When will custom datasource complete loading data?

Question

I'm trying create my own datasource. I'm following the sample code.

Basically, I dont know, how I will know the datasource has completed fetching data. Could any provide me a hint/sample?

Answer 1

There are multiple controls to display progress...
http://msdn.microsoft.com/en-us/library/windows/apps/hh465451.aspx#progress_controls

Please check the guidelines for which progress control to be used in which scnario

http://msdn.microsoft.com/en-us/library/windows/apps/hh465469.aspx

having said that, let's assume you want to use progress ring (indeterminate progress ring )......
put a div tag in default.html file

<div id="myprogressdiv">
        <progress id="myprogress" class="win-ring"></progress>
    </div>

And then, in the method, which calls the service/gets data from datasource; put the below line as the first line:

$("#myprogressdiv").show();

And then, at then end of that method, after the call for the data has been made, put the below line:

$("#myprogressdiv").hide();

Hope this helps

---

Arindam Basu

Answer 2

My question not about showing progress control. I want to know when, the custom data source will complete loading data, so that I have hide my progress control. 

Answer 3

I would also like  to know, if the custom data handler will return any promise.  Then showing/hiding progress control is not a problem.

Answer 4

In the sample u can do the following:

1. Add a completionCallback into the constructor of bingImageSearchDataAdapter

// Definition of the data adapter
var bingImageSearchDataAdapter = WinJS.Class.define(
    function (devkey, query, completionCallback) {

        this._completionCallback = completionCallback;

        // Constructor
        this._minPageSize = 50;
        this._maxPageSize = 50;
        this._maxCount = 1000;
        this._devkey = devkey;
        this._query = query;
    },

2. call the completionCallback in the getCount() function and call it just before count is returned:

if (that._completionCallback)
    that._completionCallback()

return count;

3. Next, in scenario1.js, adjust the new'ing up of the bingImageSearchDataSource to this:

//Create the bing itemDataSource
var myDataSrc = new bingImageSearchDataSource.datasource(devkey, searchTerm, function completionCallback()
{
    // hide the ring here
});

To sum it up, i've added a callback to the bingImageSearchDataAdapter and call it once the data is loaded. Then in the new'ing up of the datasource i've provided the actual implementation of the callback in where u can do your thing.

Good luck!