Why when I click on the update button error TypeError: r is undefined happen?

Question

The error in firefox browser as follows: TypeError: r is undefined

This is the chrome browser: Uncaught TypeError: Cannot read property 'data' of undefined

I also did a video for a better understanding.

The error occurs when I changed the values ​​in a field

jsfiddle code

youtube video

button code update

      save: function (e) {
            var that = this;
            $.ajax({

                url: '/api/apdevice',
                type: e.model.id == null ? 'POST' : 'PUT',
                contentType: 'application/json',
                data: JSON.stringify(e.model),
                success: function (data) {
                    alert('yes');
                    that.refresh();
                },

                error: function (data) {
                    alert('no');
                    that.cancelRow();
                }

            });
        }

Solution

The reason for this is because your datasource's update method is being called. It has not been set which gives you the TypeError.

You can do one of two things.

1. Set the update method of your datasource to contain the logic contained in your save function. You'll need to set update as a function in order to be able to control the method dynamically (POST/PUT). You should remove the ajax code from the save event at this point.
2. Set the update method to a dummy function and handle it as part of the save event instead.

Here's an example of approach #2.

var dataSource = new kendo.data.DataSource({
  ..
  update: function(e) { return true; }
  ..
});

Keep the save event function as is.

Note that I'm getting an Uncaught SyntaxError: Unexpected number error. I believe this is originating from the LastClientsCount property.

Fiddle: http://jsfiddle.net/mSRUe/23/