Knockout JS Ajax call not populating observable ar

问题:

The below example shows an observable array being populated from with Json, which then allows you to filter the results into 2 lists based on 'type'.

This all works fine until I try and load exactly the same Json from a ajax call!

The strange thing is if i put an alert in the script it then works fine...

http://jsfiddle.net/spdKE/3/

<h2>Brand</h2>
<ul id="list-dimensions" data-bind="foreach: filteredDimensions('BRAND')">
    <li>
        <div class="item">ID</div> <span data-bind="text: $data.id"</span>
    </li>
</ul>
<h2>Area</h2>
<ul id="list-dimensions" data-bind="foreach: filteredDimensions('AREA')">
    <li>
        <div class="item">ID</div> <span data-bind="text: $data.id"</span>
    </li>
</ul>​

function ProductDimensionsViewModel () {
        var self = this;
        self.dimensions = ko.observableArray();

        var baseUri = 'api/product_dimensions.php';


        /*$.getJSON(baseUri, function(data){
            success: self.dimensions = data;
        });*/

        $.ajax({
            type: 'GET',
            url: baseUri,
            data: {},
            context: this,
            success: function(data) {
                self.dimensions = data
            },
            dataType: 'json'
        });


        self.filteredDimensions = function(type) {
        return $.map(self.dimensions, function(dimension) {
                if (dimension.type == type) {
                    return dimension;
                }
            });
        }

    }





        ko.applyBindings(new ProductDimensionsViewModel());

回答1:

You are replacing the variable, not updating it:

...
success: function(data) {
  self.dimensions = data
},
...

Observables are updated this way:

...
success: function(data) {
  self.dimensions(data)
},
...

I wouldn't use filteredDimensions('AREA') because this gets call as soon as your page is rendered. Use observables, store in a variable currentFilter the value and then through a template load the proper view. Also, if you only have two filters, a better approach is just to have two methods: filterByArea and filterByBrand.

EDIT: Added example: http://jsfiddle.net/jjperezaguinaga/spdKE/4/