var items=[{"endsAt": "2013-05-26T07:00:00Z","id": 1,"name": "Niuniu1"},
{"endsAt": "2013-05-26T07:00:00Z","id": 2,"name": "Niuniu2"}]
ItemModel=Backbone.Model.extend({});
ItemCollection=Backbone.Collection.extend({
model:ItemModel,
url: '...',
parse: function(response) {
return response.items;
}
})
If I have a series of data like items, when I build model, for each model, it's endAt will be "2013-05-26T07:00:00Z". Where can I modify the model or data process so it will actually be "2013-05-26"?
I could do a foreach loop inside collection to process the date, but I'm wondering if there is a better pracitce like to do a parse inside the model?
Thanks!
The practice I use is the one you said you've thought about - implementing a custom parse on the model. As the documentation states, it will be called for you after a sync. See here: http://backbonejs.org/#Model-parse
ItemModel = Backbone.Model.extend({
parse: function(response,options) {
//perform your work on 'response',
// return the attributes this model should have.
};
})
As far as I know, you have 2 options here
Implement a custom parse method inside your model
Implement the initialize method inside your model
Both of them don't have any problems, I did 2 ways in several projects, and they work well
Related
I have a dictionary of type {name: value}
A = {
name: x,
name: y,
name: z
}
I want to fetch a collection (consisting of models having one of their attribute as 'name'), but to be optimal I want to fetch such that the value of the attribute 'name' exists in my dictionary.
Is there a way to do specific filtering like that?
If you're doing the filtering client-side, overriding the filter method is really NOT the way to go.
Now you no longer have it available, should you need it later. Also, modifying the collection itself from within the filter method is an undesirable sideeffect.
Instead you should be using the parse method, which will automatically be called when fetching the collection.
Now as I understand it, you want to limit the fetched set to models with names matching the keys in your dictionary.
If so, I would do the following:
parse: function(response, options) {
// Do we want to filter the response?
if (options.filterNames) {
// Filter
response = _.filter(response, function(obj) {
// Check if this model name is one of the allowed names
return _.contains(options.filterNames, obj.name);
});
}
// Backbone will use the return value to create the collection
return response;
}
And then call fetch using
someCollection.fetch({filterNames: _.keys(someDictionary)});
If you're certain, you will always be filtering the collection on fetch, you can omit passing the option and just use the dictionary within parse.
Alternatively you could create a fetchFiltered() method on the collection, which would then invoke the line above.
After investigations and trials, here are the two ways this can be resolved:
1. Client side filtering after fetching the collection from the server. This is a less optimal method, especially when the collection is huge. In situations when you really want 5 models out of a 1000 model collection, it can be an overkill. But if the server side has no logic of accepting and using the filtering client side filtering should look something like:
Overload the collection filter code something like:
var filter = {
filter: function() {
var results = _.filter(this.models, function(model) {
// Perform the check on this model, like compare it to your local dict
if (checkPassed) {
return true;
}
return false;
});
results = _.map(results, function(model) {
return model.toJSON();
});
// Reset the existing collection to filtered models
this.reset(results) ;
};
var ExtendedCollection = OriginalCollection.extend(filter);
Pass a filter option in the fetch ajax call to the server, and the server should understand the filter and return the collection based off that.
I have a backbone model which has Backbone Collections in it. When I save the model and if it is success then my model object is properly structured as it was. But when error occurs (say validation error), in error callback the model object is modified (Collections inside model object are converted into Array). As a result all my functions defined for that Collections are now "undefined" and gives me error.
save : function() {
this.model.save(_.extend(originalModel.toJSON() || {}, this.model
.toJSON()), {
success : this.onSaveSuccess,
error: this.onSaveError,
include : []
});
},
onSaveSuccess : function(model) {
//Here the model is properly structured
},
onSaveError : function(model, response) {
// Here the model is modified, all collections are now array
//I have to explicitly call my parse method to re structure it.
model = model.parse(model.attributes);
}
I would like to know why is this happening. Am I doing something wrong here ?
For the sake of this example, let's assume the attribute of the model that holds the collection is called "people". It isn't clearly documented, but model.save(attributes) actually behaves like:
model.set(attributes);
model.save();
Here's the relevant annotated source of save(...). What your code is doing is first setting the "people" attribute to the array of people, then attempting to save it. When the save fails, your model has the array, not the collection, as the value of "people".
I suspect your end point is returning the full representation of the model on success, and your model is correctly parsing that representation & re-building the Collection at that point. But your error handler won't do that automatically.
As an aside, in my experience Models that contain Collections are hard to manage & reason about. I've had better luck having a Model that contains an array of data, and then having a method on that Model to build a Collection on the fly. Something like:
var MyModel = Backbone.Model.extend({
// ...
getPeople: function() {
// See if we've previously built this collection
if (!this._peopleCollection) {
var people = this.get('people');
this._peopleCollection = new Backbone.Collection(people);
}
return this._peopleCollection;
}
});
This removes the Collection concept from the server communication (where it's pretty unnecessary), while also providing a smarter data layer of your application (smart Models are a good thing).
The solution for this is passing wait:true in options. This will not modify until and unless server returns a valid response.
save : function() {
this.model.save(_.extend(originalModel.toJSON() || {}, this.model
.toJSON()), {
success : this.onSaveSuccess,
error: this.onSaveError,
**wait:true**
include : []
});
},
Got a server returning a JSON object like so:
{
'key1':'value'
'key2':{
'key2_0':'value'
}
}
And a collection:
var Collection = Backbone.Collection.extend({
url:api.url//which returns the object above
});
var collection = new Collection();
collection.fetch({
success:function(data){
//do something
}
});
Now i need to use certain properties of the collection throughout my application, but say i need key1, i always have to do collection.at(0).get('key1');//returns 'value', because the data returned is stored within the collection, in a new Array at key 0.
Question:
How to directly... collection.get('key1')//now returns undefined... because it is.
I know i could expose an object to the global scope in the collection success function some_other_var = data.toJSON()[0] and access the some_other_var properties directly, but that's not what i'm looking for;
In order to use the get() function from a Backbone.Collection you need to know the model id or cid wanted.
For instance, lets say your data coming from the server is like follow:
[{
id: '123',
name: 'Alex'
}, {
id: '456',
name: 'Jhon'
}]
In that case you can do this:
this.collection.get('123').get('name') // Return "Alex"
Keep in mind that collection is just a set of model, so behind the scenes by doing collection.get() you are getting a model
Tip: If you don't have any kind of id in your server data, there is always the option of using underscore methods:
find
filter
some
contains
etc
It seems like you're trying to ascribe attributes to a collection, but a collection is merely a set of models. Having additional data that is constant throughout the collection suggests that it should be wrapped inside another Model, which is demonstrated here: Persisting & loading metadata in a backbone.js collection
I have this code in my Backbone application:
app.Collections.quotes = new app.Collections.Quotes();
app.Collections.quotes.fetch();
And I can see an array of Objects returned in the network tab but when I expand out the Collection, the Models array inside is 0. Do they get instantiated as Models when fetch() is ran on a new Collection?
This is my Collection:
app.Collections.Quotes = Backbone.Collection.extend({
model: app.Models.Quote,
url: function() {
return app.Settings.apiUrl() + '/quotes';
}
});
EDIT:
app.Collections.quotes.fetch({
success: function(){
app.Utils.ViewManager.swap('section', new app.Views.section({section: 'quotes'}));
}
});
And in my Model:
idAttribute: 'Number',
This was the fix! Thanks for help. Dan kinda pointed me in the right direction amongst the comments...
Calling fetch() on a Collection attempts to populate the JSON response into Models: Collection#fetch.
Is your server definitely returning a valid JSON array of objects?
Do you have any validation on your Quote Model? I'm pretty sure Backbone validates each models before populating the collection, only populating with the models which pass. So if it exists, check that your Model#validate method is working correctly.
You shouldn't need an ID (although it's obviously required if you want to edit them).
I know this error has come up a few times, but I'm still not sure how to make this work appropriately..
My magic begins here :
var list_edit_member_view = new app.views.ListMemberEdit({
el: $("#enterprise_member_list_edit_container"),
list_ids: list_ids
});
list_edit_member_view.render();
And this loads this View (ListMemberEdit.js) which has this in the render() :
this.list_edit_member_view = new app.views.CollectionView({
el: $("#enterprise_member_list_edit_container"),
collection: app.peers,
list_item: app.views.ListMemberEditSelection,
list_item_options: {list_ids: this.options.list_ids}
});
Which loads a CollectionView view that renders its list_item_options as model views.. It is within this file (ListMemberEditSelection.js), that when I perform this.destroy, it will return :
Uncaught Error: A "url" property or function must be specified
So this makes me think that the Model or the Model URL is not being defined.. I'm just not sure where to put this since it works very similar to my other partials that are doing roughly the same thing..
Any thoughts? My apologies for the vagueness. Let me know if there's anything else you would like to look at!
I'm curious if its possible to see where this URL attribute would be written within the Object Model or Collection itself.
This is because destroy() function will call Backbone.sync to update the server too, not only your models in the frontend. http://backbonejs.org/#Model-destroy
So, if you're using REST to sync your data, you'll need to set a url property in your model so Backbone know where to send request:
Backbone.Model.extend({
url: "http://myapi.com/"
})
To allow more flexibility, you can also set a urlRoot: http://backbonejs.org/#Model-urlRoot
I had a similar problem, I removed the "id":"" from my models default values and the problem was solved.
I did receive similar error
Try this: I am just making an assumption what your model might look like
window.MyModel = Backbone.Model.extend({
url: function(){
return this.instanceUrl;
},
initialize: function(props){
this.instanceUrl = props.url;
}
}
Please look at this question that I had posted myself for more details: https://stackoverflow.com/a/11700275/405117
I am providing this reference as the answers here helped me better understand
Hope this helps!