The widget example at http://docs.angularjs.org/guide/dev_guide.forms section "Implementing custom form control (using ngModel)" is out of date or just wrong.

The example SEEMS to work, but in reality it doesn't really do data binding correctly. For example of the underlying "content" model changes, the widget will not update (try it).

The issues are:

• the render function is actually called $render now
• the $render function does not take a parameter value, instead it should read the value from $viewValue

This code works better: http://jsfiddle.net/Jju2m/1/