Last Updated: 24 Nov 2014 16:45 by ADMIN
Telerik Admin
Created on: 20 Aug 2013 20:33
Category: Data Source
Type: Feature Request
DataSource's "read", "fetch", and "sync" methods should return a deferred
There has been many scenarios where I've needed to know when a DataSource finishes a "read" or "sync" operation.

I know there's the global "sync" event that I can bind to, but a lot of the time I only care about the result of one specific sync call. I can use the "one" method to only listen to it once, but this complicates things when I also care about errors. Since I need to register callbacks for both the "sync" and "error" events, and then unregister either one or the other, depending on which event fired.

It's even harder hooking into a "read" event because the DataSource doesn't expose one. I know I can hook into the "change" event of the DataSource, but I still have to guess whether the change event was fired because of read, or because of some other change.

If these methods returned a deferred it would be a lot easier to handle the circumstances where an app needs to do additional things after a "read" or "sync" is completed.
Telerik Admin
Posted on: 24 Nov 2014 16:45
There's no specific example for this feature, however you can request one from our support team using our forums or support system on
Posted on: 24 Nov 2014 09:00
where can we see the example ?
Telerik Admin
Posted on: 21 Nov 2014 14:25
Implemented with Q3 2014
Posted on: 11 Nov 2014 17:03
A definitve and urgent YES!
Telerik Admin
Posted on: 29 Sep 2014 16:25
I'll pass your additional feedback to our devteam, Remco. For now we'll be targeting only the read, fetch and sync methods.
Imported User
Posted on: 29 Sep 2014 16:00
great news. For completeness and consistency, as well as the "read", "fetch" and "sync" methods returning a promise, would you also have the "query", "aggregate". "filter", "group", "page", "pageSize" and "sort" methods return a promise? 

Obviously with serverAggregates, serverFiltering, serverGrouping, serverPaging and serverSorting set to false these promises would be immediately resolved (and assuming you'll be using JQuery promises they'll also be sequential, whereas when Promises/A+ compliant they should be asynchronous), and with serverAggregates, serverFiltering, serverGrouping, serverPaging and serverSorting set to true these promises would initially be pending (asynchronous).
Imported User
Posted on: 19 Sep 2014 15:15
Is there any update on the state of this feautre? It would make many things easier.
An information would be great.
Imported User
Posted on: 21 Apr 2014 14:07
This is a very important enhancement at our site. Please implement ASAP.
Posted on: 17 Apr 2014 13:52
The absence of this feature , kill many times of our company. Especially when you are working with MVVM and there may be error or success and you should use `once` and `unbind`. Which in our case `unbind` did not unbind the listener attached to error or success event. Just for god add this capability in Q2 2014. Our company are tempting to leave kendo away.
Posted on: 24 Feb 2014 00:19
This has been under review for some time, is this happening?
Posted on: 17 Nov 2013 20:13
A thousand times yes on this
Posted on: 31 Oct 2013 10:15
Agreed 100%. This is one of the few things that annoy me about Kendo. Please implement.