buffering.js

Jump To … +

advanced_filters.js advanced_views.js basic_pourover_ing.js buffering.js

buffering.js
¶

#Buffering example This example will show how to use BufferedCollections and BufferedViewsto lazily load full-text data, rather than mandating that every item in the collection has it’s entire set of attributes from the beginning. Of course, you cannot filter on buffered attributes. BufferedCollections and BufferedViews simply provide a mechanism for rending Views that depend on buffered data.
¶

BufferedCollections are just like Collections, except for a few new methods and a few modifications.
- BufferedCollection maintain a dictionary between guids and buffered values, this dictionary is used to provide the full attributes for some item
- get and getBy are slightly altered so that they merge in the buffered attributes from the collection. However, these functions are used the same way as the vanilla Collection counterparts.
- When creating buffered collections you must supply a ‘getBufferUrl’ function that can transform an array of guids into a url that will return full data for that set of guids
- bufferGuids takes a set of guids and returns a promise. This promise will return after the full attributes are available for the specified guids

Say you had a server at example.com/data?guids=[guids]

var monsters = [{name: "sphinx", mythology: "greek", eyes: 2, sex: "f", hobbies: ["riddles","sitting","being a wonder"],guid:1},
                {name: "hydra", mythology: "greek", eyes: 18, sex: "m", hobbies: ["coiling","terrorizing","growing"],guid:2},
                {name: "huldra", mythology: "norse", eyes: 2, sex: "f", hobbies: ["luring","terrorizing"],guid:3},
                {name: "cyclops", mythology: "greek", eyes: 1, sex: "m", hobbies: ["staring","terrorizing"],guid:4},
                {name: "fenrir", mythology: "norse", eyes: 2, sex: "m", hobbies: ["growing","god-killing"],guid:5},
                {name: "medusa",  mythology: "greek", eyes: 2, sex: "f", hobbies: ["coiling","staring"],guid:6}];

var MyBufferedCollection = PourOver.BufferedCollection.extend({
    getBufferUrl: function(guids){
        var query = encodeURIComponent(guids.join(","));
        return "http://example.com/data?guids="+query;
    }
});
var collection = new MyBufferedCollection(monsters);

¶

BufferedViews can only be defined on BufferedCollections. Buffered views provide paging and rendering functions that buffer in the relevant items, those which are returned from getCurrentItems(), (using the collection’s bufferGuids function) and then delegate back to the default render function of the view
```
var MyBufferedView = PourOver.BufferedView.extend({
    render: function(){
       var items = this.getCurrentItems();
       console.log(items);
    }
});
var my_buffered_view = new MyBufferedView("buffered_view",collection);
```
¶

We call bufferRender instead of render, so that the collection buffers the data before relinquishing control back to the vanilla render.
```
my_buffered_view.bufferRender();
```
¶

Of course, here nothing will happen because the example.com URL will never resolve