Dependent methods that depend on other dependent methods (with jsfiddle)

[Paul]

I am looking to have a validation message only be populated when needed. So I have an observable object with 3 fields: Value, IsValid, and Message. IsValid is dependent on Value, and Message is dependent on IsValid.

http://jsfiddle.net/GExfL/

var viewModel = kendo.observable({

    OrderNumber: {

        Value: '',

        IsValid: function(){

            return (this.get('Value').length >= 8);

        },

        Message: function(){

            if(this.get('IsValid')){

                return '';

            }

            else{

                return 'Text length must be at least 8 characters.';

            }

        }

    }

});

It doesn't appear that this is allowed, but is there an easy way to design the VM to get something similar?

The closest I've come up with is a utility method that is shared by both IsValid and Message (http://jsfiddle.net/GExfL/1/), but it seems a little verbose.

[Martin]

Actually quite a simple solution: http://jsfiddle.net/GExfL/2/

var viewModel = kendo.observable({

    OrderNumber: {

        Value: '',

        IsValid: function(){

            return (this.get('Value').length >= 8);

        },

        Message: function(){

            if(this.IsValid()){

                return '';

            }

            else{

                return 'Text length must be at least 8 characters.';

            }

        }

    }

});

I believe that you only need to use this.get on raw values, not calculated values.