Cannot generate URL correctly

[chengyin]

I am not sure how this is supposed to work, but with the example code showed in the backbone.js document:

var Book = Backbone.Model.extend({urlRoot : '/books'});
var solaris = new Book({id: "1083-lem-solaris"});
alert(solaris.url());

We get '/books' with backbone-tastypie. This is due to the overwritten on idAttribute and url.

[chengyin]

So the resource_uri is expected to be used as the id and it should be the full URI of the model. I do not understand this design, could you explain? Thank you.

[PaulUithol]

Well, that the url is just /books for a new object is entirely correct, isn't it? If you save it, you should do a POST request to /books, and Tastypie will return you an object containing a resource_uri.

[chengyin]

What if it is a exist object I want to get? Say, the id is from the URL.

[PaulUithol]

If it's an existing object, wouldn't that mean you've fetched it from the server, or as a relation from another model? In that case, you'd have it's resource_uri. I've never encountered a situation where I'd have an id, but not the resource_uri?

[nathanborror]

I do a lot of fetching with just ID's and this works in vanilla Backbone. I ended up removing your url and idAttribute overrides and everything worked just fine.

[chachra]

I concur with Nathan. just using id is very much helpful in many cases.

[PaulUithol]

Could you give me an actual example maybe? Because I think I don't entirely understand the complete use case yet.

My understanding at the moment is that sometimes you have models without a resource_uri (if you did, there wouldn't be a problem fetching it, right?). If that's the case, it's possible you do already have an id in some way that can be used with the urlRoot to construct a complete url from.

If that's correct, that would be pretty easy to add.

[chachra]

Paul,

See the backbone documentation. It lets you give a new object an id (meaning u have it in the backend, but in the frontend you are giving an id to tell it how to construct url and fetch it) etc.

http://documentcloud.github.com/backbone/#Model-urlRoot

[PaulUithol]

Thanks, but I know Backbone quite well ;). I'm just trying to clarify how the behavior for url should be in relation to the model's id attribute and Tastypie's resource_uri. So if the following sounds okay, this should be pretty trivial to fix:

• Normally (when requesting data from the server), the current behavior (constructing a url from the resource_uri) is fine;
• however, there are cases where you do have an actual, existing (hopefully ;) id attribute but the model doesn't contain a resource_uri;
• in these cases, it'd be nice if the url function could just use the id attribute (so, use model.get('id') as opposed to model.id) and attach it to the urlRoot.

[chachra]

thats correct. Thanks Paul!

[nathanborror]

This doesn't appear to fix the problem. When .url() is called now it just returns the id of the model instead of the full url. What if the override was something like:

Backbone.Model.prototype.url = function() {
  // If there's no idAttribute, use the 'urlRoot'. Fallback to try to have the collection construct a url.
  // Explicitly add the 'id' attribute if the model has one.
  if (!this.id) {
    url = this.urlRoot;
    url = url || this.collection && (_.isFunction(this.collection.url)? this.collection.url(): this.collection.url);

    if (url && this.has('id')) {
      url = addSlash(url) + this.get('id');
    }
    url = url && addSlash(url);
    return url || null;
  }
  else {
    var base = getUrl(this.collection) || this.urlRoot || urlError();
    if (this.isNew()) return base;
    return base + (base.charAt(base.length - 1) == '/' ? '' : '/') + encodeURIComponent(this.id);
  }
};

I just hacked this together, it could probably be optimized :/

[PaulUithol]

I don't see how it wouldn't work, as long as you a) set the urlRoot to the proper value, and b) leave idAttribute pointing to resource_uri (as it should be for tastypie?).

(btw, both getUrl and urlError are functions in Backbone's local scope, as far as I know)

[nathanborror]

Have you tested it yourself?

[PaulUithol]

Well, yes? See tests.js:

    test("Model url", function() {
        var person = new Person();
        equal( person.url(), null );

        // If the model doesn't have an 'urlRoot' and no value for it's 'idAttribute', the collection's
        // 'urlRoot' is be used as a fallback ( a POST there creates a resource).
        var coll = new Backbone.Collection();
        coll.urlRoot = '/persons';
        person.collection = coll;
        equal( person.url(), '/persons/' );

        // If present, the model's urlRoot is used as a fallback.
        person.urlRoot = '/person';
        equal( person.url(), '/person/' );

        // The value of the explicit 'id' attribute is added to the 'urlRoot' when available
        person.set( 'id', 2 );
        equal( person.url(), '/person/2/' );

        // If the idAttribute is set, it's used as the uri verbatim.
        person.set( { resource_uri: '/person/1/' } );
        equal( person.url(), '/person/1/' );
    });

Could you check if these tests pass for you? If they do and you have a scenario that does fail, please share the testcase.