Saving backbone model on parse.com - javascript

i can save a model on parse.com writing:
var persona=new Person({username:"filiberto",password:"filiberto"});
persona.save( {
success: function (persona) {
console.log("modello salvato nel db");
console.log(persona.url());
}
});
but if i first fetch a collection,get a specified model and update by save method doesn't work and error is:PUT https://api.parse.com/1/classes/_User/V742NGMTjA 400 (Bad Request)
Models.utenti = new Usercollection();
Models.utenti.fetch({async:false});
var current_user=Models.utenti.get(Parse.User.current().id);
current_user.set_last_activity();
current_user.save();<----PUT https://api.parse.com/1/classes/_User/V742NGMTjA 400 (Bad
Request)
I've tried to update another class on parse.com and works. The class that i can't update is users,maybe a security reason?

I'm unfamiliar with Parse, but according to their API (https://www.parse.com/docs/rest#users), a users request should be a POST not a PUT. Backbone uses PUT to update/sync models, whereas POST is used to create new models. The issue might be that Backbone is assuming that your model has already been saved and using the PUT method to update it.
Parse has a nice tutorial demonstrating the users API with Backbone (https://parse.com/tutorials/todo-app-with-javascript). You might also find this discussion addressing saving vs updating Backbone models helpful (Backbone model.save() is sending PUT instead of POST).
UPDATE: It appears that Parse requires Cross-Origin Resource Sharing (CORS) to modify existing users' data. In practice, this means adding additional information in the request header. See Parse's blog post in the comments below for more info and implementation details.

Related

Ember.js model save sends no data to server

I'm currently building a small demo app using Ember.JS and NodeJS with Express. I've knocked up a simple model and have created an action to save it.
The component has a property called recipe, which is an instance of a model I've defined. The save action is as simple as:
save() {
this.get('recipe').save();
}
Looking at my network tab in Chrome dev tools, I can see the data in the request payload. However, I can't access the data in my Node app. I've logged the full req object and my data isn't there anywhere.
I have a feeling this is to do with the fact that Ember uses the PATCH verb, whereas I'd expect it to use PUT or POST.
Any help is greatly appreciated.
Disclaimer: Without seeing the code it is difficult to give you a definitive answer.
The JSON API specification defines, that updating a resource is done with the PATCH verb. (http://jsonapi.org/format/#crud-updating)
If you chose to use this adapter, you will have to define the appropriate routes in your Express app. Without seeing it, I'd suggest to define the route for PUT and PATCH with the same callback and you'll be fine.
For example:
router.put('/:id', controller.update);
router.patch('/:id', controller.update);
Overriding the HTTP verb in the adapter is not that easy at the moment (Ember Data 2.4). A possible head would be to override the updateRecord method of the adapter. (https://github.com/emberjs/data/blob/v2.4.0/addon/adapters/json-api.js#L115-L133)
Disclaimer: Without seeing the code it is difficult to give you a definitive answer.
You're not receiving the request payload because the 'Content-Type' header has not been set properly.
The JSONAPIAdapter for Ember sends requests with the 'Content-Type' header set to 'application/vnd.api+json'. You'll need to set this in body-parser like so:
app.use(bodyParser.json({ type: 'application/vnd.api+json' }));
In the end, I fixed the issue by using DS.RESTAdapter as opposed to DS.JSONAPIAdapter. The RESTAdapter uses PUT when you save a record while JSONAPIAdapter uses PATCH. I suspect there's some issue in the implementation of PATCH in either Ember or Express.

AngularJS and WebSockets beyond

I just read this post, and I do understand what the difference is. But still in my head I have the question. Can/Should I use it in the same App/Website? Say I want the AngularJs to fetch content and update my page, connecting to a REST api and all of that top stuff. But on top of that I also want a realtime chat, or to trigger events on other clients when there is an update or a message received.
Does Angular support that? Or I need to use something like Socket.io to trigger those events? Does it make sense to use both?
If someone could help me or point me to some good reading about that if there is a purpose for using both of them together.
Hope I'm clear enough. thank you for any help.
Javascript supports WebSocket, so you don't need an additional client side framework to use it. Please take a look at this $connection service declared in this WebSocket based AngularJS application.
Basically you can listen for messages:
$connection.listen(function (msg) { return msg.type == "CreatedTerminalEvent"; },
function (msg) {
addTerminal(msg);
$scope.$$phase || $scope.$apply();
});
Listen once (great for request/response):
$connection.listenOnce(function (data) {
return data.correlationId && data.correlationId == crrId;
}).then(function (data) {
$rootScope.addAlert({ msg: "Console " + data.terminalType + " created", type: "success" });
});
And send messages:
$connection.send({
type: "TerminalInputRequest",
input: cmd,
terminalId: $scope.terminalId,
correlationId: $connection.nextCorrelationId()
});
Usually, since a WebSocket connection is bidirectional and has a good support, you can also use it for getting data from the server in request/response model. You can have the two models:
Publisher/Subscriber: Where the client declares its interest in some topics and set handlers for messages with that topic, and then the server publish (or push) messages whenever it sees fit.
Request/response: Where the client sends a message with a requestID (or correlationId), and listen for a single response for that requestId.
Still, you can have both if you want, and use REST for getting data, and WebSocket for getting updates.
In server side, you may need to use Socket.io or whatever server side framework in order to have a backend with WebSocket support.
As noted in the answer in your linked post, Angular does not currently have built-in support for Websockets. So, you would need to directly use the Websockets API, or use an additional library like Socket.io.
However, to answer your question of if you should use both a REST api and Websockets in a single Angular application, there is no reason you can't have both standard XmlHttpRequest requests for interacting with a REST api, using $http or another data layer library such as BreezeJS, for certain functionality included in various parts of the application and also use Wesockets for another part (e.g. real time chat).
Angular is designed to assist with handling this type of scenario. A typical solution to would be to create one or more controllers to handle the application functionality and update your page and then creating separate Services or Factories that encapsulate the data management of each of your data end points (i.e. the REST api and the realtime chat server), which are then injected into the Controllers.
There is a great deal of information available on using angular services/factories for managing data connections. If you're looking for a resource to help guide you on how to build an Angular application and where data services would fit in, I would recommend checking out John Papa's AngularJS Styleguide, which includes a section on Data Services.
For more information about factories and services, you can check out AngularJS : When to use service instead of factory

Backbone app is trying to POST

I'm fairly new to Backbone so this is probably an obvious mistake...
I've created a customisable form with a few views. I'm pulling in my config data from config.json through my form collection. In the console I'm getting an error:
'POST http://local.ti-url-builder/js/config.json 405 (Method Not Allowed)'
Any ideas? I'm not doing any POST's (that I'm aware of?). I have a feeling its' related to the way I'm pulling the data:
TAG.FormCollection = Backbone.Collection.extend({
model: TAG.FormsModel,
url: "js/config.json",
});
You can view the app here: https://di-campaign.s3.amazonaws.com/redirect/urlbuilder_v2.html
Thanks in advance for any help and useful criticism :)
I visited the link you shared and saw multiple failed POST requests with HTTP status code 412.
Those are getting triggered in form-view.js:
TAG.Section = new TAG.FormSectionCollection();
...
TAG.Section.create( pageAttributes );
The create method of Collection triggers POST request. It saves the model to the server and adds to the collection.
Are you saving a model instance? By default, if you save a model and it doesn't have an id value, a POST request will be sent to the url...

Adding couchdb persistence to a socketio json feed in node

I'm currently researching how to add persistence to a realtime twitter json feed in node.
I've got my stream setup, it's broadcasting to the client, but how do i go about storing this data in a json database such as couchdb, so i can access the stores json when the client first visits the page?
I can't seem to get my head around couchdb.
var array = {
"tweet_id": tweet.id,
"screen_name": tweet.user.screen_name,
"text" : tweet.text,
"profile_image_url" : tweet.user.profile_image_url
};
db.saveDoc('tweet', strencode(array), function(er, ok) {
if (er) throw new Error(JSON.stringify(er));
util.puts('Saved my first doc to the couch!');
});
db.allDocs(function(er, doc) {
if (er) throw new Error(JSON.stringify(er));
//client.send(JSON.stringify(doc));
console.log(JSON.stringify(doc));
util.puts('Fetched my new doc from couch:');
});
These are the two snippets i'm using to try and save / retrieve tweet data. The array is one individual tweet, and needs to be saved to couch each time a new tweet is received.
I don't understand the id part of saveDoc - when i make it unique, db.allDocs only lists ID's and not the content of each doc in the database - and when it's not unique, it fails after the first db entry.
Can someone kindly explain the correct way to save and retrieve this type of json data to couchdb?
I basically want to to load the entire database when the client first views the page. (The database will have less than 100 entries)
Cheers.
You need to insert the documents in the database. You can do this by inserting the JSON that comes from the twitter API or you can insert one status at a time (for loop)
You should create a view that exposes that information. If you saved the JSON directly from Twitter you are going to need to emit several times in your map function
There operations (ingestion and querying) are not the same thing, so you should really do them at the different times in your program.
You should consider running a bg process (maybe in something as simple as a setInterval) that updates your database. Or you can use something like clarinet (http://github.com/dscape/clarinet) to parse the Twitter streaming API directly.
I'm the author of nano, and here is one of the tests that does most of what you need:
https://github.com/dscape/nano/blob/master/tests/view/query.js
For the actual query semantics and for you learn a bit more of how CouchDB works I would suggest you read:
http://guide.couchdb.org/editions/1/en/index.html
I you find it useful I would suggest you buy the book :)
If you want to use a module to interact with CouchDB I would suggest cradle or nano.
You can also use the default http module you find in Node.js to make requests to CouchDB. The down-side is that the default http module tends to be a little verbose. There are alternatives that give you an better API to deal with http requests. The request is really popular.
To get data you need to make a GET request to a view you can find more information here. If you want to create a document you have to use PUT request to your database.

Ways to save Backbone.js model data?

I am more into front end development and have recently started exploring Backbone.js into my app. I want to persist the model data to the server.
Could you please explain me the various way to save the Model data (using json format). I am using Java on server side. Also I have mainly seen REST being used to save data. As i am more into front end dev, i am not aware of REST and other similar stuff.
It would be great if someone could please explain me the process with some simple example.
Basically Models have a property called attributes which are the various values a certain model may have. Backbone uses JSON objects as a simple way to populate these values using various methods that take JSON objects. Example:
Donuts = Backbone.Model.extend({
defaults: {
flavor: 'Boston Cream', // Some string
price: '0.50' // Dollars
}
});
To populate the model there are a few ways to do so. For example, you can set up your model instance by passing in a JSON OR use method called set() which takes a JSON object of attributes.
myDonut = new Donut({'flavor':'lemon', 'price':'0.75'});
mySecondHelping = new Donut();
mySecondHelping.set({'flavor':'plain', 'price':'0.25'});
console.log(myDonut.toJSON());
// {'flavor':'lemon', 'price':'0.75'}
console.log(mySecondHelping.toJSON());
// {'flavor':'plain', 'price':'0.25'}
So this brings us up to saving models and persisting them either to a server. There is a whole slew of details regarding "What is REST/RESTful?" And it is kind of difficult to explain all this in a short blurb here. Specifically with regard to REST and Backbone saving, the thing to wrap your head around is the semantics of HTTP requests and what you are doing with your data.
You're probably used to two kinds of HTTP requests. GET and POST. In a RESTful environment, these verbs have special meaning for specific uses that Backbone assumes. When you want to get a certain resource from the server, (e.g. donut model I saved last time, a blog entry, an computer specification) and that resource exists, you do a GET request. Conversely, when you want to create a new resource you use POST.
Before I got into Backbone, I've never even touched the following two HTTP request methods. PUT and DELETE. These two verbs also have specific meaning to Backbone. When you want to update a resource, (e.g. Change the flavor of lemon donut to limon donut, etc.) you use a PUT request. When you want to delete that model from the server all together, you use a DELETE request.
These basics are very important because with your RESTful app, you probably will have a URI designation that will do the appropriate task based on the kind of request verb you use. For example:
// The URI pattern
http://localhost:8888/donut/:id
// My URI call
http://localhost:8888/donut/17
If I make a GET to that URI, it would get donut model with an ID of 17. The :id depends on how you are saving it server side. This could just be the ID of your donut resource in your database table.
If I make a PUT to that URI with new data, I'd be updating it, saving over it. And if I DELETE to that URI, then it would purge it from my system.
With POST, since you haven't created a resource yet it won't have an established resource ID. Maybe the URI target I want to create resources is simply this:
http://localhost:8888/donut
No ID fragment in the URI. All of these URI designs are up to you and how you think about your resources. But with regard to RESTful design, my understanding is that you want to keep the verbs of your actions to your HTTP request and the resources as nouns which make URIs easy to read and human friendly.
Are you still with me? :-)
So let's get back to thinking about Backbone. Backbone is wonderful because it does a lot of work for you. To save our donut and secondHelping, we simply do this:
myDonut.save();
mySecondHelping.save();
Backbone is smart. If you just created a donut resource, it won't have an ID from the server. It has something called a cID which is what Backbone uses internally but since it doesn't have an official ID it knows that it should create a new resource and it sends a POST request. If you got your model from the server, it will probably have an ID if all was right. In this case, when you save() Backbone assumes you want to update the server and it will send a PUT. To get a specific resource, you'd use the Backbone method .fetch() and it sends a GET request. When you call .destroy() on a model it will send the DELETE.
In the previous examples, I never explicitly told Backbone where the URI is. Let's do that in the next example.
thirdHelping = Backbone.Model.extend({
url: 'donut'
});
thirdHelping.set({id:15}); // Set the id attribute of model to 15
thirdHelping.fetch(); // Backbone assumes this model exists on server as ID 15
Backbone will GET the thirdHelping at http://localhost:8888/donut/15 It will simply add /donut stem to your site root.
If you're STILL with me, good. I think. Unless you're confused. But we'll trudge on anyway. The second part of this is the SERVER side. We've talked about different verbs of HTTP and the semantic meanings behind those verbs. Meanings that you, Backbone, AND your server must share.
Your server needs to understand the difference between a GET, POST, PUT, and DELETE request. As you saw in the examples above, GET, PUT, and DELETE could all point to the same URI http://localhost:8888/donut/07 Unless your server can differentiate between these HTTP requests, it will be very confused as to what to do with that resource.
This is when you start thinking about your RESTful server end code. Some people like Ruby, some people like .net, I like PHP. Particularly I like SLIM PHP micro-framework. SLIM PHP is a micro-framework that has a very elegant and simple tool set for dealing with RESTful activities. You can define routes (URIs) like in the examples above and depending on whether the call is GET, POST, PUT, or DELETE it will execute the right code. There are other solutions similar to SLIM like Recess, Tonic. I believe bigger frameworks like Cake and CodeIgniter also do similar things although I like minimal. Did I say I like Slim? ;-)
This is what excerpt code on the server might look (i.e. specifically regarding the routes.)
$app->get('/donut/:id', function($id) use ($app) {
// get donut model with id of $id from database.
$donut = ...
// Looks something like this maybe:
// $donut = array('id'=>7, 'flavor'=>'chocolate', 'price'=>'1.00')
$response = $app->response();
$response['Content-Type'] = 'application/json';
$response->body(json_encode($donut));
});
Here it's important to note that Backbone expects a JSON object. Always have your server designate the content-type as 'application/json' and encode it in json format if you can. Then when Backbone receives the JSON object it knows how to populate the model that requested it.
With SLIM PHP, the routes operate pretty similarly to the above.
$app->post('/donut', function() use ($app) {
// Code to create new donut
// Returns a full donut resource with ID
});
$app->put('/donut/:id', function($id) use ($app) {
// Code to update donut with id, $id
$response = $app->response();
$response->status(200); // OK!
// But you can send back other status like 400 which can trigger an error callback.
});
$app->delete('/donut/:id', function($id) use ($app) {
// Code to delete donut with id, $id
// Bye bye resource
});
So you've almost made the full round trip! Go get a soda. I like Diet Mountain Dew. Get one for me too.
Once your server processes a request, does something with the database and resource, prepares a response (whether it be a simple http status number or full JSON resource), then the data comes back to Backbone for final processing.
With your save(), fetch(), etc. methods - you can add optional callbacks on success and error. Here is an example of how I set up this particular cake:
Cake = Backbone.Model.extend({
defaults: {
type: 'plain',
nuts: false
},
url: 'cake'
});
myCake = new Cake();
myCake.toJSON() // Shows us that it is a plain cake without nuts
myCake.save({type:'coconut', nuts:true}, {
wait:true,
success:function(model, response) {
console.log('Successfully saved!');
},
error: function(model, error) {
console.log(model.toJSON());
console.log('error.responseText');
}
});
// ASSUME my server is set up to respond with a status(403)
// ASSUME my server responds with string payload saying 'we don't like nuts'
There are a couple different things about this example that. You'll see that for my cake, instead of set() ing the attributes before save, I simply passed in the new attributes to my save call. Backbone is pretty ninja at taking JSON data all over the place and handling it like a champ. So I want to save my cake with coconuts and nuts. (Is that 2 nuts?) Anyway, I passed in two objects to my save. The attributes JSON object AND some options. The first, {wait:true} means don't update my client side model until the server side trip is successful. The success call back will occur when the server successfully returns a response. However, since this example results in an error (a status other than 200 will indicate to Backbone to use the error callback) we get a representation of the model without the changes. It should still be plain and without nuts. We also have access to the error object that the server sent back. We sent back a string but it could be JSON error object with more properties. This is located in the error.responseText attribute. Yeah, 'we don't like nuts.'
Congratulations. You've made your first pretty full round trip from setting up a model, saving it server side, and back. I hope that this answer epic gives you an IDEA of how this all comes together. There are of course, lots of details that I'm cruising past but the basic ideas of Backbone save, RESTful verbs, Server-side actions, Response are here. Keep going through the Backbone documentation (which is super easy to read compared to other docs) but just keep in mind that this takes time to wrap your head around. The more you keep at it the more fluent you'll be. I learn something new with Backbone every day and it gets really fun as you start making leaps and see your fluency in this framework growing. :-)
EDIT: Resources that may be useful:
Other Similar Answers on SO:
How to generate model IDs with Backbone
On REST:
http://rest.elkstein.org/
http://www.infoq.com/articles/rest-introduction
http://www.recessframework.org/page/towards-restful-php-5-basic-tips

Categories