Why isn't my ember.js route model being called

问题:

I just started learning Ember.js (bought the PeepCode screencast), and am learning quite smoothly from it, but ran into a problem when trying to write my first Ember app.

Here's the (nested) route mapping:

App.Router.map(function () {
    this.resource('bases', { path: '/' }, function () {
        this.resource('base', { path: ':base_id' }, function () {
            this.resource('places', function () {
                this.resource('place', { path: ':place_id' });
            });
        });
    });
});

This allows urls like this: domain.com/#/yokota-ab-japan/places/4c806eabd92ea093ea2e3872

yokota-ab-japan is the id of a base (an Air Force base in Japan) 4c806eabd92ea093ea2e3872 is the id of a venue on Foursquare

When the places route is hit, I setup the data with a call to the foursquare api, iterate over the JSON to create an array of App.Place objects, and return that array.

App.PlacesRoute = Ember.Route.extend({
    model: function () {
        var placesData = Ember.A();
        $.getJSON('https://api.foursquare.com/v2/venues/search?ll=35.744771,139.349456&query=ramen&client_id=nnn&client_secret=nnn&v=20120101',
            function (data) {
                $.each(data.response.venues, function (i, venues) {
                    placesData.addObject(App.Place.create({ id: venues.id, name: venues.name, lat: venues.location.lat, lng: venues.location.lng }));
                });
            });

        return placesData;
    }
});

That seems to work well. I display the placesData array using this template:

<script type="text/x-handlebars" data-template-name="places">
    <div>
        {{#each place in controller}}
            {{#linkTo 'place' place}}
                {{place.name}}
            {{/linkTo}}
        {{/each}}
    </div>

    {{outlet}}
</script>

The linkTo links to the individual place, where I want to show more details about a place. Here's the route I setup to pull data about the single place, populate a single App.Place object, and return it:

App.PlaceRoute = Ember.Route.extend({
    model: function (params) {
        console.log('place route called');

        var place;
        $.getJSON('https://api.foursquare.com/v2/venues/' + params.place_id + '?client_id=nnn&client_secret=nnn',
            function (data) {
                var v = data.response.venue;
                place = App.Place.create({ id: v.id, name: v.name, lat: v.location.lat, lng: v.location.lng });
            });

        return place;
    }
});

My problem is, PlaceRoute doesn't get called when the user clicks a link to it, but it does get called when the page is refreshed on this route.

According to the PeepCode Ember.js screencast (at ~12:25 into the video) it states that "controllers rarely ever make calls to data, route objects handle that", so I think I'm correct in putting my ajax calls in the routes (I've seen so many differing tutorials online, but since Peepcode consulted with the Ember.js creators, I went with it as my primary learning source).

If this isn't correct, or could be done better, please let me know.

回答1:

Ember Documentation on the model hook:

"A hook you can implement to convert the URL into the model for this route."

This explains why the model hook is just called on page refresh. But this confuses a lot of people :-). So, this is not the right hook in this case. I think you should use the setupController hook for this case. Try this:

App.PlaceRoute = Ember.Route.extend({
    setupController: function (controller, model) {
        console.log('place route called');

        var place;
        $.getJSON('https://api.foursquare.com/v2/venues/' + model.get('place_id') + '?client_id=nnn&client_secret=nnn',
            function (data) {
                var v = data.response.venue;
                place = App.Place.create({ id: v.id, name: v.name, lat: v.location.lat, lng: v.location.lng });
            });

        controller.set("model", place);
    }
});

Additional 2 cents from myself: Why is the model hook just executed, when the app is entered via URL/direct browser navigation?

Ember has the assumption, that you do not necessarily make a call to the model hook, if you use {{linkTo}}. In your places template you use {{#linkTo 'place' place}} {{place.name}} {{/linkTo}}. You are passing a place object to your route. Ember assumes that this is the same object, that you would get when executing your model hook. So from Embers View there is no need to call the model hook. So if you want to perform retrieval logic even when you use linkTo, use the setupController hook.

回答2:

FYI:

You could use the model hook for this kind of thing, just pass the id instead of the object:

{{#link-to 'place' place.id}}
    {{place.name}}
{{/link-to}}

As Ember no longer knows which object is related to given id, Ember is forced to reload the data (so Ember calls the model hook).

回答3:

Based on mavilein's answer, but shorter and suitable for Ember CLI with Ember Data...

import Ember from 'ember';

export default Ember.Route.extend({
  setupController: function( controller, model ) {
    controller.set( "model", this.store.fetch( 'place', model.id ) );
  },
});

Also note that the fetch method is only available from Ember Data 1.0.0-beta.12.

http://emberjs.com/api/data/classes/DS.Store.html#method_fetch