName: "li",
className: "comment",
template: _.template($("#comment-template").html()),
render: function () {
this.$el.empty();
this.$el.append(this.template(this.model.toJSON()));
}
});
// Create a posts collection
var posts = new Posts(postsObject, {parse: true});
// Pass it to the PostsListView
var postsListView = new PostsListView({
collection: posts
});
// Render the view
postsListView.render();
Check Fiddle

(Edited to correct my initial misreading of the question.)
There's no need to override parse method of the model unless you want to change its structure. But it sounds like you don't need to -- to render the author name, just use author.name in the view:
<%= author.name %>
As far as initializing the nested collection, your approach is exactly right. All you have to do is convert the JSON object to Backbone models, and pass them to the PostsCollection (the Backbone.Collection constructor accepts an array of Backbone models, not raw JSON). One way of doing this is to use map:
var postModels = json.posts.map(function(post) { return new Posts(post); });
var posts = new PostsCollection(postModels);
Note that you'll need to do something similar in the initialize method of the Posts model -- retrieve the comments JSON array, and convert it to an array of Comments models:
initialize: function() {
if (attributes.comments && attributes.comments.length > 0) {
var commentModels = attributes.comments.map(function(comment) {
return new Comments(comment);
});
this.set("comments", new CommentsCollection(commentModels));
}
}
Here is working example.

Update, I found a SuperModel for backbone which provides relationships between models and between collections. It has proved to be a great solution for Collections within Collections as well as Deep Nested Model data.
Models are pre-defined with their relationships to other models via key. During the initialize/parse of the model any values in the JSON at that key gets passed off to a new related model or collection. A relationship is created between the two models/collections.
This means with the above example we can do something like this with our models:
Setup
var Author = Supermodel.Model.extend({});
var Post = Supermodel.Model.extend({});
var Comment = Supermodel.Model.extend({});
var Posts = Backbone.Collection.extend({
model: function(attrs, options) {
return Post.create(attrs, options);
}
});
var Comments = Backbone.Collection.extend({
model: function(attrs, options) {
return Comment.create(attrs, options);
}
});
Post.has().one('author', {
model: Author,
inverse: 'post'
}).many('comments', {
collection: Comments,
inverse: 'post'
});
//reverse relationships could also be setup
Usage
var posts = new Posts( postsObject ); //where postsObject is an array of posts
//With SuperModel, we are able to navigate the related models
posts.first().comments();
posts.first().comments().author();
posts.last().author();
Fiddle
Working Example in JSFiddle

Looking for design pattern to create multiple models/collections out of single JSON responses

I have a Backbone application where the JSON I get from the server isn't exactly 1 on 1 with how I want my models to look. I use custom parse functions for my models, ex:
parse: function(response) {
var content = {};
content.id = response.mediaId;
content.image = response.image.url;
return content;
}
This works. But, in some cases I have an API call where I get lots of information at once, for instance, information about an image with its user and comments:
{
"mediaId": "1",
"image": {
"title": "myImage",
"url": "http://image.com/234.jpg"
},
"user": {
"username": "John"
},
"comments": [
{
"title": "Nice pic!"
},
{
"title": "Great stuff."
}
]
}
How would I go about creating a new User model and a Comments collection from here? This is an option:
parse: function(response) {
var content = {};
content.id = response.mediaId;
content.image = response.image.url;
content.user = new User(response.user);
content.comments = new Comments(response.comments);
return content;
}
The trouble here is, by creating a new User or new Comments with raw JSON as input, Backbone will just add the JSON properties as attributes. Instead, I'd like to have an intermediate parse-like method to gain control over the objects' structure. The following is an option:
parse: function(response) {
// ...
content.user = new User({
username: response.user.username
});
// ...
}
...but that's not very DRY-proof.
So, my question is: what would be a nice pattern to create several models/collections out of 1 JSON response, with control over the models/collections attributes?
Thanks!

It may not be the nicest way possible, but this is how I do it:
content.user = new User(User.prototype.parse(response.user));
The only problem is that the this context in User.parse will be wrong. If you don't have any specific code in the User constructor, you can also do:
content.user = new User();
content.user.set(user.parse(response.user));
I also noticed an interesting note in the Backbone version 0.9.9 change log:
The parse function is now always run if defined, for both collections and models — not only after an Ajax call.
And looking at the source code of Model and Collection constructor, they do it like so:
if (options && options.parse) attrs = this.parse(attrs);
Maybe upgrading to 0.9.9 will give you what you need? If upgrade is not an option, you can of course implement the same in your own constructor.