I've been using StackMob's fetch() function to retrieve all objects in my table, given by the fetch() method as a single model object. Each object has multiple attributes with corresponding values. I've then used JSON.stringify(model) to get this output:
{"0":{"attribute1":val1,"attribute2":"val2","attribute3":val3,"attribute4":"val4"},
"1":{"attribute1":val1,"attribute2":"val2","attribute3":val3,"attribute4":"val4"},
"2":{"attribute1":val1,"attribute2":"val2","attribute3":val3,"attribute4":"val4"}
...and so on.
How can I print out just each of those values?
StackMob has a get() function that can be used as such:
var a_book = new Book({ 'title': 'The Complete Calvin and Hobbes', 'author': 'Bill Watterson' });
console.debug(a_book.get('title')); //prints out "The Complete Calvin and Hobbes"
But I'm not sure how I would use it in my situation, where I'm retrieving all of the objects in my table, rather than creating a new object (as above).
since the stackmob js sdk is built on backbonejs you could declare a collection which can contain all the "rows" in your "table" and then iterate through the collection to perform whatever action you want to each item in your "table"
var MyModel = StackMob.Model.extend({
schemaName:'YOUR_SCHEMA_NAME'
});
var MyCollection= StackMob.Collection.extend({
model:MyModel
});
var myCollection = new MyCollection();
myCollection.fetch({async: true});
myCollection.each(function(item){
//do something with item, maybe print
});
Related
I have a collection which is fetched from a REST endpoint, where it receives a JSON.
So to be completely clear:
var Products = Backbone.Collection.extend({
model: Product,
url : 'restendpoint',
customFilter: function(f){
var results = this.where(f);
return new TestCollection(results);
}
});
var products = new Products();
products.fetch();
If I log this, then I have the data. However, the length of the object (initial) is 0, but it has 6 models. I think this difference has something to do with what is wrong, without me knowing what is actually wrong.
Now, if I try to filter this:
products.customFilter({title: "MyTitle"});
That returns 0, even though I know there is one of that specific title.
Now the funky part. If I take the ENTIRE JSON and copy it, as in literally copy/paste it into the code like this:
var TestCollection = Backbone.Collection.extend({
customFilter: function(f){
var results = this.where(f);
return new TestCollection(results);
}
});
var testCollectionInstance = new TestCollection(COPY PASTED HUGE JSON DATA);
testCollectionInstance.customFilter({title: "MyTitle"});
Now that returns the 1 model which I was expecting. The difference when I log the two collections can be seen below. Is there some funky behaviour in the .fetch() I am unaware of?
Edit 2: It may also be of value that using the .fetch() I have no problems actually using the models in a view. It's only the filtering part which is funky.
Edit 3: Added the view. It may very well be that I just don't get the flow yet. Basically I had it all working when I only had to fetch() the data and send it to the view, however, the fetch was hardcoded into the render function, so this.fetch({success: send to template}); This may be wrong.
What I want to do is be able to filter the collection and send ANY collection to the render method and then render the template with that collection.
var ProductList = Backbone.View.extend({
el: '#page',
render: function(){
var that = this; /* save the reference to this for use in anonymous functions */
var template = _.template($('#product-list-template').html());
that.$el.html(template({ products: products.models }));
//before the fetch() call was here and then I rendered the template, however, I needed to get it out so I can update my collection and re-render with a new one (so it's not hard-coded to fetch so to speak)
},
events: {
'keyup #search' : 'search'
},
search : function (ev){
var letters = $("#search").val();
}
});
Edit: New image added to clearify the problem
It's a bit tricky, you need to understand how the console works.
Logging objects or arrays is not like logging primitive values like strings or numbers.
When you log an object to the console, you are logging the reference to that object in memory.
In the first log that object has no models but once the models are fetched the object gets updated (not what you have previously logged!) and now that same object has 6 models. It's the same object but the console prints the current value/properties.
To answer your question, IO is asynchronous. You need to wait for that objects to be fetched from the server. That's what events are for. fetch triggers a sync event. Model emits the sync when the fetch is completed.
So:
var Products = Backbone.Collection.extend({
model: Product,
url : 'restendpoint',
customFilter: function(f){
var results = this.where(f);
return new TestCollection(results);
}
});
var products = new Products();
products.fetch();
console.log(products.length); // 0
products.on('sync',function(){
console.log(products.length); // 6 or whatever
products.customFilter({title: 'MyTitle'});
})
It seems like a response to your ajax request hasn't been received yet by the time you run customFilter. You should be able to use the following to ensure that the request has finished.
var that = this;
this.fetch({
success: function () {
newCollection = that.customFilter({ title: 'foo' });
}
});
I am using a collection to fetch data from an API to place this into a model.
I do receive all data from the API, however the data is returned in an object and I only need a part of this object.
Let me clarify this with an example of the returned JSON:
{
"all-users":
[
{"username":"poekoe","lastsyncdate":"1376496898"},
{"username":"plaap","lastsyncdate":"1376494547"}
],
"total-users": "10",
"selected": 2
}
This is the JSON returned, however I only want need the 'all-users' array to be placed in my model.
At this point I am fetching data like this:
var userCollection = new UserCollection;
userCollection.fetch({
data: {
"search": "p",
"session: login.session
}
});
What can I do here to only use the 'all-users' array to be placed in the model?
Is there something in the Fetch what I can do? or should I alter the Model to only use the all-users array?
Thanks in advance!
You can override the parse method of the collection:
var UserCollection = new Backbone.Collection.extend({
parse: function(data){
return data["all-users"];
}
});
So your Collection will only consist of what the parse method returns, in this case the all-users array from your response json.
I’m trying to understand how and where to use data after a fetch using Backbone.js but I’m a little confused.
I’ll explain the situation.
I have an app that, on the startup, get some data from a server. Three different kind of data.
Let’s suppose Airplanes, Bikes, Cars.
To do that, I’ve inserted inside the three collections (Airplanes, Cars, Bikes) the url where to get these data.
I’ve overwrited the parse method, so I can modify the string that I get, order it, and put it in an object and inside localstorage. I need it to be persistent because I need to use those 3 data structure.
So with a fetch i get all those data and put them inside localstorage. Is it correct doing it that way?
Now i need to make other calls to the server, like “get the nearest car”.
In the view i need to see the color, name and model of the car, all that informations are inside the object “Cars” in localstorage.
In my view “showcars.view” I just call a non-backbone js, (not a collection, model or view) where i get all the informations i need. In this js i do:
var carmodel = new Car(); //car is the backbone model of the cars
carmodel.url = '/get/nearest/car'; //that give id of the nearest car
carmodel.fetch ({
success: function () {}
//here i search the Cars object for a car with the same id
//and get name, color, model and put them in sessionstorage
})
So after that call, in the view I can get the data I need from the sessionstorage.
Is that a bad way of doing things? If so, how i should fetch and analyze those informations? I should do all the calls and operations inside the models?
Thanks
This would be the way that you might implement what you want.
var Car = Backbone.Model.extend();
var Cars = Backbone.Collection.extend({
model: Car,
url: '.../cars'
});
var NearestCar = Backbone.Model.extend({
url: '...nearest/car'
});
var cars = new Cars();
var nearestCar = new NeaerestCar();
cars.fetch({
success: function() {
nearestCar.fetch({
success: function(model) {
var oneYouWant = cars.get(model.get('id'));
// do something with your car
// e.g.:
// var carView = new CarView({model: oneYouWant});
// $('body').append(carView.render().el);
});
});
});
});
In general, Backbone keeps everything in memory (that is, the browser memory) so there is no need to save everything to local storage, as long as your Collection object is somehow reachable from the scope you are sitting in (to keep things simple let's say this is the global window scope).
So in your case I will have something like three collections:
window.Cars
window.Airplanes
window.Bikes
Now you want the nearest. Assuming you are in a Backbone View and are responding to an event, in your place I would do something like this (just shows the meaningful code):
var GeneralView = Backbone.View.extend({
events: { "click .getNearestCar": "_getNearestCar" },
_getNearestCar: function () {
$.getJson('/get/nearest/car', function (data) {
// suppose the data.id is the id of the nearest car
var nearestCar = window.Cars.get(data.id)
// do what you plase with nearestCar...
});
}
});
var sgt1 = Backbone.Collection.extend({
model: sgt2
});
var a = new sgt1();
a.add({attr1: 'asd'});
Ok, up to now it is works but:
a.get(0) returns undefined
and
a.at(0) returns an obj
Why does get return undefined?
a.get(0) fetches by ID. It is not the same as at which fetches by index position. Since your model does not yet have an ID, get would not work.
With get() you query the collection by the models id field and not by its index like with at(). Please refer to the documentation.
I have an API that filters a set of objects based on the ID present in the URL, like so:
http://localhost:8000/api/v1/goal_update/?goal__id=12&format=json
I have a collection that does a GET request on the above URL. Here is the code for the collection:
var GoalUpdateList = Backbone.Collection.extend({
// Reference the Goal Update model
model: GoalUpdate,
// Do HTTP requests on this endpoint
url: function() {
return "http://localhost:8000/api/v1/goal_update/?goal__id=" + this.goal_id + "&format=json";
},
// Set the goal ID that the goal update list corresponds to
initialize: function(goal_id) {
this.goal_id = goal_id;
},
});
I want to pass in the ID when I create a new instance of the collection, so I created a view that has this code:
this.collection = new GoalUpdateList(this.model.get("id"));
It thinks that I am passing in model parameters, though. I am trying to pass in information that tells the collection what URL to use. So it runs the ID through a validate function and messes up the rest of the backbone code.
Backbone's collections expect model data as the first parameter, as you've already noted. But you can specify a second parameter as an object literal, like other Backbone objects. Just pass null or undefined as the first parameter, and then in your collection initialize method, get the options as the second parameter.
GoalUpdateList = Backbone.Collection.extend({
initialize: function(data, options){
this.goal_id = options.goal_id;
}
});
new GoalUpdateList(null, model.get("goal_id"));